[Proj] Proj API feature requests
judd at seas.marine.usf.edu
Thu Apr 22 13:16:18 EDT 2004
I've been using the proj library through the C API for a couple of years
now. Although I like the simplicity of the API, a couple of extensions would
be useful to make some of the command line tool's functionality available in
C code without having to parse the command line tool's output.
Here's a list of what features would have made my life easier in the
past, and a couple of things that would make things easy enough that I could
add more functionality to my programs:
1. Verbose configuraion information, similar to cmdline's '-v' (to be
used to generate FGDC compliant metadata).
2. Per-point characteristics, similar to cmdline's '-V'
3. Error estimation similar to cmdline's '-S' option.
4. Querying through the API of available projections and their
information, as well cartesian units querying, similar to the cmdline's
'-l', '-lP', '-lu', and '-le' options.
Returning strings would work in a pinch, but it would be nice to get
direct access to the data structures that hold this information. After a
quick look at projects.h, it looks like the interesting structs are going to
be: PJ_LIST, PJ_ELLPS, PJ_UNITS, PJ_DATUMS, PJ_ELLPS, PJ_UNITS,
PJ_PRIME_MERIDIANS, FACTORS. Of course, direct access to the structs via the
API makes might break backwards-compatibility if they change down the
road... so maybe something else may work better.
For #2-3 above, a seperate function for pj_fwd(), pj_inv(), etc... would
be nice as the extended information would be available, but if you don't
want it you could just call the normal functions which should be faster.
Computer Research Specialist
Institute for Marine Remote Sensing
University of South Florida
140 7th Ave. South
St Petersburg, FL 33701
(727) 553-1103 (fax)
judd at marine.usf.edu
More information about the Proj