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Deleting Calibration Panel

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

Re: Deleting Calibration Panel

Postby RAYA » Fri Dec 26, 2008 2:14 pm

Hi Gunter

As you know DAVID version 2.2.1 use known 3d object (rightend corner) for calibration but if we change the resolution
the mesh will deformed.

RAYA
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Re: Deleting Calibration Panel

Postby MagWeb » Fri Dec 26, 2008 5:06 pm

Hi RAYA

it was never possible to get right results when you changed the camresolution after calibrating the cam.
Your reference scan result is based on the resolution you grabbed it ( and it can only give right results, if it's the same as during calibration). So if you change the camres after the referencescan, I´m not surprised when you get deformed results....

Gunter
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Re: Deleting Calibration Panel

Postby RAYA » Sat Dec 27, 2008 9:13 am

Hi Gunter

What about optical and digital zooming after calibration as you know many webcam today has digital zooming as an option.

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Re: Deleting Calibration Panel

Postby MagWeb » Sat Dec 27, 2008 10:23 am

Hi Raya,

the same for zooming and tilting: Do not change the zoom-factor or tilt after calibrating the cam . For the scan without background remember: T0 is the moment the cam detects the laser`s beam the first time . If you zoom in after the reference scan, the dam detects the beam later, on another position>>>>> so synchronisation of reference and repetition scan will not fit together....

Gunter
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Re: Deleting Calibration Panel

Postby SAVstudio » Sat Feb 07, 2009 2:48 am

:mrgreen: I may be waaaaay off base here but.......

At any distance of camera to calibration panel, if the laser line is level and the intersection angle is 30 degrees the lines on the panels will be identical (won't they?).

Since David compares the laser line as it scans the surface of an object to the lines on the calibration panels, would it be possible to eliminate the panels (and possibly even calibration) entirely if the camera were fixed at a right angle to it's support and the laser line were mounted above it as in the illustration below? The laser would be locked at 60 degrees down and the line kept level. The set-up would be placed in correct camera/size relationship to the object to be scanned. The laser would be raised or lowered to the correct height for scanning (always at 60 degrees). When the height of the laser is determined and the laser fixed at that height, it is unlocked and allowed to rotate for scanning. The very precise distance from center of camera to center of point of rotation of laser (h) would be the only number necessary to calculate the the angle David would need to generate the reference lines. This could simply be entered in an appropriate field in the interface. Also, if some other angle were more appropriate for a particular object, there could be an 'angle' field (30, 35, 40, 45), each already preprogrammed in to the software.

(Additionally, a second laser placed beneath the camera at an equal distance would be able to scan from below (obviously one laser at a time!).... For the top camera the height would be positive, for the bottom, negative.)

The camera and laser being well fixed to a tripod would mean essentially one piece of 'equipment' to transport.

And if I am completely mistaken.....sorry to take your time.

I am hoping I will soon have better scans than my previous ones to post! Given how unsuccessful they have been I probably shouldn't be making suggestions! :wink:

Steve
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Re: Deleting Calibration Panel

Postby MagWeb » Tue Feb 10, 2009 9:55 pm

Hi Steve,

I´m not quite sure whether I got your idea right.
But I think you´ve some "fixed angle" setup in mind.
I posted some possibilities here:http://www.david-laserscanner.com/forum/viewtopic.php?f=3&t=861
I think you added two other ways?:

-If you would fix your cam/laser combo on wheels ( like on a cam dolly) and move it along the cam´s viewing direction towards the object without changing any angle, that could work too. IF the software knows another parameter: the speed (in relation to the camframes);

-Or you increase the distance laser /cam in a linear way at a constant speed;

there are so many ways to get data with a cam and a laser...and each owns individual advantages!

thanks for your hint,
Gunter
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Re: Deleting Calibration Panel

Postby SAVstudio » Wed Feb 11, 2009 10:25 pm

Guten Tag, Gunter.

First of all I am glad to find your previous comments on fixed angle laser scanning. I had missed them previously. And it makes me veeeerrrry happy to know I am not crazy!

I had a slightly different idea in mind. Once the fixed angle laser is adjusted in height to intersect with the camera at an appropriate point on the object (given the suitable distance of the camera from the object), the laser is released and allowed to rotate freely as in the normal David setup. There still would be some stepper control required to match the actual laser line movement with the 'virtual' line built in to the software (perhaps starting at 0, the exact point at which the laser intersects the camera, and moving upward in + increments, downward in - increments).

I love the idea of freely moving the laser by hand. And I love the idea of carefully sync-ing the software to the laser line via stepper motors. But I am afraid should David move in that direction I will stay behind, because I am having little luck understanding the concept of getting the computer to tell a motor what to do!

This Forum is wonderful and all the users (and Sven and Simon!) are awesome.

Steve
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