Coordinate Transformations

Topics: SharpMap Project, General Topics
Feb 11, 2007 at 10:06 PM
Dear All,

SharpMap is well on it's way supporting all kind of different projections; however, as I wanted to transform coordinates from a "Double_Stereographic" projection to WGS84, I found out this projection has not been implemented so far.

Is there anybody who made some start already? I wish to, however I have no clue yet what the algoritm would look like...

I need it in order to translate the local Dutch Coodinate System (Rijksdriehoekstelsel) to lat/lon...

Any suggestions?

CoCalc
Feb 27, 2007 at 2:27 PM
I too am looking for a DoubleStereographic projection algorithm. I have tried other libraries and have found the standard "Stereographic" projection, when properly configured seems to be the same as the DoubleStereographic (or at least very close). Let me know if you have tried this and what your findings have been so far!
Mar 8, 2007 at 6:18 PM
Just to follow up, I did some reading and MANY different sites and books and found out that the double stereographic projection is actually identical to the Oblique Stereographic (EPSG) projection. See the site at http://www.remotesensing.org/geotiff/projlist/obliquestereographic.html for details.
Coordinator
Mar 9, 2007 at 8:13 PM
Great find -

Below is another resource for learning about projections. It is a book from the USGS called "Map projections; a working manual". It is a DjVu file, so you need an appropriate reader - for which the LizardTech viewer serves nicely.

http://onlinepubs.er.usgs.gov/djvu/PP/pp_1395.djvu
Mar 10, 2007 at 6:20 PM
Thanks. It took A LOT of digging and reading to find the information. I had already found the projections working manual you were mentioning but thanks anyway. It seems quite complete. Also, the LizardTech viewer is browser based unless you pay for the stand alone viewer. I prefer the open source WinDjVu viewer which is stand alone and free. Here is the link in case you would like it: http://sourceforge.net/projects/windjview.
Mar 18, 2007 at 8:53 AM
I think it will be easiest to just port parts of the PROJ.4 toolkit (http://proj.maptools.org/) to the .NET platform...
Coordinator
Mar 26, 2007 at 9:17 PM
Edited Mar 26, 2007 at 9:17 PM
But, where's the fun in that? ;)
Coordinator
Mar 26, 2007 at 9:19 PM
BTW - I can open DjVu files on my filesystem when only the LizardTech viewer is installed... it runs in it's own frame, too, not just a browser.