| 13 Oct 2009 05:56 AM |
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Hi
I am testing the DEM extraction modules with a set of GeoEye-1 stereo images, but have a problem:
To create an exact DEM one needs to utilize the RPC (rational polygon cooeficient) information, which comes with the images in two separate files. But how to do this when the DEM wizard does not ask you for the RPC information?
I also tried to associate the RPC to the images prior to starting the DEM extraction, but this gives another problem as the program is now not able to calculate the Parallax; you just get the message: "Maximum Y Parallax: NaN".
Please can someone help?
Eva
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| 13 Oct 2009 08:26 AM |
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Are you opening the GeoEye data in ENVI with one of the options under File > Open External File > GeoEye-1? If so, and if your RPC data is in the standard RPC files that usually come with GeoEye data, then ENVI should automatically be able to find those RPCs when you go to do the DEM Extraction. You shouldn't need to later associate the RPC files with your opened images.
When you open the files that way prior to starting the DEM Extraction, do you run into trouble?
Peg
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| 14 Oct 2009 12:55 AM |
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Peg - thanks for your reply.
I think this is in fact the same as I did when I associated the images with the RPC information, which I did through the file header. (NB: be ware og the program falsely defining the coordinate system - you need to change it back).
Anyway, since yesterday I have found out, that the DEM module doesn't run properly on a 64 bit computer. It seems that some essential functions in the Wizard fall out, like the one where you are supposed to point to the location of the image RPC's.
Eva
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| 14 Oct 2009 12:41 PM |
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I don't really follow what you are doing and what is happening. You should not need to associate the RPC information with the images if ENVI knows that they are GeoEye-1 data. But it is also true that if ENVI does not know the sensor, and so does not know how to identify the RPCs, then after you identify the left and right images, the DEM Extraction wizard should prompt you to navigate to the RPC files.
I don't see any previous reports of problems with the DEM Extraction wizard that are specific to 64-bit systems. So, the problem that you mention here is apparently no known to ITT VIS. If you have run into one, would you please report it to ITT VIS technical support at support@ittvis.com or (303) 413-3920? That way they can investigate it, and log the bug for the developers to fix.
Peg
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| 15 Oct 2009 06:44 AM |
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Hi Peg
I have actually had some other strange problems with the DEM module on my 64 bit PC, which I didn't have on my 32 bit PC, but I suppose it can due to many other things as the mashines are of course not clones of each other. Sorry for all the fuzz. - i'ts probably nothing..
Eva
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