[Proj] SPCS NC (3200) -> Lat Long Conversion Problem w/ Program

[Gerald Evenden]

Because I am not in any way involved with "pj_transformer" I cannot 
help you
with your problem.  However, if all you wish to do is transform NAD83 
North
Carolina coordinates to geographic coordinates, I think there is a far 
easier
way: libproj4.

Everything up to pj_init is the same but instead of using 
pj_transformer you
simply use pj_inv (inverse entry).  In addition, skip "parm_out" as it 
is not needed,
nor any of the pnt[XY] stuff.  Output of pj_inv is geographic 
coordinates in radians.

The following script does an example where the program "lproj" is a 
simple
application program that gives users access to the libproj4 library:

n83_3200="+proj=lcc  +a=6378137 +es=.0066943800229 \
+lon_0=-79 +lat_1=36d10 +lat_2=34d20 +lat_0=33d45 \
+x_0=609601.22 +y_0=0 +units=us-ft"
lproj $n83_3200 -f %.9f -I  <<EOF
2982350.290 849500.700
EOF

The results are:

-75.676777193   36.038892808

which match your Corpscon6 and cs2cs trials.

Entry pj_inv may still be left in the material you have and if it is, I 
suggest
you check it out.

As an editorial comment to the general audience, this is why I believe 
in
the separation of operations.  Kitchen sink procedures
cloud the issue for those seeking solution to simple processes.  Let 
different
functions do projection, datum shifts, XYZ transforms, etc.  Just make 
it
easy to assemble the set of building blocks needed.

On Apr 30, 2005, at 2:34 PM, Kevin S Lim wrote:

> Issue:  Output from my VC program does not match values from Corpscon6 
> or cs2cs.
>
> Input:  SPCS 3200 - North Carolina - 2982350.290 849500.700
>
> Proj4 Output (program): 75.764937678 33.842018951
>
> Corpscon6 and cs2cs output: 75.676777193 36.038892808
>
> Because the Corpscon6 and cs2cs output match, the problem likely lies 
> in my source code below:
>
> START OF CODE ***************************************
>
> void ReProjectPoints(FILE *ifp, FILE *ofp)
> {
> 	...


> _____________________________________
Jerry and the low riders: Daisy Mae and Joshua.
"The whole religious complexion of the modern world is due to the
absence from Jerusalem of a lunatic asylum." Havelock Ellis, 1914
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