Realignment of projected images

I have a number of large, complicated Galileo SSI mosaics that I spent a number months putting together. I did a lot of work making sure all the image overlaps had pixel per pixel perfect alignment. A huge amount of work was also put into getting the brightness and contrast of images matched up, as well flattening out the lighting using photometric correction.

So, the original plan was for the people I’m working with to import these into ArcGis, and then the lat/lon information was going to be wiped and redone in ArcMap. Since the final camera pointing in the Isis image wasn’t going to be of any concern, I didn’t try to get the final mosaics closely pinned to the basemap. They were unable to get the realignment working in ArcMap, so this plan is being scrapped.

I’ve found that trying to include the basemap in control networks creates a huge jump in the degree of difficulty. I’ve also found having any held images in the control networks makes it much more difficult to get a good solve in jigsaw. Overall, Galileo SSI images can get extremely finicky with alignment. I often have images that go through the whole qnet/jigsaw process just fine, but refuse to align once projected. I frequently have to leave certain problem images out, and then do special alignment with qtie or any other trick I can come up with.

Another problem I’ve run into, is that I’m finding a lot of misalignments in the basemap. I attached a gif of an area that has this problem. Because of this, getting everything exactly tied to the basemap along with having the image overlaps perfectly aligned is not really possible.

So far I’ve found no way to change the pointing on anything that’s been map projected. If there was way to adjust the pointing on the finished mosaics, and get them closer to the basemap, it would save me months of work. Some of these have drifted off from the basemap by a kilometer or two in the alignment process. Looking at my working directories, all the images were projected about a third of the way through the whole process. It’s looking like I’ll have to scrap pretty much everything, and start from the ground up.

If there are any workarounds to this problem, it would be a huge help.


Unfortunately projecting data is not a reversible step in ISIS. once you’ve projected the data there are ways to re-interpolate the data and change the projection or projection parameters but this doesn’t change the spatial alignment of the projected data.

So, you will need to work with correcting the un-projected imagery and then reprojecting it.

If you absolutely must, you can try using the map2cam application to “undo” the projection, but it requires input imagery to project back into.

I guess I have my work cut out for me. I try to keep my mosaics in a camera projection for as long as possible while I’m still doing alignment work. Hopefully these will work out as a starting point.

The only way I can come up with for making these sort of adjustments with projected images, is to used coreg. If coreg doesn’t cut it, then I’ll hand edit the control network produced by coreg, and then use it with warp.