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why still use a 90deg corner for calibration for SLS?

Discussions about latest DAVID developments, beta versions...

why still use a 90deg corner for calibration for SLS?

Postby nickfan » Mon Dec 31, 2012 5:54 pm

Hello,

Happy New Year!

I am a new owner of the brand new "Improved SLS-1" kit. It is quite expensive compared to DIY alternatives. But I think it is a good way to show my appreciation of the hard work of DAVID Team. I have been searching for a good and affordable 3D scanning system. I have read lots of info and forum posts here and over 3D3Solutions, Agisoft Photoscan, ScannerKiller and Photomodeler Scanner. I am amazed by the progress of DAVID over the years and even more amazed by the creative forum contributors here.

I think another great improvement in the SLS development is to use a planar calibration board instead of a 90 deg corner. By removing the corner, you remove one source of error - deviation from 90 deg in the corner. Moreover, a big planar target is much easier to make than a big corner when scanning big object like a full body. I think the corner is just a legacy from the laser scanner part.
3D3Solutions, Agisoft Photoscan, ScannerKiller and Photomodeler Scanner all use planer target for lens calibration. Most of them use checkerboard targets. After the lens distortions are corrected, the camera position can be determined by the calibration board alone.
there is even an open source camera calibration software.
http://www.mrpt.org/Application:camera-calib
When the camera is calibrated and oriented, the projector can be calibrated and oriented by analyzing its projected patterns.
Overall, the making of calibration board will be simpler, the data will be more accurate, and scanning of big or very big object will be much easier.
What do you think?


Nick
nickfan
 
Posts: 3
Joined: Tue Dec 04, 2012 5:45 pm

Re: why still use a 90deg corner for calibration for SLS?

Postby Dust » Mon Dec 31, 2012 11:51 pm

I agree. At least have 2 options. The corner setup only requires 2 calibrations, so leave it. In my experience testing the other solutions, the brown.edu example for instance, you have to capture several versions of the flat checkerboard panel. But for better accuracy for us using webcams, this would be a better solution to eliminate distortion.
Projector: Acer K11 Unmodified
Cameras: Logitech C920 - Point Grey Mono Grasshopper 3 - 2.8MP
OS: Windows 7 Ultimate 64-Bit
Processor: Intel i7-3770 Quad Core 3.40GHz
Memory: 16GB DDR3
Graphics: Nvidia Quadro K4000
Dust
 
Posts: 30
Joined: Thu Dec 27, 2012 10:02 pm


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