Wild Dog Adventure Riding

General => About South Africa... => Topic started by: Heimer on September 14, 2011, 10:46:19 pm

Title: Where is the geographic centre of South Africa?
Post by: Heimer on September 14, 2011, 10:46:19 pm
I see on the web, Kimberley lies 58km from the geographic centre of South Africa.

Others claim it is Bloemfontein

Also - Phillipolis says they are near it

Does anybody know exactly where the spot is? Someone must have already made a rock pile...

Post picture here, please as well as the co-oprdinates. That is a cool stop-over for a leg stretch if it is accessible...

Additionally, it would be great to know the geographice centres of each of the provinces, so one can tick these off during trips.

Who can help?
Title: Re: Where is the geographic centre of South Africa?
Post by: Lourens ツ on September 14, 2011, 11:16:01 pm
How would one find the geographic centre of South Africa? The crossing point between the most Northern/Southern & Eastern/Western points in SA?

That would be S27.89008 E25.62496
Title: Re: Where is the geographic centre of South Africa?
Post by: KiLRoy on September 14, 2011, 11:23:32 pm
or when having the same square kms in each quarter?
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 15, 2011, 07:17:13 am
Some complex maths required. Its an uneven land mass & drawing just two lines looks wrong?
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 08:49:47 am
Some complex maths required. Its an uneven land mass & drawing just two lines looks wrong?
Not if you calculate from the furthest points, that is the most logical. :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 15, 2011, 08:52:52 am
Some complex maths required. Its an uneven land mass & drawing just two lines looks wrong?
Not if you calculate from the furthest points, that is the most logical. :mwink:
Then lines must go from other land/border extremeties. Like from EL & Katlegadi etc etc
Title: Re: Where is the geographic centre of South Africa?
Post by: jano on September 15, 2011, 08:55:35 am
It should be the COG of South Africa ;-) this would depend on whether most of SA is sitting or standing at the time ...

I would draw a horizontal line, such that the landmass of SA above and below the line are equal. Same for a vertical line, landmass on left and right equal. Where they intersect is the centre.
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 08:55:51 am
Some complex maths required. Its an uneven land mass & drawing just two lines looks wrong?
Not if you calculate from the furthest points, that is the most logical. :mwink:
Then lines must go from other land/border extremeties. Like from EL & Katlegadi etc etc
Look again at Lourens's points, they are the most Northern, Southern, eastern and western. Or you could do the excercise from each km along our border. I like the simple logical approach. :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Kobus on September 15, 2011, 10:47:08 am
I would like to know the result of this method.

Who has some spare time?  >:D

"You find it, if you transfer the shape of a country on cardboard, cut it out and look for the centre of gravity of this slice. You can also simulate this process by a computer."
Title: Re: Where is the geographic centre of South Africa?
Post by: tok-tokkie on September 15, 2011, 10:54:58 am
Two ways I would do it:

1. Most north & south points (west of Messina & Agulhas) add the latitude then divide by 2 to give the mean latitude.   Do same for east/west.

2. Center of Gravity method, which I prefer.  Get a map of SA & stick it to thick cardboard.  Cut around the edge of SA with an Exacto knife & cut out Lesotho so just the SA landmass remains.  Stick a pin through near Messina & pin to a vertical board, must be free to swing.  Hang a piece of cotton with small weight from pin.  Draw line where cotton thread lies.  Repeat near Richards Bay & Alexander Bay.  3 lines should cross at a point = CofG of the cardboard.
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 10:57:02 am
Two ways I would do it:

1. Most north & south points (west of Messina & Agulhas) add the latitude then divide by 2 to give the mean latitude.   Do same for east/west.

2. Center of Gravity method, which I prefer.  Get a map of SA & stick it to thick cardboard.  Cut around the edge of SA with an Exacto knife & cut out Lesotho so just the SA landmass remains.  Stick a pin through near Messina & pin to a vertical board, must be free to swing.  Hang a piece of cotton with small weight from pin.  Draw line where cotton thread lies.  Repeat near Richards Bay & Alexander Bay.  3 lines should cross at a point = CofG of the cardboard.
:imaposer:
I favour option 1... off to googlemaps for a while... :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 15, 2011, 10:59:29 am
Two ways I would do it:

1. Most north & south points (west of Messina & Agulhas) add the latitude then divide by 2 to give the mean latitude.   Do same for east/west.

2. Center of Gravity method, which I prefer.  Get a map of SA & stick it to thick cardboard.  Cut around the edge of SA with an Exacto knife & cut out Lesotho so just the SA landmass remains.  Stick a pin through near Messina & pin to a vertical board, must be free to swing.  Hang a piece of cotton with small weight from pin.  Draw line where cotton thread lies.  Repeat near Richards Bay & Alexander Bay.  3 lines should cross at a point = CofG of the cardboard.
C'mon TT...off you go then!

Dibs on organising the first "Bash" there... >:D
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on September 15, 2011, 11:06:39 am
There must be an accepted method. All the US states have geocaches or stone piles at their geographic centres.

That means someone somewhere must have calculated it already.

I think.....
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 11:11:35 am
I see on the web, Kimberley lies 58km from the geographic centre of South Africa.

Others claim it is Bloemfontein

Also - Phillipolis says they are near it

Does anybody know exactly where the spot is? Someone must have already made a rock pile...

Post picture here, please as well as the co-oprdinates. That is a cool stop-over for a leg stretch if it is accessible...

Additionally, it would be great to know the geographice centres of each of the provinces, so one can tick these off during trips.

Who can help?
Kimberley it is!
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 11:12:49 am
There must be an accepted method. All the US states have geocaches or stone piles at their geographic centres.

That means someone somewhere must have calculated it already.

I think.....
Can't find any Google reference... yet
But I did draw some lines on a map... :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: DeepBass9 on September 15, 2011, 11:23:01 am
So kimberley is the dead centre?  :laughing4:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 11:25:42 am
So kimberley is the dead centre?  :laughing4:
Not quite, it seems to be just north of Kimberley, very close to the Vaal River...
Title: Re: Where is the geographic centre of South Africa?
Post by: buzzlightyear on September 15, 2011, 11:36:31 am
You mean we can't have the bash in the big hole  ;D

I still think Rob rigged this to be close to him  ;D
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 11:44:45 am
I think I found it! :deal:
Title: Re: Where is the geographic centre of South Africa?
Post by: Pote on September 15, 2011, 11:56:07 am
I think I found it! :deal:
ok so place it in planning a ride section please
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 12:02:45 pm
I think I found it! :deal:
ok so place it in planning a ride section please
Good idea... seems like there is no marker for this in SA... :-[
Unlike many other places;
http://www.waymarking.com/cat/details.aspx?f=1&guid=979fa1c8-4426-4742-90ce-d68018cfd658&wo=True&wst=6&sg=2e2f5373-207c-4f10-a4ed-40d616cbd2f2&st=2

This may be fun to plot the exact point and go and erect a marker... with a Paw! :deal: :mwink:

The pic is a googlemap snap of more or less where it should be.
Title: Re: Where is the geographic centre of South Africa?
Post by: Karel Kat on September 15, 2011, 12:06:48 pm
Jan Kempdorp, I've heard
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 15, 2011, 12:14:32 pm
How about:

Cut out a map of SA on a large card (perimeter). Balance the cut-out on a pin in such a way that the card is horizontal. That balancing point is then the geographic centre.... voila!

Now where do I apply for the Pulitzer prize  :imaposer:
Title: Re: Where is the geographic centre of South Africa?
Post by: Kola? on September 15, 2011, 12:15:33 pm
Fixed

(http://i756.photobucket.com/albums/xx201/KolaDiver/Stuff/thecentre.jpg)
Title: Re: Where is the geographic centre of South Africa?
Post by: Eisbein on September 15, 2011, 12:20:23 pm
So kimberley is the dead centre?  :laughing4:

Makes sense - it is a asshole of Africa.

(Although I might be biased - I've been there in the weather force)

 :biggrin:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 12:24:32 pm
Jan Kempdorp, I've heard
Too far north imho.
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 15, 2011, 12:31:24 pm
Robc - IMHO doesn't cut it with science - we need an absolute undisputed scientific method to determine this.  :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 15, 2011, 12:35:48 pm
Well i certainly got a laugh out of Map Studio....they will come back to me ;D
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 12:45:44 pm
How about:

Cut out a map of SA on a large card (perimeter). Balance the cut-out on a pin in such a way that the card is horizontal. That balancing point is then the geographic centre.... voila!

Now where do I apply for the Pulitzer prize  :imaposer:
Geographic centre not that... ::) :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 15, 2011, 12:47:41 pm
there it is! if someone can superimpose that on a map you can see what town is closest.
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 12:51:18 pm
http://www.mathematische-basteleien.de/geocentre.htm

I prefer #3 as that is cartographicaly correct using longitude/latitude lines.
Wich I approximated in my map I posted.
Will do an actual check on MD's wall map in her office lunch time... :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: JourneyMan on September 15, 2011, 12:54:27 pm
Dibs on organising the first "Bash" there... >:D

Deal! Job is your's for 2012 National Bash. :deal: :biggrin:
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 15, 2011, 12:56:23 pm
Jislaaik Kaalkoejawel, don't you have a day job  :ricky:

Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 15, 2011, 12:56:30 pm
Dibs on organising the first "Bash" there... >:D

Deal! Job is your's for 2012 National Bash. :deal: :biggrin:
Er... :peepwall:....was thinking slightly smaller.....like a dozen guys.... ;D
Journey to the Centre of the Earth...will make a nice T Shirt Slogan
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 15, 2011, 12:57:14 pm
http://www.mathematische-basteleien.de/geocentre.htm

I prefer #3 as that is cartographicaly correct using longitude/latitude lines.
Wich I approximated in my map I posted.
Will do an actual check on MD's wall map in her office lunch time... :mwink:
you cant just draw a box around a random shape and then say the center of the box is the center of the random shape!  :deal:
although, in this case, the two seems to be quite close!
Title: Re: Where is the geographic centre of South Africa?
Post by: JourneyMan on September 15, 2011, 12:59:18 pm
Dibs on organising the first "Bash" there... >:D

Deal! Job is your's for 2012 National Bash. :deal: :biggrin:
Er... :peepwall:....was thinking slightly smaller.....like a dozen guys.... ;D
Journey to the Centre of South Africa...will make a nice T Shirt Slogan

I'll assist. :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 15, 2011, 12:59:45 pm
Jislaaik Kaalkoejawel, don't you have a day job  :ricky:


who wants to know...?  :peepwall:
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 15, 2011, 12:59:57 pm
http://www.mathematische-basteleien.de/geocentre.htm

I prefer #3 as that is cartographicaly correct using longitude/latitude lines.
Wich I approximated in my map I posted.
Will do an actual check on MD's wall map in her office lunch time... :mwink:
you cant just draw a box around a random shape and then say the center of the box is the center of the random shape!  :deal:
Zackly! - Science principle no: 256 - The size of a woman's dress has no bearing on the dimensions or original shape of the contents.  :ricky:
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on September 15, 2011, 01:41:16 pm
Well i certainly got a laugh out of Map Studio....they will come back to me ;D

Hehe. Priceless.  :imaposer: :imaposer:
Title: Re: Where is the geographic centre of South Africa?
Post by: desert dueler on September 15, 2011, 01:53:13 pm
http://thenookbnb.blogspot.com/2008/06/city-of-kimberley-northern-cape-south.html

here you go lads, there is a plaque and all:

(http://2.bp.blogspot.com/_amEarcve75c/SF9l9bFD24I/AAAAAAAAABU/FJm0-9sYDI0/s1600/26082007556.jpg)
Title: Re: Where is the geographic centre of South Africa?
Post by: desert dueler on September 15, 2011, 01:53:57 pm
i will accept 1x invite for the ride to the centre and thanks  :biggrin:

Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on September 15, 2011, 01:54:55 pm
http://thenookbnb.blogspot.com/2008/06/city-of-kimberley-northern-cape-south.html

here you go lads, there is a plaque and all:

(http://2.bp.blogspot.com/_amEarcve75c/SF9l9bFD24I/AAAAAAAAABU/FJm0-9sYDI0/s1600/26082007556.jpg)

Well Done D'Dueller - I knew it had to be somewhere.

Those co-ords go into my list of stop over places.

- Maybe Robc wants to go place a geocache there for us...
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 15, 2011, 01:56:17 pm
Map Studio reckon its around Kimberly.
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on September 15, 2011, 01:58:28 pm
Map Studio reckon its around Kimberly.

Yep - and now you can send them this pic and tell them exactly where.  :thumleft:  :laughing4:
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on September 15, 2011, 02:01:46 pm
It seems to be a fairly well visited spot next to the R64 between Kimberley and Schmidts Drift
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 15, 2011, 02:05:22 pm
Map Studio reckon its around Kimberly.

Yep - and now you can send them this pic and tell them exactly where.  :thumleft:  :laughing4:
Was on it....he's going to print it & pin on the office board! ;D

Now to phone the farmer....Rob!!
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 02:18:19 pm
Thanks... but St Lucia is not the eastern most point afaik. Can make a huge difference in the exact point! :deal:
Plus it was only calculated on one line... I want the North South vectors to be brought in to the calculation as well. >:D
I am getting pretty close... :mwink:

Voila! From my calculations it is -28.59, 24.49 or in other words Barkly West! at the end of Letetsie street! :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 15, 2011, 03:20:32 pm
http://www.mathematische-basteleien.de/geocentre.htm

I prefer #3 as that is cartographicaly correct using longitude/latitude lines.
Wich I approximated in my map I posted.
Will do an actual check on MD's wall map in her office lunch time... :mwink:

You are not considering Marion Island and Prince Edward Island Gough Islands  - both part of South Africa and SOUTH of Agulhas
Gough is WEST of the Greenwich meridian and both are .
From a continental South African perspective, the centroid method (centre of gravity) method is best.

CORRECTION: Gough Island is a UK dependancy with a leased site for a South African Weather Station.

FYI:
Marion Island and Prince Edward Island were claimed for South Africa by a South African Navy force from the HMSAS Transvaal on 29 December 1947 and 4 January 1948 respectively. On 1 October 1948 the annexation was made official when Governor-General Gideon Brand van Zyl signed the Prince Edward Islands Act, 1948. Because the United Kingdom relinquished its claims on the islands to South Africa, no other nation has made a claim on the islands, and they have been occupied continuously since 1948 by South Africa, the status of the islands is not in dispute.

In terms of the Act, the islands fall under the jurisdiction of the Cape Town Magistrate's Court, and South African law as applied in the Western Cape applies on them. The islands are also deemed to be situated within the electoral district containing the Port of Cape Town; as of 2006[update] this is ward 55 of the City of Cape Town.
Title: Re: Where is the geographic centre of South Africa?
Post by: Laban on September 15, 2011, 03:23:14 pm


Not even with seconds to spare!!

 :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Trumpet on September 15, 2011, 03:28:41 pm
I'll check out the veracity of that board with David Morris - the current archeologist at the McGregor Museum whose a family member! However I doubt it's that wrong or that far out - all research indicates it's about 80 km from Bloem going west on the R48, so this looks to be pretty close!
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 03:35:42 pm

You are not considering Marion Island and Gough Islands - both part of South Africa!
Gough is WEST of the Greenwich meridian and both are SOUTH of Agulhas.
From a continental South African perspective, the centroid method (centre of gravity) method is best.
Continental SA is all I am worried about... the ground we can cover on our bikes... not swim! >:D :mwink:
I find the COG method to be irrational, the center of a square/oblong makes trigonometric sense to me... ::)
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 15, 2011, 03:41:02 pm

You are not considering Marion Island and Gough Islands - both part of South Africa!
Gough is WEST of the Greenwich meridian and both are SOUTH of Agulhas.
From a continental South African perspective, the centroid method (centre of gravity) method is best.
Continental SA is all I am worried about... the ground we can cover on our bikes... not swim! >:D :mwink:
I find the COG method to be irrational, the center of a square/oblong makes trigonometric sense to me... ::)
it doesnt work like that. you are not trying to find the center of a shape that has any axis of symmetry. see post #29. SolidWorks doesn't lie!

but hey, maybe my lecturers were wrong....
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 03:46:40 pm
but hey, maybe my lecturers were wrong....
No problem... we can visit all the points using the different calculation styles I suppose. :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 15, 2011, 03:49:57 pm

You are not considering Marion Island and Gough Islands - both part of South Africa!
Gough is WEST of the Greenwich meridian and both are SOUTH of Agulhas.
From a continental South African perspective, the centroid method (centre of gravity) method is best.
Continental SA is all I am worried about... the ground we can cover on our bikes... not swim! >:D :mwink:
I find the COG method to be irrational, the center of a square/oblong makes trigonometric sense to me... ::)

SA may be 'square', but oblong it isn't!  :mwink:
This isn't a new argument - the trig method just appears to be the simplest method working with verifiable numbers.
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 15, 2011, 03:52:03 pm
SA may be 'square', but oblong it isn't!  :mwink:
This isn't a new argument - the trig method just appears to be the simplest method working with verifiable numbers.

then give us your co-ordinates Yoda... ::)
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 15, 2011, 04:18:33 pm
Cool, so the geographic centre is the midpoint between the Latitudinal Northern and Southern boundaries intersected with midpoint of the Western and Eastern Longitudinal edges of a country and not the central point of equal distribution as KillRoy suggested. I withdraw my submission for the Pulitzer  :'(

Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 15, 2011, 04:21:45 pm
if someone would like to visit the centroid of africa.....  :peepwall:
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 15, 2011, 04:27:19 pm
Where is that Southern Chad or Central African Republic?
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 15, 2011, 05:14:19 pm
This just in:

"There is no such thing as the geographical center of any state, country or continent."
-Oscar S. Adams, Senior Mathematician, United States Coast and Geodetic Survey

 ???
Title: Re: Where is the geographic centre of South Africa?
Post by: lonerider on September 15, 2011, 05:46:55 pm
just to throw a cat among the pigeons:

* Has anybody considered the earth's curvature as part of determining the centre of SA? Could well be a few meters underground...

* How much will the "centre" shift by if using different map projections? (http://en.wikipedia.org/wiki/Map_projection for more info)

* Is this centre to be determined by area calculation alone, or should it include mean elevation as a weighting?

Far too many variables for one distinct anwer - Mr Adams might well be technically correct, but for places to seek, visit or explore, this dilemma is a traveller's manna! :)
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 15, 2011, 06:01:23 pm
That's why I suggested that the midway between W+E and N+S appears to be the simplest method.
But we need the TRUE Longitude and latitude values for the W, E, N + S points.
I have tried using Mapsource and Google Earth, but I arrive at a midpoint NE of Barkly West,
near the farm homestead Kilmoray.
 ???
Title: Re: Where is the geographic centre of South Africa?
Post by: JourneyMan on September 15, 2011, 08:24:41 pm
Dibs on organising the first "Bash" there... >:D

Deal! Job is your's for 2012 National Bash. :deal: :biggrin:
Er... :peepwall:....was thinking slightly smaller.....like a dozen guys.... ;D
Journey to the Centre of the Earth...will make a nice T Shirt Slogan

You are of the hook it seems.

Might take another year before consensus is reached. :biggrin:
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 16, 2011, 06:49:12 am
just to throw a cat among the pigeons:

* Has anybody considered the earth's curvature as part of determining the centre of SA? Could well be a few meters underground...

* How much will the "centre" shift by if using different map projections? (http://en.wikipedia.org/wiki/Map_projection for more info)

* Is this centre to be determined by area calculation alone, or should it include mean elevation as a weighting?

Far too many variables for one distinct anwer - Mr Adams might well be technically correct, but for places to seek, visit or explore, this dilemma is a traveller's manna! :)

Pigeon pie comes to mind  ;D

You are spot on in that the projections of maps may be distorted from a representation perspective. That would depend on the projection method used.

If one looks for the shortest distance between two spherical points, then the elevation would become evident (i.e. below the surface).

One should therefore use a spherical surface formulae (ref: http://en.wikipedia.org/wiki/Geographical_distance}

As a result of the Earth not being a sphere and having a bulge around the equator, makes the Earth an ellipsoid. So more accurately one needs to use an Elipsoidal-surface formulae to get the approximated distance over great distances. There are several documented methods - Vincenty's Bowring's and Lambert's formulae.

For interest's sake take a look at Vincenty's formulae - http://en.wikipedia.org/wiki/Vincenty%27s_formulae

Wikipedia then goes further to say ...

Quote
The systems are needed because the earth is not a perfect sphere. Neither is the earth an ellipsoid. This can be verified by differentiating the equation for an ellipsoid and solving for dy/dx. It is a constant multiplied by x/y. Then derive the force equation from the centrifugal force acting on an object on the earth's surface and the gravitational force. Switch the x and y components and multiply one of them by negative one. This is the differential equation which when solved will yield the equation for the earth's surface. This is not a constant multiplied by x/y. Note that the earth's surface is also not an equal-potential surface, as can be verified by calculating the potential at the equator and the potential at a pole. The earth is an equal force surface. A one kilogram frictionless object on the ideal earth's surface does not have any force acting upon it to cause it to move either north or south. There is no simple analytical solution to this differential equation. A power series solution using three terms when substituted into this differential equation bogs down a TI-89 calculator and yields about three hundred terms after about five minutes.

This is enough to make a monkey fuck a pineapple.  ::)

But when one uses Lat and Long coordinates and GPS coordinates, then presentation is irrelevant.

So for the sake of DS motorcycle enjoyment, the simplest method should be applied: (E.point - W.point) /2 + W.point = Mid Horizontal .point
and; (N.point - S.point) /2 + S.point = Mid Vertical .point

Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 07:51:15 am
just to throw a cat among the pigeons:

* Has anybody considered the earth's curvature as part of determining the centre of SA? Could well be a few meters underground...

* How much will the "centre" shift by if using different map projections? (http://en.wikipedia.org/wiki/Map_projection for more info)

* Is this centre to be determined by area calculation alone, or should it include mean elevation as a weighting?

Far too many variables for one distinct anwer - Mr Adams might well be technically correct, but for places to seek, visit or explore, this dilemma is a traveller's manna! :)
ergo my suggestion that all methods be used and all centres be visited. :mwink: :thumleft:
I like keeping things simple and will start planning a visit to my calculated point in Barkly West as well as the Koppie mentioned. :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 07:53:10 am
Might take another year before consensus is reached. :biggrin:
this is like the "What oil to use", "What is the best DS bike" and a plethora of other debates it seems... but doing them all will be fun. :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 16, 2011, 07:53:29 am
jislaaik, this is getting way too complicated! Rob, draw a box and get the center!  :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 16, 2011, 08:12:06 am
We don't one day want to rock up in Kimberly to have a local yokel laugh his his head off while pointing out that the Koppie is in actual fact NOT the centre of RSA....

Now to find a map i can draw lines all over... :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: ClimbingTurtle on September 16, 2011, 08:20:00 am
How would one find the geographic centre of South Africa? The crossing point between the most Northern/Southern & Eastern/Western points in SA?

That would be S27.89008 E25.62496


I like this one best - mainly because my next multi-day ride is going to pass within about 15-20km of the noted centre point. Based purely on that, I am going to try and visit it, just in case it makes the list of one-of-many-centre-points of SA.....!
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 08:20:24 am
jislaaik, this is getting way too complicated! Rob, draw a box and get the center!  :mwink:
I did! :deal: and got the co-ordinates and even a Google picture of the location of the point (located near the graveyard in the location).  :deal:
Now to set the date... :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 08:24:16 am
How would one find the geographic centre of South Africa? The crossing point between the most Northern/Southern & Eastern/Western points in SA?

That would be S27.89008 E25.62496


I like this one best - mainly because my next multi-day ride is going to pass within about 15-20km of the noted centre point. Based purely on that, I am going to try and visit it, just in case it makes the list of one-of-many-centre-points of SA.....!
I beg to differ... I calculated mine from the exact NS/EW demarcators and it is S28.59/E24.49. :deal: :mwink:
But I will add this to the list! :imaposer:
The more points the more fun I believe :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: tok-tokkie on September 16, 2011, 09:03:32 am
This is the method I prefer (from my earlier post):
Quote
2. Center of Gravity method, which I prefer.  Get a map of SA & stick it to thick cardboard.  Cut around the edge of SA with an Exacto knife & cut out Lesotho so just the SA landmass remains.  Stick a pin through near Messina & pin to a vertical board, must be free to swing.  Hang a piece of cotton with small weight from pin.  Draw line where cotton thread lies.  Repeat near Richards Bay & Alexander Bay.  3 lines should cross at a point = CofG of the cardboard.

If you stuck a pin through that point & pinned it to a vertical board, gave it a spin there would be no heavy point so it would stop with any point at the bottom.  The thing is balanced so, to me, that is the best center.  Theoretically could also balance it on a pin stuck through there.

My method 1 was the NS & EW mid point idea but the thing would be out of balance on the pin test.
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 16, 2011, 09:16:37 am
This is the method I prefer (from my earlier post):
Quote
2. Center of Gravity method, which I prefer.  Get a map of SA & stick it to thick cardboard.  Cut around the edge of SA with an Exacto knife & cut out Lesotho so just the SA landmass remains.  Stick a pin through near Messina & pin to a vertical board, must be free to swing.  Hang a piece of cotton with small weight from pin.  Draw line where cotton thread lies.  Repeat near Richards Bay & Alexander Bay.  3 lines should cross at a point = CofG of the cardboard.

If you stuck a pin through that point & pinned it to a vertical board, gave it a spin there would be no heavy point so it would stop with any point at the bottom.  The thing is balanced so, to me, that is the best center.  Theoretically could also balance it on a pin stuck through there.

My method 1 was the NS & EW mid point idea but the thing would be out of balance on the pin test.
yes! :thumleft:

cut out my green RSA in post #29 and stick a pin through the pink dot - it will (should) be balanced!
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 09:21:50 am
The thing is there is no "standard" it seems. So what I propose is a "Pin the donkey" trip to visit all the proposals and find any donkeys along the way... :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Bie on September 16, 2011, 09:28:34 am
Quote
cut out my green RSA in post #29 and stick a pin through the pink dot - it will (should) be balanced!

Please post the map you used to get your green RSA map as the projection differs from the overlay I have, meaning the point will not be exact on my overlay map.
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 09:32:10 am
Quote
cut out my green RSA in post #29 and stick a pin through the pink dot - it will (should) be balanced!

Please post the map you used to get your green RSA map as the projection differs from the overlay I have, meaning the point will not be exact on my overlay map.
Yikes... so there is not even a "standard" RSA!  :deal: :mwink: :imaposer:
Title: Re: Where is the geographic centre of South Africa?
Post by: Groenie on September 16, 2011, 09:33:52 am
You need one of these.

(http://infolab.stanford.edu/pub/voy/museum/pictures/display/pl1.jpg)

Last time I saw one was at varsity, many moons ago. It's a mechanical integrator and you trace the 'pin' around the edge of an object to find all sorts of wonderful (useless) info about it.

Here's more

http://infolab.stanford.edu/pub/voy/museum/pictures/display/4-4-Integrator.htm
Title: Re: Where is the geographic centre of South Africa?
Post by: Bie on September 16, 2011, 09:35:33 am
As long as Eskom is doing their part we are way beyond those nowadays. Only for blackout days.  :imaposer:
Title: Re: Where is the geographic centre of South Africa?
Post by: Groenie on September 16, 2011, 09:36:05 am
I found more - http://www.lasico.com/index.html
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 16, 2011, 09:37:04 am
i found an Autocad dwg file of the outlines of african countries and used the RSA bit from that. its probably not a very accurate outline, but i didnt use an actual map - dont have the software for that.
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on September 16, 2011, 09:38:45 am
If there is more than 1 centre point, we could plot those (which will be only a few) and then get to the centre of the centre  :biggrin:

Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 09:42:14 am
That's why I suggested that the midway between W+E and N+S appears to be the simplest method.
But we need the TRUE Longitude and latitude values for the W, E, N + S points.
I have tried using Mapsource and Google Earth, but I arrive at a midpoint NE of Barkly West,
near the farm homestead Kilmoray.
 ???
That is near my suggested point too.
I went in on Google maps and plotted points for NSWE vectors and then calculated the difference between the lat. long. divided by 2 then added that to one of lesser co ordinates and arrived at my rough RV. But as you say a 1/2 degree in any direction is quite a difference when plotted.
Do you have the co ordinates for your point?
Lets get as many as possible and then divide those results too! :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 09:43:12 am
If there is more than 1 centre point, we could plot those (which will be only a few) and then get to the centre of the centre  :biggrin:


and plot the ride to visit them all! :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 16, 2011, 04:51:23 pm
That is near my suggested point too.
I went in on Google maps and plotted points for NSWE vectors and then calculated the difference between the lat. long. divided by 2 then added that to one of lesser co ordinates and arrived at my rough RV. But as you say a 1/2 degree in any direction is quite a difference when plotted.
Do you have the co ordinates for your point?
Lets get as many as possible and then divide those results too! :mwink:

I did exactly the same and arrived at the point:

Latitude: -28.47991493 Longitude : 24.67269332
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 16, 2011, 05:23:06 pm
That is near my suggested point too.
I went in on Google maps and plotted points for NSWE vectors and then calculated the difference between the lat. long. divided by 2 then added that to one of lesser co ordinates and arrived at my rough RV. But as you say a 1/2 degree in any direction is quite a difference when plotted.
Do you have the co ordinates for your point?
Lets get as many as possible and then divide those results too! :mwink:

I did exactly the same and arrived at the point:

Latitude: -28.47991493 Longitude : 24.67269332
also good... just west of my first picture (the dam and sheep) :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: tok-tokkie on September 17, 2011, 10:16:34 am
That is near my suggested point too.
I went in on Google maps and plotted points for NSWE vectors and then calculated the difference between the lat. long. divided by 2 then added that to one of lesser co ordinates and arrived at my rough RV. But as you say a 1/2 degree in any direction is quite a difference when plotted.
Do you have the co ordinates for your point?
Lets get as many as possible and then divide those results too! :mwink:

I did exactly the same and arrived at the point:

Latitude: -28.47991493 Longitude : 24.67269332
If you did hat on an L shaped country like Namibia your 'center' point will be very far to one side which is why I think the center of gravity method is much better.
Title: Re: Where is the geographic centre of South Africa?
Post by: Sláinte Mhaith on September 17, 2011, 10:57:44 am
That is near my suggested point too.
I went in on Google maps and plotted points for NSWE vectors and then calculated the difference between the lat. long. divided by 2 then added that to one of lesser co ordinates and arrived at my rough RV. But as you say a 1/2 degree in any direction is quite a difference when plotted.
Do you have the co ordinates for your point?
Lets get as many as possible and then divide those results too! :mwink:

I did exactly the same and arrived at the point:

Latitude: -28.47991493 Longitude : 24.67269332
If you did hat on an L shaped country like Namibia your 'center' point will be very far to one side which is why I think the center of gravity method is much better.

+1 Those methods can't be correct.
Title: Re: Where is the geographic centre of South Africa?
Post by: Sláinte Mhaith on September 17, 2011, 10:58:44 am
http://en.wikipedia.org/wiki/Geographical_centre

In geography, the centroid of the two-dimensional shape of region of the Earth's surface is often known as its geographical centre. There has long been debate over the methods of calculation of the geographical centres of various countries and regions, such as whether to include offshore islands, and in that case, if the islands should be moved towards the mainland, making it possible to build a connected 2D model of the country and identify the geographical centre as the centre of gravity (equilibrium point) using a needle. An alternative to defining the geographical centre as the centroid is to define it as the point farthest from the boundary of the country (either the sea, or, in the case of constituent countries, a land border). These methods give quite different answers.
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 18, 2011, 05:35:39 am
This is what I calculate with some pictures to illustrate my sources....

Western Point  28°37'52.00"S  16°27'20.00"E
Eastern Point  26°51'27.52"S  32°53'28.86"E
Norther Point  22° 7'30.01"S  29°39'25.80"E
Southern Point  34°50'0.00"S  20° 0'0.00"E

Centre point  28°28'45.00"S  24°40'23.30"E

Distance from Kimberly 28 kms NNW (343.68°)

The centre point is 12km from the N12 and 5kms after crossing the Vaal River.

Looks like a few quarries around with some farming in the general area.  >:D





Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 19, 2011, 06:46:20 pm
Pretty close to where I got, but you're a teeny bit East.

Wikipedia gives Cape Agulhas as 34 50 00S and 20 00 09.15 E
Title: Re: Where is the geographic centre of South Africa?
Post by: Sláinte Mhaith on September 19, 2011, 08:24:35 pm
http://en.wikipedia.org/wiki/Geographical_centre
In geography, the centroid of the two-dimensional shape of region of the Earth's surface is often known as its geographical centre.

Didn't finish my 5c the other day:


Geographical centre ------> Centroid of 2 dimensional shape

Centroid --------> (http://upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Triangle.Centroid.svg/220px-Triangle.Centroid.svg.png)




This is not a north/south and east west method. Therefore I agree with kaalkoejawel and Tok Tokkie.



For an odd shape this method seems practical:

Plumb line method

The centroid of a uniform two-dimensional lamina, such as (a) below, may be determined, experimentally, by using a plumbline and a pin to find the center of mass of a thin body of uniform density having the same shape. The body is held by the pin inserted at a point near the body's perimeter, in such a way that it can freely rotate around the pin; and the plumb line is dropped from the pin (b). The position of the plumbline is traced on the body. The experiment is repeated with the pin inserted at a different point of the object. The intersection of the two lines is the centroid of the figure (c).

(http://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Center_gravity_0.svg/147px-Center_gravity_0.svg.png) (http://upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Center_gravity_1.svg/183px-Center_gravity_1.svg.png) (http://upload.wikimedia.org/wikipedia/commons/thumb/0/05/Center_gravity_2.svg/157px-Center_gravity_2.svg.png)
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 19, 2011, 08:49:13 pm
 ::) Yup, that's the other way that it is done.
Anyone care to cut up a big map and hang it up from 2 or 3 points?
Remember to cut Lesotho out first too.
Having done so, anyone have an idea how we would find the exact coordinates of the crossed lines... ?  ::)
Title: Re: Where is the geographic centre of South Africa?
Post by: Sláinte Mhaith on September 19, 2011, 09:20:47 pm
::) Yup, that's the other way that it is done.
Anyone care to cut up a big map and hang it up from 2 or 3 points?
Remember to cut Lesotho out first too.
Having done so, anyone have an idea how we would find the exact coordinates of the crossed lines... ?  ::)

Kaalkoejawel has done it electronically, although his map (on page 2) is not very accurate.
His point seems to be just east of Kimberley although it is difficult to transpose.
If you really want to be accurate you should probably also include the islands.
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 20, 2011, 02:29:12 am
Pretty close to where I got, but you're a teeny bit East.

Wikipedia gives Cape Agulhas as 34 50 00S and 20 00 09.15 E

FM Isn't the important coord the Southern one - 34 50 00S  - the East point should (20 00 09.15 E) be ignored as the Far Eastern point is the important one ?
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 20, 2011, 06:04:42 pm
Pretty close to where I got, but you're a teeny bit East.

Wikipedia gives Cape Agulhas as 34 50 00S and 20 00 09.15 E

FM Isn't the important coord the Southern one - 34 50 00S  - the East point should (20 00 09.15 E) be ignored as the Far Eastern point is the important one ?

 :eek7: You're right of course!

(FM you dumb clutz!)  :-[
Title: Re: Where is the geographic centre of South Africa?
Post by: Tommy Transalp on September 20, 2011, 07:25:12 pm
With GPS co-ords... Let's organise a national bash there sometime (wherever that may be!)
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on September 20, 2011, 08:24:12 pm
and the final co-ords are?  :)
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 21, 2011, 06:25:48 am
In GPS lingo I make the Centre point  25 Y0031989 X3151554

In Long & Lat - 28°28'45.00"S  24°40'23.30"E
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 21, 2011, 08:09:05 am

Plumb line method

The centroid of a uniform two-dimensional lamina, such as (a) below, may be determined, experimentally, by using a plumbline and a pin to find the center of mass of a thin body of uniform density having the same shape. The body is held by the pin inserted at a point near the body's perimeter, in such a way that it can freely rotate around the pin; and the plumb line is dropped from the pin (b). The position of the plumbline is traced on the body. The experiment is repeated with the pin inserted at a different point of the object. The intersection of the two lines is the centroid of the figure (c).
thats interesting! i didnt know that!

and yes, the map i used is a very rough outline, so it will be a bit off. i couldnt find a more accurate one in dwg format.
Title: Re: Where is the geographic centre of South Africa?
Post by: MildDog on September 21, 2011, 10:58:00 am
F**k you okes have made this way complicated.

Just pick a spot somewhere in the middle and ride there :)
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 21, 2011, 11:11:48 am
F**k you okes have made this way complicated.

Just pick a spot somewhere in the middle and ride there :)
My suggestion is Barkly West... find a place to stay and then explore the different points mentioned from there.
AFAIK there are one or two good campsites on the river.
I feel like taking a ride out there this weekend... :deal:
Title: Re: Where is the geographic centre of South Africa?
Post by: GRIM on September 21, 2011, 02:49:55 pm
My GIS software has a "Coordinaes of centroid" function...
but it's far more fun watching you guys work it out...
 >:D
Title: Re: Where is the geographic centre of South Africa?
Post by: Captain Morgan on September 21, 2011, 04:00:13 pm
My GIS software has a "Coordinaes of centroid" function...
but it's far more fun watching you guys work it out...
 >:D
Come on Grim, put us out of our misery then, please.

Cheers
Title: Re: Where is the geographic centre of South Africa?
Post by: Dirt Junkie on September 21, 2011, 05:54:12 pm
S29 03.478 E26 13.538 was thought to be the center of south africa by Adolf Hitler
Legend has it that the house was intended as a refuge for Adolf Hitler in case he needed
to flee from World War II. Even the architecture is modelled on Hitler’s holiday house,
Berghof, in the Obersalzberg in Germany
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 22, 2011, 04:37:14 am
Very interesting DJ, That's 6kms from Bloem. They didn't have Google Earth and GPS back then, so Bloem (about 170kms from the current Centroid) is not a bad take. Considering the rendition of Maps were very rough back then and borders shifted constantly.

RobC, Good Idea to explore using Barkley West as a base.

You are based in the OFS so presumably not too far. Us Gautengers are not too far - around 450kms away as the crow flies.

I would be keen to hook up for a reckie around and plant a WD centroid marker. This weekend is a bit soon for me but next weekend or the one thereafter would suite me better.

The tar road to Barkley West from Jhb is very boring, so I'm studying some dirt routes to make the trip more interesting.

Who's keen to explore the surrounds and plant a marker?
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 22, 2011, 08:21:18 am
Also keen but this weekend is already booked.

I will take some pics of "Berghof" or Hitlers house though... a few years ago it was used as a nightclub but due to its location the sound of music tended to travel quite far at night... the folks at Hillsborough had it closed down, it may be a guest house now.
http://www.olivechefschool.co.za/publications_and_other/Berghof.pdf
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 22, 2011, 12:26:42 pm
Berghof Restaurant looks very interesting. Is the restaurant going? I tried to call the number but says it does not exist.

I wouldn't mind having a meal there - do you think they would mind some dusty bikers?  :ricky:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 22, 2011, 12:54:14 pm
Berghof Restaurant looks very interesting. Is the restaurant going? I tried to call the number but says it does not exist.

I wouldn't mind having a meal there - do you think they would mind some dusty bikers?  :ricky:
They moved to Woodlands estate, only realized that after posting... the website is out of date! :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 22, 2011, 01:33:52 pm
A Journey to the centre of SA could be an adventure with a difference. I've never had the pleasure of riding that part of SA. What can one expect?

The timing might be bad with so many upcoming events - GS ECO challenge 6-9 Oct, CABC 22-25th Sep (this weekend)  and the WD Annual Bash Date: 14-16 October 2011.

Who can squeeze in a weekend adventure?

Title: Re: Where is the geographic centre of South Africa?
Post by: XTFREAK on September 22, 2011, 01:48:17 pm
sounds like a jol, leave staurday morning and back sunday arvie to jhb
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 22, 2011, 02:16:36 pm
A Journey to the centre of SA could be an adventure with a difference. I've never had the pleasure of riding that part of SA. What can one expect?

The timing might be bad with so many upcoming events - GS ECO challenge 6-9 Oct, CABC 22-25th Sep (this weekend)  and the WD Annual Bash Date: 14-16 October 2011.

Who can squeeze in a weekend adventure?


well if you make it the 5th of Nov you can try out our straight line rally here at Bloemfontein Off Road Club... and see the fireworks later that night.
http://www.wilddog.za.net/forum/index.php?topic=77575.0
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 23, 2011, 05:22:59 am
That could be a plan. :thumleft:

Would then suggest taking off the Friday to get down (using the long way down method - offroad where possible and practical for more cross country adventure). Saturday doing the Rally and Sunday morning find the Centroid plant a marker, have brunch and then head back around midday.
Title: Re: Where is the geographic centre of South Africa?
Post by: XTFREAK on September 23, 2011, 11:34:11 am
Might be nice if each person trying to find the spot can bring a rock of about 100mm dia from their area to plant at the spot, just to show a unity from every area possible in the country???
Title: Re: Where is the geographic centre of South Africa?
Post by: Lourens ツ on September 23, 2011, 11:43:02 am
Might be nice if each person trying to find the spot can bring a rock of about 100mm dia from their area to plant at the spot, just to show a unity from every area possible in the country???

If there are few spots that could be the right one your load is going to get heavy!  ;D

But I think its a great idea.  :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 23, 2011, 12:43:35 pm
Don't they have enough Rocks in the Free State   :peepwall:

Title: Re: Where is the geographic centre of South Africa?
Post by: roxenz on September 26, 2011, 02:44:16 pm
Well, given that the Bushveld Complex (or at least the mafic part) is much denser than the sediments of the western Cape and karoo, I reckon the centroid should be about Randfontein.  Isn't that what they use to calculate the road levy for wheat?

 ;)
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 26, 2011, 02:45:15 pm
Berghof as it is today... just a big residence now.
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 26, 2011, 02:47:05 pm
Well, given that the Bushveld Complex (or at least the mafic part) is much denser than the sediments of the western Cape and karoo, I reckon the centroid should be about Randfontein.  Isn't that what they use to calculate the road levy for wheat?

 ;)
Too many variables in the COG method... it goes against Occams Razor.  ::) :mwink:
The simplest idea is the easiest to use. :peepwall:
Title: Re: Where is the geographic centre of South Africa?
Post by: roxenz on September 26, 2011, 03:12:35 pm
No Rob, we need something contestable, otherwise the forum would get boring!   ;D

Come on GRIM, spoeg dit uit!!!
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 27, 2011, 05:15:46 am
RobC, Berghoff looks pretty locked down - maybe ex gestapo headquarters :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 27, 2011, 08:25:04 am
RobC, Berghoff looks pretty locked down - maybe ex gestapo headquarters :mwink:
:imaposer: Jawohl...
Not used as a chef school at all now! :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: LeonDude on September 29, 2011, 06:31:27 pm
You can’t use the plumbline method for this, reason being scale. Even if you print a massive 6 x 6 meter big map of SA, if you pin it up, you would never with the eye get the position of the pin right.
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 29, 2011, 07:16:24 pm
Agree, you would need a precise projection of the spherical shape as a starting point making your chances of getting to a pinpoint location more of an art than a science.
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on September 29, 2011, 07:45:59 pm
I started this thread and have seen it develop and also learned a moerse lot about how to do this geo centering.  :thumleft:

So do we have a (close to) final answer?

Because next, I would like to know the individual provinces as well.  I am itching for a senseless trip to all these waypoints. Maybe I will go plant a geocache at each...
Title: Re: Where is the geographic centre of South Africa?
Post by: Sláinte Mhaith on September 29, 2011, 09:23:14 pm
You can’t use the plumbline method for this, reason being scale. Even if you print a massive 6 x 6 meter big map of SA, if you pin it up, you would never with the eye get the position of the pin right.

Which position? According to the method you can pin it in any position as long as it is close to the border?

The map can rotate and will balance with half the weight on the left and half on the right of the plumb line.
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 30, 2011, 06:12:35 am
Unless you feel nostalgic, why would you want to use paper and string when you've got Google Earth with all the spherical locating capability down to seconds (metres) ?
Title: Re: Where is the geographic centre of South Africa?
Post by: LeonDude on September 30, 2011, 07:31:46 am
You can’t use the plumbline method for this, reason being scale. Even if you print a massive 6 x 6 meter big map of SA, if you pin it up, you would never with the eye get the position of the pin right.

Which position? According to the method you can pin it in any position as long as it is close to the border?

The map can rotate and will balance with half the weight on the left and half on the right of the plumb line.
Any position, it's all about scale. If you print a map of SA on something like an A4 paper, your scale would be quite a couple of kilometers to the millimeter. The hole your pin makes would be about a millimeter. Therefore, your position would be out by many kilometers.
Title: Re: Where is the geographic centre of South Africa?
Post by: LeonDude on September 30, 2011, 07:33:05 am
These guys don’t want to know in which province or town, they want to know with accuracy as in coords. The plumb line method just cannot give you this.
Title: Re: Where is the geographic centre of South Africa?
Post by: Sláinte Mhaith on September 30, 2011, 08:04:46 am
Any position, it's all about scale. If you print a map of SA on something like an A4 paper, your scale would be quite a couple of kilometers to the millimeter. The hole your pin makes would be about a millimeter. Therefore, your position would be out by many kilometers.

Aaahhh, the pinhole of the centre point. Now I understand.

The guys who could calculate it electronically lost interest in this thread.
Title: Re: Where is the geographic centre of South Africa?
Post by: The Rock on September 30, 2011, 08:06:18 am
jislaaik! have you guys still not made up your minds?
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 30, 2011, 08:18:35 am
I still like the simple method I proposed... :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on September 30, 2011, 02:02:13 pm
jislaaik! have you guys still not made up your minds?

Don't be silly this is done by committee  :ricky:

Things take time - just like our government  :biggrin:
Title: Re: Where is the geographic centre of South Africa?
Post by: XTFREAK on September 30, 2011, 10:46:13 pm
Maybe we should start another thread to discuss starting a thread to find the spot?? Just asking?
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on October 01, 2011, 02:52:00 am
Maybe we should start another thread to discuss starting a thread to find the spot?? Just asking?
Yeah, then we can find the common spot of all of the threads to find the real thread  ;D
Title: Re: Where is the geographic centre of South Africa?
Post by: GRIM on October 05, 2011, 12:05:57 pm


The guys who could calculate it electronically lost interest in this thread.

 :lamer:

Here you go...  ;D

PROVNAME   CentroidX                          CentroidY
Eastern Cape   26° 26' 46.898" E    32° 9' 14.499" S
Free State           26° 52' 2.150" E      28° 36' 51.852" S
Gauteng           28° 11' 51.183" E   26° 4' 31.572" S
KwaZulu-Natal   30° 44' 54.812" E   28° 42' 59.707" S
Mpumalanga   30° 17' 56.335" E   25° 52' 25.144" S
Northern Cape   21° 24' 10.114" E   29° 27' 12.258" S
Limpopo           29° 17' 23.148" E   23° 47' 7.207" S
North West   25° 32' 54.452" E   26° 16' 13.495" S
Western Cape   20° 36' 57.737" E   33° 0' 52.372" S
South Africa   25° 5' 38.087" E           28° 59' 43.146" S
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on October 05, 2011, 12:08:38 pm
Grim, jou doring  :thumleft: :thumleft:

Who will be the first to visit the lot?

(If they are all accessible...  :peepwall: )
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on October 05, 2011, 12:58:35 pm
SA 25° 5' 38.087" E           28° 59' 43.146" S

Is near Paardeberg, scene of the Boer War battle. Been down that bit of dirt when I did the "Follow the river" ride. :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on October 05, 2011, 01:00:08 pm
Grim, jou doring  :thumleft: :thumleft:

Who will be the first to visit the lot?

(If they are all accessible...  :peepwall: )
Gooi the co-ord on Googlemaps... works lekker! :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on October 05, 2011, 01:01:08 pm


The guys who could calculate it electronically lost interest in this thread.

 :lamer:

Here you go...  ;D

PROVNAME   CentroidX                          CentroidY
Eastern Cape   26° 26' 46.898" E    32° 9' 14.499" S
Free State           26° 52' 2.150" E      28° 36' 51.852" S
Gauteng           28° 11' 51.183" E   26° 4' 31.572" S
KwaZulu-Natal   30° 44' 54.812" E   28° 42' 59.707" S
Mpumalanga   30° 17' 56.335" E   25° 52' 25.144" S
Northern Cape   21° 24' 10.114" E   29° 27' 12.258" S
Limpopo           29° 17' 23.148" E   23° 47' 7.207" S
North West   25° 32' 54.452" E   26° 16' 13.495" S
Western Cape   20° 36' 57.737" E   33° 0' 52.372" S
South Africa   25° 5' 38.087" E           28° 59' 43.146" S

That is 10 centroids to plot and visit then! Great stuff! :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: tok-tokkie on October 05, 2011, 05:23:29 pm
You can’t use the plumbline method for this, reason being scale. Even if you print a massive 6 x 6 meter big map of SA, if you pin it up, you would never with the eye get the position of the pin right.
Well the electronic version does it that way.  Gives 25°  5'    38 " E   28° 59'  43" S
Halving the lat & long extremities gives                   24°  40'  23"  E   28° 28'  45" S
Plumbline is the method I prefer.
Title: Re: Where is the geographic centre of South Africa?
Post by: Lourens ツ on October 05, 2011, 05:24:44 pm
Here are Grim's points in a gpx file.  :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: Bie on October 05, 2011, 05:25:24 pm
Ek sien jou punt is taamlik meer Oos as die ander, nou wonder ek net, het jy onthou om Lesotho uit te sny?
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on October 05, 2011, 06:03:32 pm
Here are Grim's points in a gpx file.  :thumleft:

Thanks Lourens

I see most point are close to a road and fairly accessible.

Interesting will be the one in Limpopo  O0 O0 O0
Title: Re: Where is the geographic centre of South Africa?
Post by: Vatso! on January 24, 2012, 04:36:40 pm
Gents, I know I'm a bit late with this info but the official center of RSA is a small station known as Emmaus - halfway between Petrusburg and Kimberley. It seems as if Grim has the spot covered!
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on January 24, 2012, 04:40:50 pm
So het iemand al foto's gaan neem?
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on March 29, 2012, 12:39:47 pm
Has anyone marked the Centroid yet. I'm heading there on my way to Lesotho from Prieska. I thing that some token need to be left there to mark the spot. Any suggestions:

- Planting a Tree - and tag it;
- Plant a Flag with a WD paw;
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on March 29, 2012, 02:32:30 pm
I plotted the centroids.
I also plotted practical centroids that you can identify on the ground.
Happy ride...!

Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on March 29, 2012, 05:30:24 pm
That is very cool Fudmucker - I would like to see some pictures as folks pass by these points.

B.t.w please explain the difference between centroid and practical centroid
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on March 29, 2012, 07:43:32 pm
That is very cool Fudmucker - I would like to see some pictures as folks pass by these points.

B.t.w please explain the difference between centroid and practical centroid

The centroid is the deduced geographic centroid.
Say, for example, it is in the middle of a dam, or a factory, or a golf course...?
How do you identify the exact position on the ground...?
So I determined a nearby point that is easily found and verified - a street intersection, a bridge over a river, etc - and called them the "Practical Centroid".
That saves you mucking about in the marsh with your GPS until the co-ordinates match.  ;D
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on March 29, 2012, 07:46:01 pm
That is very cool Fudmucker - I would like to see some pictures as folks pass by these points.

B.t.w please explain the difference between centroid and practical centroid

The centroid is the deduced geographic centroid.
Say, for example, it is in the middle of a dam, or a factory, or a golf course...?
How do you identify the exact position on the ground...?
So I determined a nearby point that is easily found and verified - a street intersection, a bridge over a river, etc - and called them the "Practical Centroid".
That saves you mucking about in the marsh with your GPS until the co-ordinates match.  ;D

 :thumleft: I thought so, but the Freestate one take us even deeper into a marsh next to a dam - that's what confused me.
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on March 30, 2012, 05:32:43 am
I plotted the centroids.
I also plotted practical centroids that you can identify on the ground.
Happy ride...!



Thanks Fud, I've loaded that point. :thumleft:

What remains is to plant something to mark the spot, take some pics :biggrin:
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on March 30, 2012, 06:27:35 am
Heimer, that FS Practical Centroid should be at a 270+degree corner in the S482.
Perhaps if you zoom in a little...?  
Title: Re: Where is the geographic centre of South Africa?
Post by: J-dog on March 30, 2012, 06:41:40 am
Fock 'n winters claim it's 22 miles NW of Kimberley, and I'll have to go with them. They sound authoritative.
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on March 30, 2012, 07:35:33 am
Here's the SA Centroid's location ...

Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on March 30, 2012, 02:45:07 pm
Heimer, that FS Practical Centroid should be at a 270+degree corner in the S482.
Perhaps if you zoom in a little...?  

That is already zoomed in ....  ???
Title: Re: Where is the geographic centre of South Africa?
Post by: Sláinte Mhaith on March 30, 2012, 03:07:09 pm
:thumleft: I thought so, but the Freestate one take us even deeper into a marsh next to a dam - that's what confused me.

???
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on March 30, 2012, 03:18:46 pm
Fock 'n winters claim it's 22 miles NW of Kimberley, and I'll have to go with them. They sound authoritative.

Anyone with the name Fock'n Winters should be ignored.
Now if it was Fock'n Somers I would agree...  :mwink:
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on March 30, 2012, 03:47:58 pm
:thumleft: I thought so, but the Freestate one take us even deeper into a marsh next to a dam - that's what confused me.

???


??? indeed. I open it with mapsource and that is where it takes me - next to a dam.
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on March 30, 2012, 03:58:54 pm
It was plotted with Mapsource...  :deal:
Perhaps you have a different version?
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on March 30, 2012, 04:04:43 pm
It was plotted with Mapsource...  :deal:
Perhaps you have a different version?

Mapsource Version 6.16.3.

Both Tracks4Africa 11.10.04 and SA topo 2011.3 show it next to that dam

All the other spots seem correct
Title: Re: Where is the geographic centre of South Africa?
Post by: Sláinte Mhaith on March 30, 2012, 05:03:39 pm
It was plotted with Mapsource...  :deal:
Perhaps you have a different version?

Mapsource Version 6.16.3.

Both Tracks4Africa 11.10.04 and SA topo 2011.3 show it next to that dam

All the other spots seem correct

Mapsource version will not make a difference but the map version might.
The points on both images above seem a similar distance from the road taking scale into account. Mine just shows an additional road while yours show a bigger dam.
Did you use T4A for that screenshot? SA topo should show the same road as I have.
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on March 30, 2012, 05:12:03 pm
It was plotted with Mapsource...  :deal:
Perhaps you have a different version?

Mapsource Version 6.16.3.

Both Tracks4Africa 11.10.04 and SA topo 2011.3 show it next to that dam

All the other spots seem correct

Mapsource version will not make a difference but the map version might.
The points on both images above seem a similar distance from the road taking scale into account. Mine just shows an additional road while yours show a bigger dam.
Did you use T4A for that screenshot? SA topo should show the same road as I have.

Yes it was done with t4a

Sa topo is correct - I just checked again  :thumleft:

Title: Re: Where is the geographic centre of South Africa?
Post by: Laban on April 08, 2012, 06:20:44 pm
Bakenkop, next to the road, restricted
Title: Re: Where is the geographic centre of South Africa?
Post by: Laban on April 08, 2012, 06:23:30 pm
From the verge
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on April 08, 2012, 06:27:31 pm
1 down !!!

Nice Laban.  :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: Laban on April 08, 2012, 06:33:27 pm
Letsie Street
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on April 08, 2012, 06:40:12 pm
Ek het al gewonder of van die mense 'n 'middle of the world' spaza winkeltjie sou oopmaak as hulle weet waar hulle woon?
Title: Re: Where is the geographic centre of South Africa?
Post by: Laban on April 08, 2012, 06:43:01 pm
Practicle Centroide S28 59' 37.8" E25 05' 15'2"
Title: Re: Where is the geographic centre of South Africa?
Post by: Laban on April 08, 2012, 06:54:13 pm
Laban's Centroide. Enigste plek met 'n PAW, kap 'n voorbriek, neem 'n potret, pak gou 'n paar klippe om dit behoorlik te merk, ok moet bieg Ja-ja het gehelp met die klippe pak!!
Title: Re: Where is the geographic centre of South Africa?
Post by: White Rhino on April 09, 2012, 04:47:28 am
:laughing4: very cool
Title: Re: Where is the geographic centre of South Africa?
Post by: shanks on May 20, 2013, 09:48:49 am


The guys who could calculate it electronically lost interest in this thread.

 :lamer:

Here you go...  ;D

PROVNAME   CentroidX                          CentroidY
Eastern Cape   26° 26' 46.898" E    32° 9' 14.499" S
Free State           26° 52' 2.150" E      28° 36' 51.852" S
Gauteng           28° 11' 51.183" E   26° 4' 31.572" S
KwaZulu-Natal   30° 44' 54.812" E   28° 42' 59.707" S
Mpumalanga   30° 17' 56.335" E   25° 52' 25.144" S
Northern Cape   21° 24' 10.114" E   29° 27' 12.258" S
Limpopo           29° 17' 23.148" E   23° 47' 7.207" S
North West   25° 32' 54.452" E   26° 16' 13.495" S
Western Cape   20° 36' 57.737" E   33° 0' 52.372" S
South Africa   25° 5' 38.087" E           28° 59' 43.146" S

That is 10 centroids to plot and visit then! Great stuff! :thumleft:
Had a chance to visit the centre of Limpopo over the weekend.
31 Km after leaving home I arrived!
1 down - 9 to go!
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on May 20, 2013, 09:51:20 am
Nice one Laban! Well done! :thumleft:
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on May 20, 2013, 10:26:44 am
 :thumleft: :thumleft:

Love it.
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 19, 2013, 10:58:10 am
According to the CIA the geograpic centre is 29 00 S, 24 00 E

Title: Re: Where is the geographic centre of South Africa?
Post by: Swart Gevaar on September 19, 2013, 11:12:31 am
 :sip:
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on September 19, 2013, 11:19:16 am
And the CIA is a world renowned source of truth and information.  :laughing4:
Title: Re: Where is the geographic centre of South Africa?
Post by: Fudmucker on September 20, 2013, 04:15:25 am
According to the CIA the geograpic centre is 29 00 S, 24 00 E

And the CIA is a world renowned source of truth and information.  :laughing4:

It's true if you ignore all the decimal points of the degrees.
I suppose that's accurate enough for the CIA.

Here we are arguing the devil in the detail of the decimal points...  :deal:
Title: Re: Where is the geographic centre of South Africa?
Post by: RobC on September 20, 2013, 08:29:26 am
Well I am off to find this one... :ricky:
Title: Re: Where is the geographic centre of South Africa?
Post by: Ratt on September 20, 2013, 10:36:03 am
Awesome, didnt even think of this. On my bucket list!
Title: Re: Where is the geographic centre of South Africa?
Post by: Heimer on March 24, 2015, 05:47:38 pm
Finally got the chance to visit the Western Cape practical Centroid on the way the the 2015 Western Cape bash

S33 04.572 E20 35.645
Title: Re: Where is the geographic centre of South Africa?
Post by: Laban on June 03, 2017, 04:21:12 am

...Op pad Riemvasmaak toe.... ;)
Title: Re: Where is the geographic centre of South Africa?
Post by: dax on June 03, 2017, 01:29:30 pm
Judging from your last photo, I'd hazard a guess and say that you shop at 4x4Direct!!!
Title: Re: Where is the geographic centre of South Africa?
Post by: sidetrack on June 03, 2017, 09:08:56 pm

...Op pad Riemvasmaak toe.... ;)
Oulike Schnauzer  :thumleft: Het self twee van hulle.
Title: Re: Where is the geographic centre of South Africa?
Post by: Pistonpete on June 04, 2017, 11:54:18 am
Finally got the chance to visit the Western Cape practical Centroid on the way the the 2015 Western Cape bash

S33 04.572 E20 35.645
Budda says....
Title: Re: Where is the geographic centre of South Africa?
Post by: Laban on June 06, 2017, 09:27:34 am
Judging from your last photo, I'd hazard a guess and say that you shop at 4x4Direct!!!

...Outdoor Warehouse Port Elizabeth .... :thumleft

:

...Op pad Riemvasmaak toe.... ;)
Oulike Schnauzer  :thumleft: Het self twee van hulle.

....