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Object is open

The place for all topics related to the 'Shapefusion' tool of DAVID.

Object is open

Postby Franky » Tue Jan 26, 2010 9:47 pm

Hello,

I have tried my first scan without background. This works fine, i took 12 scans around my model.
When i align the scans the Object has a gap on the end. That went wrong?
I know this problem when i scan with backgrund an the angle of the backgrount is not correct but in this case i have no background

Regards Frank
Franky
 
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Postby hal » Tue Jan 26, 2010 10:33 pm

Hello and welcome Franky,

Did you use a stepper motor and a controller, for laser rotation/linear movement?
If not, probably this is the answer to your question.
If you scan without panels and without a precise system/device to drive your laser in junction with David software, you could obtain wrong and distorted scans. If distortion is little, you can adjust manually every single scans after a first alignment, but if deformation is big, no way to obtain a good alignment.
And if your background, for calibration, isn't perfect, you must add to your scans an other % of errors/deformations.

Regards,
Mattia
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Re: Object is open

Postby Franky » Tue Jan 26, 2010 10:56 pm

Hello Mattia,

first thanks for the welcome :D
I Use a Stepper Motor for Laser movement.
My Background should be OK it workt perfect when i scan with the beckground.
I will try another scan with new background calibration probably there was a problem that i can´t see without the pattern.


Regards Frank
Franky
 
Posts: 13
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Location: Karlsruhe Germany

Re: Object is open

Postby MagWeb » Tue Jan 26, 2010 11:15 pm

Hi,

to check your planeless system:

Do the reference scan without an object and disable the background filter (backgroundFilterFactor to a negative value);
watch the result A - does it fit to the grid in the 3D window?
Do a repetition scan without an object with disabled background filter scanning the empty corner again;
watch the result B - does it fit to the grid?
This is my routine

If B is equal A you can be rather sure that your planeless scans will fit to each other. Otherwise there are a lot of possible errors that may cause some distortion.

Gunter
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Re: Object is open

Postby Franky » Sat Jan 30, 2010 11:05 am

Hello,

i tried the procedure from Gunter, the two scans will absolute fit.
Then i scan a cube and the angles are smaler than 90 degrees :?

Regars Frank
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Location: Karlsruhe Germany


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