On 11-03-29 12:22 PM, Dori wrote:
Hi,
I am trying to convert this GIF
https://picasaweb.google.com/izzybitsie/GDALImage?feat=directlink
<http://aviationweather.gov/data/products/swl/ll_12_0_cl_new.gif> to gtiff.
I used this command after assuming projection was lcc:
*gdal_translate -of GTiff -a_srs '+proj=lcc +lon_0=-95 +lat_0=25 lat_1=25'
-a_ullr $ulx $uly $lrx $lry ../maps/my_image.gif ../maps/my_image.tif *
If I try to view the image using ImageMagick I can see it but I get a warning
about TiffReadDirectory field tag 42112 encountered. If I try to view the same
image with a proprietary software then, I get the same warning but I am not
able to see the image.
...
Q1: is there any easy way to find out if this warning is caused because I am
using the wrong projection?
Dori,
Tag 42112 is a custom GDAL tag for storing metadata and is unrelated
to the projection.
Q2: Does the command I am using look OK?
The command looks plausible but from the output file it is clear
you are assigning corner coordinates that are lat/long, not LCC
projected meter coordinates. You will likely need to first reproject
the lat/long corners into projected coordinates before you can assign
them with -a_ullr. You could use the PROJ.4 cs2cs command or the
gdaltransform command to accomplish the reprojection from lat/long to
projected coordiantes.
Q3: How do I get rid of the warning to try viewing the image with the
proprietary software?
You can avoid the warning by using the commandline option:
-co PROFILE=GEOTIFF
This instructs GDAL to avoid adding any tags not in the GeoTIFF
standard. However, I suspect the warning isn't actually what is
interfering with use of the image.
Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, [email protected]
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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