I have a question about scan alignment (and comparison) with CAD model. CAD model which I have is specified positioned in 3D so I can accurately measure position of some points like holes or something else. Entire (real and computer) model consist of steel structure (which may be base for alignment) and foam parts (which are main elements for comparison). I doesn't want to use best fit method because on me case it may caused some discrepancies. So what should be best solution for this problem? I thought about two solutions:
Feature based alignment (and use for this aim some special geometric features on steel structure)
More difficult (but I think better) idea. Use during scanning special marker which will be used as coordinate system for scan (local CS), then I can check accurate position of three special points on CAD model (for example center of holes), and in last step I need to calculate what kind of transformation I need to perform on this local CS of scan to align those three points on scan to the same points on CAD model. After it I can import to some inspection software CAD model and 3D scan in the same coordinate system. I hope you understand what I mean.
But maybe there is any better idea to align those two models. If You have experience with 3D scanning and You can give me some tips for it I will be grateful.
Looks like you're needing to get into some more advanced reverse engineering workflow, same as us.
We've been using the XTract3D plugin with solidworks to build clean CAD models aligned and built around our 3D scan data. It's tough to explain, but it adds tools to solidworks that let you snap your curves and points to the 3D scan itself, and work from extracted cross sections of the scan as well. It can handle aligning coordinate systems to the data as well.
plugin: https://www.polyga.com/XTract3d/?ref=13&campaign=ML
They've got a bunch of training videos on their site that explain the process and show what the plugin can do. The video below is long, but it's a great resource on reverse engineering in solidworks, period. Taught me a lot.
https://www.polyga.com/video/xtract3d-advance-tutorial/