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DAVID-Laserscanner Forum • View topic - rough surface texture
Dear DAVID Community,

As you are probably aware, the entire DAVID company, team and product range has been integrated into HP Inc.
This forum is now read-only. Relevant content has been migrated to HP and merged into HP's Support Forums on November 1, 2016.

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rough surface texture

Questions, problems, comments and tips regarding the 3d scanning process.

rough surface texture

Postby jbeale » Mon Aug 13, 2007 6:56 pm

I tried out the scanner software for the first time last night. I used a cheap laser-leveller from Radio Shack with a beam about 2 mm wide, and it was much brighter at one end than the other. I mounted the laser on a video tripod head so I could scan it smoothly. This worked well, I was easily able to paint every pixel with a single pass. My camera was a Sony FX1 camcorder, which is HDV but I used the DV mode via firewire to my laptop. The camera was set to black and white mode and pseudo-progressive scan "cineframe mode". I had a completely dark room with the camera at +12 dB gain for consistent beam detection since my laser is not very bright.

My results show a bumpy "orange peel" type texture, which gets worse as the laser-camera angle is smaller. The target (ceramic face about 16 cm high) is much smoother than the scan appears.
Image
Image
Is my problem laser speckle and/or noise in the camera? Would I get better results with a brighter laser or more sensitive camera?

I wasn't able to get DAVID to read in the OBJ file without a camera connected, so the 3D screen grab is from another program "MeshLab".
Attachments
Scan2-Aug13-07.png
two scans at deep and shallow laser angle, showing rough texture
jbeale
 
Posts: 41
Joined: Sat Aug 11, 2007 9:20 pm

noise averaging possible?

Postby jbeale » Mon Aug 13, 2007 7:19 pm

It appears to me that the DAVID software calculates a single depth value per image pixel and once a pixel is "painted" that value stays, until you erase or reset the entire image.

Is there some way to turn on an "averaging" mode, so that a single pixel can be calculated as many times as it is illuminated, and then an average taken? Maybe even a weighted average since the software can form an error bound estimate based on frame-to-frame noise and camera-laser plane intersection angle. I believe this would give you a real improvement in the case of random noise. Low-noise cameras and powerful lasers are expensive, so I bet I'm not the only one with a noise problem.
jbeale
 
Posts: 41
Joined: Sat Aug 11, 2007 9:20 pm

Re: rough surface texture

Postby Simon » Mon Aug 13, 2007 8:36 pm

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Simon
DAVID Developer
 
Posts: 423
Joined: Sun Jan 21, 2007 3:40 pm
Location: Braunschweig - Germany

averaging strategy

Postby jbeale » Mon Aug 13, 2007 9:24 pm

Last edited by jbeale on Fri Aug 17, 2007 9:08 pm, edited 1 time in total.
jbeale
 
Posts: 41
Joined: Sat Aug 11, 2007 9:20 pm

next update?

Postby jbeale » Thu Aug 16, 2007 7:08 pm

jbeale
 
Posts: 41
Joined: Sat Aug 11, 2007 9:20 pm

Postby Simon » Fri Aug 17, 2007 8:11 pm

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Simon
DAVID Developer
 
Posts: 423
Joined: Sun Jan 21, 2007 3:40 pm
Location: Braunschweig - Germany


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