Best fit alignments

Can you pick and choose what points or surfaces from a point cloud are used for a best fit?

For instance in a casting application, if I am using the best fit alignment method, I really only want the featurs created by the pattern to dictate my best fit alignment, not features created by cores. This way it is easier to see if the cores are locating correctly.


Also, is it possible to only best fit something in only one direction? This doesn't come up very often, but I have had instances where I only wanted to allow a best fit in one direction and do not see where PC DMIS gives me this option.

Insert > PointCloud > Alignment = best fit for the entire pointcloud. That is, PCDMIS attempts to find a transformation that minimizes the deviation for all points. Sounds like this isn't what you want?

Two possible solutions come to mind:

1) hard probe features on the pattern, use a basic, iterative, or best-fit alignment to establish your coordinate system. Note that creating Points on this surface will be problematic -- PCDMIS applies probe compensation for points only in X+/X-/Y+/Y-/Z+/Z-. I doubt your points' surfaces point exactly in one of those six directions, so any point you create will have cosine error. BEWAREEEEEE.........

alternately

2) scan a COP. select, filter, + purge COP appropriately so only the pattern features are represented. build your pointcloud alignment from this COP, then hide it. Now create a 2nd COP and scan the entire part. Select, filter, purge, and colormap appropriately.

i like the 1st option because you would be aligning with the more accurate hard probe, but you would have to find some way to solve the probe compensation issue for points. It's do-able.

i like the 2nd option because it's easy. But less accurate.

Good luck!