sat_sim for inverse linescan mapprojection

[Matthew Hutton]

Hello,

I have a linescan ISIS cube image and corresponding CSM camera. I also have some map-projected data (ortho.tif, say) and I would like to "un-project" this data back into the camera so that I can use it to modify the ISIS cube. I thought I would be able to use sat_sim to do this as:

    sat_sim --dem dem.tif --ortho ortho.tif --camera-list camera_list.txt --sensor-type linescan -o run/run

The tool tells me I need to specify the --image-size and --velocity. I can figure out what the former should be from the cube, if needed, but I was expecting at least the latter to be read from the cameras.

Am I misunderstanding what this tool does? Is there a way to use this tool, or another provided by ASP, to perform this un-projection without modifying/generating a camera? (Similar to ISIS map2cam.)

Many thanks,

Matt

[Oleg Alexandrov]

The sat_sim tool is not strictly speaking meant for unprojecting an image. That said, I think it should work and I know of some people using it that way.

The image size parameter is needed because it needs to know how many samples to pick. (Some cameras store this image info, others don't.) Though only the speified width is used. The height (number of rows) is auto-computed based on the requirement that the pixels be square. (But this can be overridden.)

I don't think the velocity param is needed for this and when I get to it I will turn it off, as the velocity is needed to produce the camera, which you have. So you can set some velocity and hope it will go through the motions.

You can examine what you get and mapproject it back to see if it agrees with your original ortho. Hope it works.

In principle, one can also bake the CSM camera into the .cub and then use ISIS map2cam. 

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