[gdal-dev] Satellite projections

[Simon Richard Proud]

Oops, sorry! I forgot to include the -a_ullr variables. I have:
up_left_x=-5570248.832537
up_left_y=5570244.832537
low_rig_x=5567248.429179
low_rig_y=-5567252.429179

That should cover the full disk and seems to work with all satellites - you just need to vary the longitude to change between GOES/MSG/MTSAT etc.
Cheers,
Simon

________________________________
Fra: Jerl Simpson [jsimpson at wxtrends.com]
Sendt: 28. oktober 2013 16:41
Til: Simon Richard Proud
Cc: gdal-dev at lists.osgeo.org
Emne: Re: [gdal-dev] Satellite projections

Thanks Simon!

I'll give it a shot.  Meteosat is definitely a pain, and it's one of the satellites I'm working with.

If you don't mind me asking, what do you typically have in your -a_ullr designation for gdal_translate?  Or are you pulling out sections and it varies?  I'd like to get the full image, if possible.

Thanks again!

Jerl


On Mon, Oct 28, 2013 at 10:33 AM, Simon Richard Proud <srp at geo.ku.dk<mailto:srp at geo.ku.dk>> wrote:
Hi Jerl,
We work with Meteosat data in full disk projection and it's a bit of a headache! Try these commands in GDAL and see if they work for you:

gdal_translate -a_srs  "+proj=geos +a=6378169 +b=6356583.8 +lon_0=9.49 +h=35785831" -a_ullr $up_left_x $up_left_y $low_rig_x $low_rig_y $INFILE $TEMPFILE
gdalwarp -s_srs '+proj=geos +lon_0=9.49 +h=35785831 +x_0=0.0' -t_srs '+proj=latlong +datum=WGS84' -tr 0.01 0.01 -te 0 20  70 70 -order 3 $TEMPFILE $OUTFILE

Just remember to change the +lon_0 to whatever you need for GOES. Also change the -tr and -te for gdal :-) You can also add +lat_0 but to be honest I never found it made a difference (perhaps it is ignored?)

Cheers,
Simon

________________________________
Fra: gdal-dev-bounces at lists.osgeo.org<mailto:gdal-dev-bounces at lists.osgeo.org> [gdal-dev-bounces at lists.osgeo.org<mailto:gdal-dev-bounces at lists.osgeo.org>] på vegne af Jerl Simpson [jsimpson at wxtrends.com<mailto:jsimpson at wxtrends.com>]
Sendt: 28. oktober 2013 16:17
Til: gdal-dev at lists.osgeo.org<mailto:gdal-dev at lists.osgeo.org>
Emne: [gdal-dev] Satellite projections

Hi guys:

I have a few data sets that come from the GOES satellites (Full Disk) and a couple others.  I can use one of the SSEC's programs to convert from their format to a netCDF.  No useful SRS info comes along in the conversion.

I've applied an SRS to them using gdal_translate and PROJ.4 that looks like:

"+proj=ortho +lon_0=-79.8 +lat_0=.208"  (lon/lat is the position of one of the satellites)

(I've also tried):
+proj=ortho +datum=WGS84 +ellps=WGS84 +lon_0=-79.8 +lat_0=.208

I'm wanting to get them into EPSG:4326.  When I do this, I end up with corner coordinates of a very small area just below the satellites position.

Does anyone have an suggestions that might help me warp this into position?  I'm sure there's something obvious that I'm missing.
I found this page, and the copied/pasted bit about the projection, but my attempts have not been successful.

http://www.gdal.org/frmt_msg.html
Georeference and Projection

The images are using the Geostationary Satellite View projection. Most GIS packages don't recognize this projection (we only know of ILWIS that does have this projection), but gdalwarp.exe can be used to re-project the images.

Thanks!




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Jerl Simpson

Sr. Systems Engineer

Weather Trends International

jsimpson at wxtrends.com<mailto:jsimpson at wxtrends.com>

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