Grainy Scan troubleshooting

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3dxcan
Posts: 74
Joined: 02 Jun 2017, 17:21

Grainy Scan troubleshooting

Post by 3dxcan »

Hello everybody,
I've built my David SLS using custom hardware, IS DMK23U236 Camera, Computar 12mm lens, ACER P1283i projector, I could almost eliminated waves and lines in scan, using recommended procedure to sync projector and camera refresh rates, however I'm faced with scans with grainy surface quality, as an example, please check the quality of the shampoo bottle scan, the part is molded plastic but the surface quality is similar to cast iron with grainy finish in David and Geomagic viewer. I Know I can post process the stl to get smoother results, but I'm looking for ways to eliminate the grainy finish in scan mode. I'd appreciate your comments.
scan.jpg
Curiousjeff
Posts: 121
Joined: 16 Nov 2016, 22:31

Re: Grainy Scan troubleshooting

Post by Curiousjeff »

1) Proceeded to fusion. This step often blends and removes some surface artifacts. Try different resolutions.

2) What happens when using the same setup on a very mat surface. Plastic can be shiny, which also induces surface artifacts.

3) Reduce brightness of projector a bit

4) Use optimal f-stop

Must other things but this list is what first comes to my mind.

Jeff
3dxcan
Posts: 74
Joined: 02 Jun 2017, 17:21

Re: Grainy Scan troubleshooting

Post by 3dxcan »

Jeff, thanks for your help, I could open up the lens diaphragm and instead tweak camera gain to get a well lit but not overexposed image and get smoother surface finish in my test scan. please let me know if that's a good option to tweak camera gain?
i believe the culprit was that diaphragm was too close to compensate for the bright picture of the projector. does anyone here also modifies gain?
Oteck
Posts: 82
Joined: 11 Nov 2016, 21:21

Re: Grainy Scan troubleshooting

Post by Oteck »

by diaphragm you mean the aperture. you only need to close that to a point thats enough to put all your subject in the Depth of feild; anything outside that will be blurry and unusable. I would not touch any of those gain or any built in camera setting unless it's the color format (don't use mjpeg or any compression) and turn off auto exposure if there is a setting.

Also suggested to turn off any light in the room to get the most of your projector. I"ve scanned matt black objects this way and it does not require it to go full brightness
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