Finally get to pretend I am one of the cool kids - Holley kit swap

Dantra said

I don't know if you've seen them but dentists have the coolest scanners. I had to go last week for some dental stuff. I needed to get some impressions done because I'm at the time in my life that I need some partials. The dentist had this scanner that he drug around over my teeth and along my gums. Made perfect, in color scans of my teeth. I was dreading it because I thought it was going to be the old school way.. here, bite down on these gooey plates! He scanned upper and then lower.. had me bite down and then touched on each side off my teeth and the 2 images on the laptop just snapped together. Was pretty cool.

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I know exactly what you're talking about. I had that done as well because I got some aligners a while ago. I actually looked those up just for the fun of it to see how much they ran and the one that my dentist used at least was something like $5000 if I remember right. I believe that system actually uses photogrammetry, which is essentially taking a whole bunch of pictures and stitching them together. You can actually do the same thing with a regular camera and some free software out there (there are some tutorials on YouTube). I tried it once, but either didn't have enough pictures or didn't have a good enough setup or something. I'm guessing the dentist equipment is probably specifically built for that environment though, so likely calibrated to work on teeth best. I bet it would work well with small stuff though, like little switches and knobs and stuff that the larger scanners don't always place nice with.

Other systems use some variety of "structured light", which is just a fancy way of saying they project a pattern onto the object and measure the deformation in the pattern to work out the shape. Picture taking a projector and projecting something like stripes or a checkerboard onto something. You know it's supposed to be straight lines, but as it hits objects and different heights it's going to skew those to not be straight. You can do math to work backwards and figure out what caused the change in shape. What light they use exactly will vary from device to device. Some are visible like you can see like a regular project, some are infrared, some are laser, etc. You can kind of make your own system as well by just using one of those laser levels that projects a line and a camera with a turntable. Software is really what makes or breaks a system from what I've seen. I'm sure camera quality and what kind of light and pattern you use makes a difference as well, but in the end it's all about converting that data to a useful model.