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Calibration scale affects laser visibility during scanning

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

Calibration scale affects laser visibility during scanning

Postby ThematVS » Tue Jul 17, 2012 10:22 am

Hi!

Yesterday I was scanning large object and met some effect that can not explain.

My setup:
DAVID Monochrome Camera
Green Laser 15 mW
DAVID v3.4
Laser motion performed by stepper motor

Calibration panels 2.2m width and about 3.2m height, v3 pattern. At these dimensions scale is about 1335 mm. Object size (1.2m) approximately equals to 1/3 of 3D window width, camera looks straight to the corner and placed about 4.5-5m our from the corner at 1.6m height.
Calibration is successful. But when scanning DAVID goes with messages that laser line is not detected on left or right side. Therefore 3D window is empty, no scan results.
But when I change scale to 120mm (everything lower than 200mm) and change nothing else, scanning goes well, clear surfaces, no notices from DAVID.

I'm actually do not know if it calibration problem or scanning. Could somebody help me to clear it up?
ThematVS
 
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Re: Calibration scale affects laser visibility during scanni

Postby WalterMo » Tue Jul 17, 2012 10:59 am

Hi,
Yes, it seems that there is a bug.
I have just tested it here with a 146 mm scale corner. If I set the calibration scale >350 mm I get the same error messages as you.

I used DAVID 3.4, a modified Pro9000 with different lenses.

Other tests will follow.

Walter

Edit: With DAVID 2.6.1 it worked fine.
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Re: Calibration scale affects laser visibility during scanni

Postby Sven » Tue Jul 17, 2012 2:20 pm

Hi,
Yes there seems to be a bug in DAVID 3.x... :(
I will look into it. I'm sure it can be fixed.

Until then, please enter a lower scale value before camera calibration (e.g. factor 2 or 3 or 10 too low). All scan data will be too small by that factor. You can scale them up later.

Thanks
Sven
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Re: Calibration scale affects laser visibility during scanni

Postby ThematVS » Tue Jul 17, 2012 2:30 pm

Sven wrote:Hi,
Until then, please enter a lower scale value before camera calibration (e.g. factor 2 or 3 or 10 too low). All scan data will be too small by that factor. You can scale them up later.


Yes, I came to the same conclusion. Thank you for the fast reply, guys. I was wondering what I'm doing wrong :)
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Location: Chernivtsi, Ukraine

Re: Calibration scale affects laser visibility during scanni

Postby Sven » Fri Jul 20, 2012 9:25 am

I have fixed it for the next version.
We are also working on some other interesting improvements, so I think we will have a 3.5 beta soon. :D
Sven
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