[Proj] Two questions about Proj

Andy Canfield andy.canfield at gmail.com
Fri Jan 20 11:17:27 EST 2006

Actually I was meaning something different in my questions because I
didn't realize most folks use Proj4 from the command line. What I was
really meaning was how do I find an example of using it from C or C++
as a dynamic library or compiled source into my project? I need to
translate coordinates from Lat Lon NAD 83 to State Plan and Vice Versa
and I would rather not have to write it if Proj4 already supports
doing it.

The V&H question was because I used to work for AT&T and I still work
for the same company but our portion of AT&T was bought by another
company. If V&H wasn't supported by Proj4 I would be willing to add it
once I get familiar with the source and how to use it I could add that
and submit it. It's just I'm not familiar enough with Proj4 to know
how it would be used yet. I have written the code to translate Lat lon
to V&H and vice versa in Java and in C++ for two different projects
where I work so translating it into C or whatever Proj4 is written in
should be fairly straight forward. I'd like to get the translation out
in public and open source since it seems to be such a hard projection
to find tools for and the tools that do exist cost way to much for
what they do. Also I think it would go well with the Open Source
spirit that AT&T of old had with it's Bell Labs projects and all the
things it contributed to computing in general.

Oscar is correct we still use V&H to calculate distances between rate
centers for billing purposes on calls.


On 1/20/06, Frank Warmerdam <warmerdam at pobox.com> wrote:
> On 1/19/06, Andy Canfield <andy.canfield at gmail.com> wrote:
> > First question:
> > Is there a good example somewhere of using it to transform coordinates
> > from one projection to another?
> Andy,
> I'm not sure what qualifies as a *good* example.  A simple example
> might be:
> cs2cs +proj=utm +zone=11 +datum=WGS84 +to +proj +zone=12 +datum=WGS84
> > Second question:
> > Is there a good example somewhere of using it to shift from one datum
> > to another within the same projection?
> cs2cs +proj=utm +zone=11 +datum=NAD27 +to +proj=utm +zone=11 +datum=NAD83
> > Third question:
> > Does it support translating coordinates to and from the old AT&T V&H
> > coordinate system?
> This is not supported by PROJ.  I see Oscar has provided excellent
> details on how you could accomplish it.
> 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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