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Zoom

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

Zoom

Postby santo » Fri May 29, 2009 9:36 am

Is it possible to zoom after camera calibration ?
What is the best calibration for a small object?

Sory for my languadge

Sank you
David Laserscaner version 2.4.5 avec licence, Centrino dual core 2 GHz, 4 GOct mémoire, non focusable laser rouge, moteur pas à pas + réduction de 1 / 470.
  Pierre
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Re: Zoom

Postby MagWeb » Fri May 29, 2009 10:00 am

Hi,

no, don´t zoom (or tilt or move) the cam after calibration - never - basic rule!!! Do even not change the cam`s focus.
.

Allways use the automatic calibration. Also the eraser tab uses this calibration mode. Use the eraser to hide things as screws, hinges or someting that doesn´t belong to the calibration pattern and might be detected as being a marker....

For small objects simply scale down a printout to the wished size, measure the length of the "scale" line and put in that value in the scale field on DAVID´s calibration page.

Gunter
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Re: Zoom

Postby Synapse3D » Fri May 29, 2009 9:38 pm

Dear Santo,

I am agree with Magweb as i tried at my beginning to make the things easier using the zoom of the camera (before calibration and with no modifications after) :lol: .
But using the zoom is bad because you get much more noise (using the Logitech 9000 from the kit, don't know for other cams) because of the "numerique" zoom. Maybe with an optical zoom, that can works better (no electronical noise). Thus, to scan little objects, i print little patterns (just up to the size of the object), and let the zoom to 100%. This way, your objects will be in a big area of your camera view. As an example, i have scanned a 8mm object using a pattern having a scale of 9mm (do not forget to measure the scale of your printed pattern to enter it into the calibration step of David as Magweb mentioned).

Best regards,

Ben.
Dell T7400 workstation Dual Xeon Quad cores, 16GB RAM, QuadroFX 4600, Dual Dell 23 inches displays, XP Pro x64, David Laser starterkit 2.3.
http://www.ima-solutions.fr
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