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Hardware placement setup for 30mm

The place for questions, problems, comments and tips regarding the camera calibration.

Hardware placement setup for 30mm

Postby Gunmaker » Wed May 28, 2014 2:06 am

Hello friends!
I have some questions.

If you see the attached images for calibrate my SLS-2, you can see my doubts respect to the calibration!

Please help me!!

I try to copy the conditions suggestions for the correct calibration hardware, but I can't obtain reproduce the measures and the better focus.

Please, sorry for my bad English!! :mrgreen:

Martin
Attachments
Contact.jpg
This is the suggestion for the hardware
Corner.jpg
Lens calibration.jpg
Www.osvaldogatto.com.ar
Intel i7, 8Gb ram, 2Gb video and DAVID SLS-2 Pro
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Re: Hardware placement setup for 30mm

Postby Gunmaker » Wed May 28, 2014 2:08 am

This is the results for this calibration conditions! :?

Greetings
Martin
Attachments
David1.jpg
Information.jpg
Www.osvaldogatto.com.ar
Intel i7, 8Gb ram, 2Gb video and DAVID SLS-2 Pro
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Re: Hardware placement setup for 30mm

Postby WalterMo » Wed May 28, 2014 8:01 am

Hi Martin,

I don't have the SLS-2 kit nor the DAVID calibration corner from the shop. What I „discovered“:
In the description of the SLS-2 kit is mentioned that this kit would work for scan objects from 60mm-500mm:
https://ssl.david-vision-systems.de/sho ... L-Kit.html

That means for a 60mm object the scale size (which is going along 4 points on the calibration pattern) should also be about 60mm.

So the smallest pattern of the 30mm scale cannot be used. Only the bigger ones (60, 120 and 240mm).

And, don't focus the camera and the projector sharp to the corner walls, focus both devices sharp on your scan object.

Walter

PS. If you like to scan very small objects you should build a separate 30mm-scale-calibration corner. Additionally you have to put a lens in front of the projector's lens and you have to screw in an extension adapter ring between camera and its lens.
http://www.theimagingsource.com/en_US/p ... ics/tubes/

Those things were often done on this forum. :)
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Re: Hardware placement setup for 30mm

Postby Godehardt » Wed May 28, 2014 9:00 am

Hello Martin,
the reconstruction of the depth of an object becomes better if at least one of the angles (vertically or horizontally) is bigger than approximately 25 degrees. If only one angle is big enough then only one set of stripe patterns will be used for the depth reconstruction from the distortion of the stripes on the object as seen by the camera. If both angles are big enough then both sets will be used, which results in a better 3D-reconstruction. For small objects a smaller calibration set has to be used for good results. But then, as Walter states, you have to use close-up lenses for the projector and either a vario-objective or also additional close-up lenses for the camera. In this case, it also often is better to use a calibration corner with a negative angle of 120 degrees instead of 90 degrees. This is discussed in several threads in this forum.
Best regards, Erhard
Erhard Godehardt
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Re: Hardware placement setup for 30mm

Postby Gunmaker » Thu May 29, 2014 3:16 am

Thank you guys for your time and your guide to me understand.
Erhard, the SLS-2 camera have a rule in the base with angles until 30º. When you speak about 25º, you speak of this angle camera regulation?? Or the angles information banner after the calibration process?

Greetings
Martin
Www.osvaldogatto.com.ar
Intel i7, 8Gb ram, 2Gb video and DAVID SLS-2 Pro
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Re: Hardware placement setup for 30mm

Postby Godehardt » Fri May 30, 2014 11:38 am

Martin,
I ment the angles given in the calibration banner. I do not know the content of the SLS-1 or SLS-2 since I built my own rig with another USB camera and projector (pictures of this rig are shown somewhere else in this forum). Maybe that the purpose of the rule is to check the angles between camera and projector, for this please check the manual. Bigger angles than 30 degrees make only little sense since then the camera may "see" not enough stripes as projected onto the object by the projector. With my rig, I can scan objects as small as 25 mm.
Best regards, Erhard
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