[Gdal-dev] GDALWARP / GDAL_TRANSLATE / ECW Questions

[Lowther, David W]

Howdy,

Since I may be approaching my task in the wrong way, let me let you all know
what I am trying to do...

My desired result is a set of ECW formatted image files for use in mapserver
in the following projection:

	proj=aea
	lat_1=29.500000000 #SP1
	lat_2=45.500000000 #SP2
	lat_0=23.000000000 #REF LAT
	lon_0=-96.000000000 #CENTRAL MERIDIAN
	x_0=0.000 #FALSE EAST
	y_0=0.000 # FALSE NORTH
	datum=NAD83
	ellps=GRS80
	no_defs

I have 2 options for input files. 

The first option is .bil files with .hdr's in the following projection:
	proj=utm
	ellps=GRS80
	zone=14 (or 13 or 15)
  	north
	no_defs

The second option is .tif files with .tfw's already projected like my
desired output.

I have no trouble using gdal_translate to convert from either .tif or .bil
to .ecw.

The problem that I have is that the images projected in Albers have black
around parts of the edges. As I intend to display them side by side in
Mapserver I need to use the OFFSITE argument to hide this black. When the
images are in .tif format this works fine, but once they are .ecw only part
of the outside is masked - I'm guessing because the black is not all
completely black after conversion to .ecw.

Is there a way to handle this?


Also, when I use gdalwarp to project to Gtiff with the -co "TFW=YES" option
no TFW is created.

Example:
E:\IMAGES\DataIn>gdalwarp -s_srs .\utm14.proj4 -t_srs .\albok.proj4 -of
GTiff -co "TFW=YES" 34097h21.bil e:\images\dataout\34097h21.tif
Creating output file is that 6626P x 7890L.
:0...10...20...30...40...50...60...70...80...90...100 - done.


I am using the gdal_translate and gdalwarp on Win2K - build 1.1.8.


Thanks for all your help and sorry if this is rambling or confusing...

David Lowther
Software Engineer
GEO Information Systems
University of Oklahoma
dlowther at ou.edu
(405) 325-3131
http://www.geo.ou.edu <http://www.geo.ou.edu> 



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