[Proj] SP1 question
Gerald I. Evenden
geraldi.evenden at gmail.com
Wed Nov 22 13:34:53 EST 2006
On Wednesday 22 November 2006 12:32 pm, Jamon Van Den Hoek wrote:
> hi all,
> i'm having trouble achieving a transformation from a point's lat/long
> coords into a user-defined projection with one standard parallel.
> i'm using PROJ.4's 1SP LCC function (at
>html) with the following projection parameters:
> 1. Origin Longitude (£fo): 90¢X00¡¦00.000000¡¨
> 2. Origin Latitude (£Xo): 43¢X22¡¦00.000000¡¨
> 3. False Easting (Eo): 147218.6942 meters (482999.999 U.S. survey feet)
> 4. False Northing (No): 0.0037 meters (0.012 U.S. survey feet)
> 5. Scale Factor on Central Meridian (ko): 1.0000365285
> and the following code:
> C:\>proj.exe -I +proj=lcc +lat_1=43d22'0"N +lon_0=90d00'0"W
> +k_0=1.0000365285 +x_0=147218.6942 +y_0=0.0037 +ellps=GRS80 44d10'00"N
> 89d48'00"W (lat/long of point i want
> to transform) 131d4'1.401"E 89d59'59.907"S'00"N 89d48'00"W (not sure
> how to interpret this output line)
> 1d48'57.388"W 43d21'8.09"N (if "enter" is
> pressed again, this it outputted)
The main thing wrong is that you seem to want a forward projection yet set
the -I option to compute the inverse projection. This explains why you get
geographic coordinates as output.
I constructed the following script:
lproj +proj=lcc +lat_1=43d22n +lon_0=90dw +k_0=1.0000365285 \
+x_0=147218.6942 +y_0=0.0037 +ellps=GRS80 <<EOF
and got the following answer:
Also note that longitude precedes the latitude on input.
Another note: it is unusual to use a k_0 factor greater than 1. A more
typical value would be 0.999 and the value depends of the latitude range of
your projected area.
> i'm not sure where the error is coming into play that's producing this
> garbage. i want answers in meters, but i'm still getting dms. - the example
> PROJ.4 commands from the readme.txt work fine and i replicate the answers,
> so i know that PROJ.4 is installed correctly. - i changed the format of the
> lat_0 and lon_0 parameters in terms of using "-" instead of W, etc., and
> changed the order of input for the lat and long coords for the county
> point. - i also tried to replicate the example parameters at
>html but couldn't replicate the results.
> any suggestions as to how to fix this problem? is my syntax incorrect or is
> something missing from the command?
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist
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