[OSRS-PROJ] The "almost" Lamber Conformal Conic Projection
Gerald I. Evenden
gerald.evenden at verizon.net
Mon Mar 3 19:40:15 PST 2003
Very interesting. The results at this end from the script are:
[gie at localhost src]$ ./lcca
forward projection of:
34d08'11.291 37d31'17.625
15707.96 623165.96
EPSG guide 7, pdf p. 22 gives values of: 15707.96 623165.96
inverse check of forward
34d08'11.29100"E 37d31'17.62500"N
[gie at localhost src]$
Ahhhhhh---I see it. PUT "no_defs" in the script. "Spec'd but
not used". <<------------------------
I will correct the lcca.txt script.
Your local datum overrode the +b facor. Look carefully at the
beginning of the -V output.
As you will note, my machine matches exactly to the cm.
On Mon, 2003-03-03 at 21:54, Frank Warmerdam wrote:
> Gerald I. Evenden wrote:
> > The almost Lambert Conformal Projection, +proj=lcca, source code,
> > test script and documentation are available at:
> >
> > http://members.bellatlantic.net/~vze2hc4d/proj4/
> >
> > The procedure only services the truncated series form of LCC to
> > satisfy conversions of some French, North African and near Eastern
> > interests. It has only been tested for the northern hemisphere but
> > if anyone knows of any usage in the southern hemisphere, let me
> > know.
> >
> > Please DO NOT use this projection for new applications. It is
> > only for handling existing usage.
> >
> > Please let me know of any problems or have any suggestions.
>
> Gerald,
>
> I am incorporating the lcca into the remotesensing.org version of PROJ.4
> but when I run the test script I don't get a close match to the EPSG values
> you list. Should I?
>
> warmerda at gdal2200[60]% sh ~/lcca.tst
> forward projection of:
>
> 34d08'11.291 37d31'17.625
> 15713.70 623182.75
> EPSG guide 7, pdf p. 22 gives values of: 15707.96 623165.96
>
> inverse check of forward
>
> 34d08'11.29100"E 37d31'17.62500"N
>
>
> If I run the first step of the test script with -V I get:
>
> warmerda at gdal2200[162]% ./proj temp -V +proj=lcca +a=6378249.2 +b=6356515.0 +nea
> rly +lon_0=37d21 +lat_0=34d39 +k_0=0.99962560 +x_0=300000 +y_0=300000
> #Lambert Conformal Conic Alternative
> # Conic, Sph&Ell
> # lat_0=
> # +proj=lcca +a=6378249.2 +lon_0=37d21 +lat_0=34d39 +k_0=0.99962560
> # +x_0=300000 +y_0=300000 +ellps=WGS84
> #--- following specified but NOT used
> # +b=6356515.0 +nearly
> #Final Earth figure: ellipsoid
> # Major axis (a): 6378249.200
> # 1/flattening: 298.257224
> # squared eccentricity: 0.006694379990
> Longitude: 34d8'11.291"E [ 34.136469722 ]
> Latitude: 37d31'17.625"N [ 37.5215625 ]
> Easting (x): 15713.70
> Northing (y): 623182.75
> Meridian scale (h) : 1.00087594 ( 0.08759 % error )
> Parallel scale (k) : 1.00089192 ( 0.08919 % error )
> Areal scale (s): 1.00176864 ( 0.1769 % error )
> Angular distortion (w): 0.001
> Meridian/Parallel angle: 90.00000
> Convergence : -1d49'37.527" [ -1.82709072 ]
> Max-min (Tissot axis a-b) scale error: 1.00089 1.00088
>
> 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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