[Shapelib] General Shapefile questions

Frank Warmerdam fwarmerdam at gmail.com
Wed Jan 12 23:29:22 EST 2005

On Wed, 12 Jan 2005 13:50:06 -0700, Matthew Gardner <mattg at xlcable.com> wrote:
> It looks as though the shapefile C Library V1.2 can do this for us but I
> have some question.  Has anyone had any luck compiling or running this
> library on the Pocket PC?


I have successfully built and run shapelib on a
PocketPC (well in my case on the emulator).   I don't
recall the process being to complicated though there 
were a few minor hacks required.  I am not sure what
they were though.   Perhaps a few changes in the 
include files or IO stuff. The good news is that shapelib
is very simple low level code ... easy to port and tweak
as needed.

> Probably the bigger question is can we create a shapefile that could be
> imported onto many different maps?  I am new to GIS software and am
> unfamiliar with how all the data access works.  I have read through ESRI's
> technical description of shapfiles and it is very useful for learning how
> build a shapefile.  However, it doesn't explain how shapefiles interacts
> with other mapping software such as scaling issues or if it uses just
> latitude and longitude coordinates.

I'm not going to try and address broad issues of 
coordinate system or other use issues.  But if you 
produce Shapefiles in lat/long coordinates with 
the best accuracy you have available folks should be
able to get them to display in most modern GIS system.

Make sure you document clearly that they are in 
lat/long coordinates.  Ideally you would include a .prj
file with the datasets that declares them to be WGS84
(or some other appropriate coordinate system).  I can
provide the stock WGS84 .prj file if you can't find it
in your own ESRI software tree.  

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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