I share your frustration regarding the cause of the waves/strips in the scans.
I also want to try different hardware adjustments, but I thought it was a good idea to study the images that David is capturing and try to identify the problem before.
I setup the folder: SL-TestSequence
TEST 1: All images from a single vertical scan (27 images) of a newspaper without the light of the projector touching the paper.
1) After calibration, I scanned a flat page with printed text. The projector is prevented from lighting the paper (but it is ON, with fan turning). In this case, all images should be the same without any projector illumination. I then loaded all the images into Photoshop, placed them one on top of another to see if there was any shaking / misalignment but this did not seem to be the case. There were differences, but they seem to be frequency/shutter related. Some images were brighter then others.
TEST 2: All images from a single vertical scan (27 images) of a newspaper with the same pattern projected on all 27 images.
2) I scanned a flat page with printed text. The projector is ON but it is projecting a single pattern (in David, I switch the projector screen to 1 and loaded a pattern as my Windows desktop background). In this case, all scan images will be photos of the same paper with the same illumination. I then loaded all the images into Photoshop, placed them one on top of another to see if there was any shaking / misalignment but this did not seem to be the case. Same as previous test.
But the actual scan of a 3D items does have strips ?
I am not sure now that the fan is the culprit ?
I did notice something else unusual. I scanned twice the same item with the same settings and miracle..the second scan was much better.
I am puzzled.
If the cause was some vibrations, I imagine that it would not be too difficult for David to realign the images before the "interpretation process", for example by placing in all the patterns a crosshair and placing a physical marker in the scene at the same place as the projection crosshair. This would allow correction of camera and/or projector shaking.
If the cause is shutter/frequency, I imagine some algorithm should be able to deal with it prior to processing (?)
Last solution, a specific algorithm in David only to deal with strips but without softening the rest of the texture.
I would love to see a series of photos that give a nearly perfect scan.
Panasonic GH4 4K with lens 12-35, Inogeni 4K to USB3 hdmi capture device, projectors: Acer K135/Acer K11/NEC V260X, Canon 60D, macro 60 mm, MagicLantern