lcc tangent latitude

[buddy bajorin]

Greetings =)

Could someone please help with projection issues?

In trying to convert a raster image (gif) into a geotiff so that it can be reprojected into mercator. I'm very new at this so have attempted to read the docs carefully, but i have clearly made a mistake.

Since i'm new, and am using a linux box I have found that gdal seems to be the way to go, unless someone has a better suggestion (need command line for automation).

The projection information for the gif image is that it is a lambert conformal conic, but specifies a tangent latitude, instead of the normal 1 or two latitudes of natural origin. Here is the info and source information:

########## SOURCE PROJECTION INFORMATION ###################
## REF http://www.nws.noaa.gov/noaaport/html/icdtb48e.html #
############################################################
Eastern CONUS Lambert
Satellite: GOES East
Projection: Lambert Conformal
Tangent Latitude: 25.000N
Reference Longitude: 95.000W
Reference Grid: AWIPS Grid 211*
* The Dx, Dy grid increment (at 25 deg north) w as selected
so that the grid spacing would be exactly 80.0 00 k m at
35 deg north

Lower Left: 16.369N 113.133W
Lower Right: 14.335N 65.091W
Upper Right: 57.289N 49.385W
Upper Left: 59.844N 123.044W

1.0159Km @ 25.000N Visible
5120x5120
########################

so not knowing what I am doing, and googling for all that i can find I came up with the following means to set the projection, and reproject.

gdal_translate -of gtiff -a_srs '+proj=lcc +lat_ts=25 \
+lon_0=-95 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs' \
-a_ullr -123.044 59.844 -65.091 14.335 test.gif test.tif


I'm guessing the 'lat_ts' parameter is incorrect, i just happened to see it somewhere, but i have also tried setting the two lat parameters to 25 as well, which did not work. I also tried using default lcc projection information from ArcView for that projection to no avail.

Once finished my settings so far to convert to mercator are as follows
gdalwarp -t_srs '+proj=merc +a=6378137 \
 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 \
 +units=m +nadgrids=@null +no_defs' test.tif mercator.tif

I would really appreciate any help anyone can offer.. i've been banging my head off the wall trying to figure this out, it has sort of become a quest now... the issue seems to be using a tangent latitude instead of the 1 or 2 latitudes of origin.

thanks much,

--buddy

--

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