Adjusting registration via a ScanWorld's transform

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Josh_B
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Adjusting registration via a ScanWorld's transform

Post by Josh_B »

Is there an easy way to position scans in a registration by manually providing values for each ScanWorld's transform relative to the home ScanWorld?

I am trying to optimize a work flow for a project that had some awkward scans that often have very little overlap between them. In my normal workflow I register scans from a Leica P40 using only cloud constraints, and than if necessary place various patches for areas that didn't register well. On this particular project, it has been very difficult to get the height of the scans to register correctly so I started looking for alternatives. I'm not familiar with all of cyclone's features, but I noticed that I can view each scan's transform relative to the scan set as the home ScanWorld. I think it would be relatively easy to manually adjust these values once I've got all the scans close to registered using cloud constraints. My thought was that if I could create a second registration of the scans, but instead of using cloud constraints just plug in the values of the transforms from the first registration that got it close, I could then manually make incremental adjustments needed to get it just right.
jamesworrell
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Re: Adjusting registration via a ScanWorld's transform

Post by jamesworrell »

Would it not be easier to use vertexes created from features? You don't need much.

A typical method is to find an overlapping (ie in more than one scan) "corner" feature. Fence the corner, copy to new modelspace, then create three patches on each plane of the "corner", then create a vertex at the intersection of the planes and give it a registration label. Finally deselect all, select all point clouds, delete clouds, close modelspace - delete and merge.

Do the same thing in another scan at the same feature using the same patch sizes and locations. Typically concrete or other surfaces might deform right in the corner, or the corner can even be beveled and not exist, so intersecting planes can work quite well and can be surprisingly accurate.

Can also be a "point" feature too - the head of bolt perhaps if you are desperate .. depends naturally on what congruent features you have to play with.
Josh_B
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Re: Adjusting registration via a ScanWorld's transform

Post by Josh_B »

I believe the method you described is what I normally do when the cloud constraints don't get the registration tight enough. I usually can go through and add a few patches, vertices, or even cylinders on occasion to overlapping areas between scans and add these constraints to tighten things up. To do this I open a scan's modelspace, select the area of overlapping points I want to fit the object to, insert the object, label it (the same name across scans), and add the points back in. I think this is the same as you describe.

The difficulty with doing that on this project is that all of the geometry to assign object's like this to would be small items that take time to find in the scan, and I would need to find a lot of them (it's a scan of a building covered in wavy weatherproofing done while weaving through the maze of covered scaffolding surrounding it). When I view the interim results to check the accuracy of the registration, zooming in on certain areas makes it apparent that one scan is shifted slightly too high or low compared to the others. Thus, I was hoping there was a simple way to just shift "Scan X" up by "0.1 inches" but in a manner that wouldn't affect the behavior of the cloud constraints already in place.
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Re: Adjusting registration via a ScanWorld's transform

Post by jamesworrell »

How many scans?

Plan B - delete everything that can move from the control spaces - re-optimise constraints. So delete all of the wavy stuff. That scaffolding mesh can certainly make a mess of cloud to cloud - aside from obfuscating things, the movement can make a complete bollocks of things.
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Re: Adjusting registration via a ScanWorld's transform

Post by Josh_B »

I have 4 registrations each with around 50 scans. I can delete all the wavy stuff from the controlspaces, but I promise I'm not exaggerating when I say it would be over 90% of what is visible in the scan haha. Some 2x4's were placed over the wavy stuff randomly throughout to represent the face of things that were important, and aside from those almost everything else is irrelevant to what I need. However, occasionally there is something else solid enough to use (like the A/C units that the wavy stuff was cut around) that helps with elevation aspect of the registration. This may just be one of those scans that I'll have to take more time to get right, I was just really hoping for an easy way to incrementally adjust a single scan in a registration without affecting the cloud constraints already in place.
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