Coreg alternatives

I’m working with Voyager images of Callisto, and I’ve been struggling through the alignment process. I’ve been trying to get perfect alignment with the basemap, but I’m ending up with all these small sections that veer off by a few pixels. I’ve haven’t had this happen with Galileo or Cassini images. I’ve been through a lot experimentation with qnet/jigsaw and automated control networks without any improvements.

Here’s visual of the situation:
You can see the type of warping I’m taking about toward the lower right hand corner.

So, my next course of action was to use coreg to try to push these warped areas back into place. Under the right circumstances, this command has been able to make magic happen with imperfect alignments. After many tries, I’m finding that it’s just not cutting it with this group of images.

I was wondering if there is a command out there that does same sort of thing as coreg, but I can feed it a separate hand edited control network grid and it will warp the image to fit it; Or if there’s a way to hack the coreg command to get it to do this. If so, it will save me from this situation. I’ve been hammering away at this for months.

Hi @mvalenti-seti, there is a program called warp that may do what you want. It takes an image and a control network for it as input. You’ll have to read the description to make sure the network has what it expects. Worth a shot.

I’m sorry building a standard network and bundling is not working out for you. It’s pretty hard to nail down some features when the only overlap offered is high emission smear.


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I was moved to working on Galileo NIMS images for the last few months, and I’m now starting to get to back to this.

I went through a lot of trial and error the warp command. I made the control network with coreg, edited it in qnet, and then used warp to apply the changes. The results I’m getting are like variations of the gif I posted above. Its looks like each individual point is not getting warped enough to match up with the area I want it to. If I go in and over shoot the point in the direction I want it to go it by a few pixels, it gets closer to where I want it.

I’m not totally clear on all the parameters for warp. It seems the weighted parameter might help. I tried but I didn’t see a lot of difference. If I give it a number over 3, it crashes.

Any input would be appreciated.

I don’t have much more to offer @mvalenti-seti. The last time I ran warp was nearly 20 years ago and I’m sure a lot has changed since then. I was warping an old scanned paper geologic map of Ganymede to the new USGS digital basemap and I recall needing a lot of points. I can’t recall how that all worked out in the end.

I have also found that with control networks, putting points precisely where they are needed to seemingly tack something down does not always work, especially if those points are left FREE. The entire image is going to adjust based on the output of the bundle and may pull features away from their intended location. You can always change those points from FREE to FIXED, but that can really jack up the errors in the end. But if you already have a network that’s something to try (you could either use cneteditor to change PointType from FREE to FIXED or convert to PVL and edit the net).