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hayes
Osiris (Active Member)
Joined: 03 Jan 2008
Posts: 8
Location: Caltech
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 Posted: Thu Feb 07, 2008 5:03 pm Post subject: Reading Vicar Image with Projection into ISIS |
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Hello,
I have a projected vicar Cassini ISS image that I would like to read into an ISIS 3 (or 2) cube and maintain the projection. VIC2ISIS does not seem to transfer the projection info along with it (doesn't read label). Is there a way to make a projected isis cube out of the vicar image.
I have also tried projected and reading the ISIS image in directly. Unfortunately, ISIS 3 does not project the ISS image correctly (puts known features in incorect places). The vicar projection does things correctly, but is limited to WEST longitude and not compatible with ARC GIS (also creates confusion in known bug which produces errors in sample and line offsets in .raw file).
Any help on reading the vicar projected cube in ISIS 3 while keeping the projection info would be much appreciated. Thanks! |
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thare
GIS Support Team
Joined: 22 Mar 2004
Posts: 657
Location: USGS Astrogeology Research Program, Flagstaff, AZ
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| Posted: Fri Feb 08, 2008 9:05 am Post subject: |
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If vicar2isis, either in ISIS2 or ISIS3, drops the projection then I think the only methods are (besides using vicar):
ISIS2: Read it in and then run lev2lab and type in the projection parameters. You will need to know a single control point to tell ISIS where the image starts in the given projected space.
ISIS3: Read it in and then wait for a yet to be released lev2lab-like program. This program is currently being written. I would think maybe in a few weeks or so we will be testing it (if it is not already done). I have been out of the office for a while so I haven't heard.
Postive East/West doesn't really come into play when using a map projection and your units are meters. Map projections really only work in positive East coords but planetary programs just remembers to report West. This is also true for the central meridian, if any. If the central meridian is tagged as west, the program will hide from you that it really plugs in pos. East values into the map projection. So, if you use vicar2world.pl to extract a worldfile and header for your image you can bring it into ArcMap. You should still define the projection for ArcMap (using post East values for the projection parameters). Once you do that, you should be able to easily reproject in ArcMap. You could do the same using gdalwarp (available in FWtools) although it took me a bit to figure out how to run gdalwarp (the trick is to define Well Known Text files for the current and output projections to give to the program).
good luck,
Trent |
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hayes
Osiris (Active Member)
Joined: 03 Jan 2008
Posts: 8
Location: Caltech
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| Posted: Fri Feb 08, 2008 11:56 am Post subject: Opening vicar projected cube in ISIS |
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Trent,
Thanks for the reply. I'd like to use the ISIS 2 solution so that I can get started. However, how do you read in a VICAR image into ISIS 2 using linux? According to a few web forums, ISIS2VICAR only works in the solaris version of ISIS 2???
I guess I can try converting the image to a 16 bit tiff after reading it into ISIS3 and then read the tiff into ISIS2 to give the projection information, but this sounds a little bit convoluted.
Thanks for any advice.
-Alex |
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thare
GIS Support Team
Joined: 22 Mar 2004
Posts: 657
Location: USGS Astrogeology Research Program, Flagstaff, AZ
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| Posted: Fri Feb 08, 2008 8:49 pm Post subject: |
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Stange I haven't heard that with vicar2isis on linux. Maybe they use the vicar code and had trouble with it on the linux side?
Anyway, Vicar files are normally just a raw files so maybe try this. run vicar2world.pl on the file using no options, "-e", or "-p". This will simply parse the label and write out an ASCII header. From one of the header types you can figure out the num line, samples, bit type and most important skipbytes. Now run raw2isis and use the skipbyte parameter to jump the header and read it as raw. Test the file in qview and then run lev2lab.
http://webgis.wr.usgs.gov/pigwad/tutorials/scripts/perl.htm
-Trent |
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