[Proj] Intro and new Excel wrapper for proj.4

John Buonagurio jbuonagurio at exponent.com
Wed Sep 21 14:18:22 EST 2016

Hi all, 

I'm new to the list. I just finished an Excel API wrapper for 
pj_transform(), which was surprisingly straightforward thanks to the 
easy build with NMAKE and simple API (I can't say enough good things 
about this library). Here's the GitHub page with some basic 


I started this a couple years ago actually, but just recently changed it 
to use the native Excel C API and added some other improvements like the 
EPSG() function to return proj.4 strings from a giant switch statement 
(for single file deployment / separate folder and PROJ_LIB not 

I have a few improvements planned, but please let me know if you have 
any suggestions or feedback: 

- create an installer and chm help file
- test against GIGS
- use pj_is_latlong() so you don't have to use radians 


On a somewhat unrelated note, I also started working on a library 
version of NGS HTDP, and a simple wrapper to use it in R: 


The library isn't quite ready for prime time just yet - need to make a 
proper C binding with iso_c_binding (only works with GCC at the moment), 
add the required explicit interfaces and other cleanup. At this point 
the F77 code is mostly unmodified. 

I know you have the crs2crs2grid.py utility to generate HTDP grids 
between specific epochs, but I think it would be cool to embed HTDP in 
such a way that you can provide epoch dates as parameters in the proj.4 
string. Would probably take quite a bit of work to do this 'cleanly' 

Thanks for the great software, 

John Buonagurio 

More information about the Proj mailing list