A Simple Mirror Makes 3D Scanning More Efficient
This technique could speed up your 3D scanning workflow.
If you want to get a complete 3D scan of something, you need the scanner to “see” the object from every angle. Handheld scanners and turntables both help in that regard, but unless you’re hanging the object from a thread, there will always be an area the scanner can’t see — usually the surface it rests on. That means you have to reorient the object at least once to scan the entire thing. But it turns out that you can avoid that by simply putting a mirror under the object.
Thomas_openscan posted this idea and his testing to the r/OpenScan subreddit and admitted that he wasn’t sure if it “is a stupid or good idea.” Personally, I think it is pretty clever.
For the test, he used a DIY OpenScan Mini 3D Scanner. He then placed a round mirror on the rotating pedestal and performed a scan.
3D scanners are optical (though some operate outside of the visible light spectrum) and so they can also scan whatever the mirror reflects. In this case, that is the bottom of the object resting on the mirror. The resulting point cloud (and then the 3D mesh) therefore contains both the “actual” object and its mirror image.
Joining the two together is quite simple, as 3D scanning software is built to perform that kind of work. Just separate the two halves, mirror one across the mirror plane, and then align the two. Mesh that and you get a complete model, without any physical repositioning necessary.
This should work with most (maybe all?) 3D scanners, as long as the mirror view and range are appropriate.
The big question is if the process is worthwhile and I think the answer to that will depend on your workflow. You have to decide which takes more work: repositioning and rescanning, or processing the mirrored scan.
In favor of the mirror approach, consider that you won’t get table geometry in the scan (which has to be removed), because the 3D scanner only “sees” the object, its reflection, and the rest of the room (which should be too distant to register). It would also be useful for objects that only have one stable resting position.
So, the next time you’re doing some 3D scanning, try it with a mirror!