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Calibration Help

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

Calibration Help

Postby everettc4 » Wed Mar 21, 2012 4:45 pm

I’m a newbie to David and this is my first post and I’m looking for camera calibration help because I seem to be missing something in the process. I did accomplish it once and was able to do a series of scans that worked great….but I think my 6 year old bumped the camera and well now I’m back to trying to calibrate for 2 days now with no luck so here I am…

So im looking for the latest tutorial on the new version if anyone can point me in the right direction …

Also it might help to just understand what the camera is looking for and if there are any tools to help users check….I see screen shots of red X Patterns but how do I get to them and how do they help me calibrate..

Does anybody know of a YouTube demo on camera calibration??

My specs.

Structured light
I’m using a closed corner I printed the right and left side patterns at 100% and it measure’s at approximately 152mm for the scale
Camera = Microsoft Lifecam Vx 3000 Webcam

I feel like a dummy.....Thanks a lot in advance for your help..

Everett
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Re: Calibration Help

Postby WalterMo » Wed Mar 21, 2012 8:45 pm

Here is a good demo, probably of DAVID 3.2:

http://www.youtube.com/watch?v=0PqmUMt_wJQ

and here is the official user manual:
http://www.david-laserscanner.com/wiki/ ... l/overview


Walter
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Re: Calibration Help

Postby everettc4 » Thu Mar 22, 2012 2:57 am

Ok still no luck…

I do see that every time I sect a different resolution from the camera selection I am given the green x’s they do not line up with the pattern and I do not see any controls to adjust them to line up…

It just seems to be some sort of luck of the draw wher they fall??????
What are they telling me??

Any help ???

Thanks
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Re: Calibration Help

Postby WalterMo » Thu Mar 22, 2012 4:56 am

Can you post a screen shot?

Then it's easier to understand and to find a solution.
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Re: Calibration Help

Postby everettc4 » Thu Mar 22, 2012 3:52 pm

Here are some screen shots I guess you just need to move the camera to try and line up the x to the pattern...

is the any perticular x s that are more important...or a side to start from what changes the attributes of those little x s??

Thanks agian
Attachments
DScreen_1.jpg
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Re: Calibration Help

Postby everettc4 » Thu Mar 22, 2012 3:54 pm

Not sure what you do with this but maybe it will help
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Dscreen_4.jpg
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Re: Calibration Help

Postby WalterMo » Thu Mar 22, 2012 5:37 pm

The distance of the camera to the calibration corner is much too big. Reduce it to a camera image like here:
http://www.david-laserscanner.com/wiki/ ... alibration

For a successful calibration the camera's image may include all the 70 markers (dots and rings) and nothing else. But you can continue to reduce the distance to a minimum of the 6 rings. These rings are absolutely necessary to „see“ for the camera.

And remove all reflecting things, e.g. the caliper gauge.
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Re: Calibration Help

Postby everettc4 » Sat Mar 24, 2012 10:40 pm

Thanks for all the help I think I got it. I hope this helps other newbies my advice is follow the directions here and keep trying different stuff.
Now I am onto alignment and a motorized turntable can anybody point me in the right direction???

thanks

Everett
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Re: Calibration Help

Postby WalterMo » Sun Mar 25, 2012 10:52 am

What kind of object (weight and sizes) do you intend to turn?

Maybe a simple stepping motor is sufficient to carry the load.

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Re: Calibration Help

Postby everettc4 » Sun Mar 25, 2012 6:04 pm

I'm scanning light weight sock casts of feet for custom ultra marathon running shoes. Right now I putty them down on a five gallon bucket lid and rotate 45 for each scan. I am finding the time putting these together manually would be way better spent building a automated system.. any hardware set up guidance would be much appreciated..

Thanks

Everett
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Re: Calibration Help

Postby WalterMo » Sun Mar 25, 2012 8:13 pm

For loads up to 1kg you can use a turntable like this one:
viewtopic.php?f=6&t=2383&p=14472#p14472

In the meantime I have posted a better controller which can control a 2-axis positioner:
viewtopic.php?f=6&t=4154

If there is an availability of interest, I can modify this device (hard- and software) in such a way that it is well suited to drive a 1-axis turntable.

A suitable stepper motor for its simple drive could be this one:
http://www.phidgets.com/products.php?ca ... _id=3306_0

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Re: Calibration Help

Postby _jack_ » Mon Mar 26, 2012 12:17 am

Walter, I'm really interested too, and could be fantastic to have the upgraded controller hardware and code.
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Re: Calibration Help

Postby everettc4 » Mon Mar 26, 2012 5:50 am

You guys are impressive...is there any plug and play set ups for sale somewhere???
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Re: Calibration Help

Postby WalterMo » Mon Mar 26, 2012 8:39 am

Everett, no, there isn't any plug and play set. But is it a big problem to solder a bit?
Another thing are the mechanical components. And not everyone has a lathe at home.

I think the square platform and the disk could be sawed of plywood and the 4 legs made of roundwood. The only problem is the flange which holds the disk at the motor shaft.

Maybe we will find someone who can produce some. :D
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PVC Turntable.jpg
Example of a simple turntable made of hard PVC
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Re: Calibration Help

Postby everettc4 » Mon Mar 26, 2012 2:38 pm

Ok so lets say I have completed my build on the turn table. Now how do I integrate into david?? is there a link to how to??

thanks
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