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Calibration panel dot size

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

Calibration panel dot size

Postby vw_bus » Mon Nov 22, 2010 1:10 am

I made a V3 calibration panel with a scale of 500mm. I don't have access to a large format printer, so I accurately marked out the panels and stuck on some dots and rings which I had cnc cut from black vinyl. I have noticed that my pro 9000 camera calibrates very easily with this new calibration panel when set to 1600 x 1200. However, it is much harder to calibrate at 800 x 600. David finds all the dots which are visible in the camera view without thinking anything else visible is a dot, yet the calibration still fails most times.

I remember reading somewhere that David expects to see a minimum number of pixels per dot. My dots do look a bit 'pixely' at 800 x 600, and they are quite small relative to the dots on the printed panels (my dots are 6mm and rings are 12mm). I think the difficulty calibrating at 800 x 600 must be to do with the dots not being big enough. I tried moving the camera closer to the panel (so the camera only sees about half the area of the panels), to increase the number of pixels representing each dot. It does calibrate more easily with the camera closer. Has anyone else come across this with large calibration panels? If so, is there any way to know whether the cause is dots which are too small? I tried looking in the debug window, but it was not obvious to me what the cause of the calibration failure was. Thanks,
vw_bus
 
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Re: Calibration panel dot size

Postby Khalid Khattak » Mon Nov 22, 2010 8:50 am

Please share the calibration panel pictures from the CAM view..
Regards
PC: Dell Inspiron i3, 2.27GHz,4GB RAM,64 bit windows 7
CAMERA:
David CCD Mono USB
LASER:
David 5mW Green line laser
PROJECTOR:
3D LED Mini Projector 250lumens, Native 1024x600
[b]http://free3dscans.blogspot.com/
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Re: Calibration panel dot size

Postby vw_bus » Mon Nov 22, 2010 11:45 am

Thanks for the reply. I don't store any files online (with flickr or similar hosts), which makes posting attachments into forums difficult. Maybe I should set up a flickr account just for posting images into forums, but I think Flickr would limit the files I could attach to just images?

Alternatively I could look into creating a temporary folder on the server which hosts my web site and using ftp to transfer files to it. I have an NAS device which is always on. I could probaly host attachments for forums on my NAS device or on a memory stick plugged into my router's USB host. I need to find out more about the firewall security implications of this first though
vw_bus
 
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Re: Calibration panel dot size

Postby Khalid Khattak » Mon Nov 22, 2010 1:55 pm

You can add picture to this forum .. When you press the Button "Post Reply" you get the screen where you post, below which their is Upload attachment tab...You can browse the image and Addthe file..Just see the following picture...
Attachments
adding bitmap.jpg
PC: Dell Inspiron i3, 2.27GHz,4GB RAM,64 bit windows 7
CAMERA:
David CCD Mono USB
LASER:
David 5mW Green line laser
PROJECTOR:
3D LED Mini Projector 250lumens, Native 1024x600
[b]http://free3dscans.blogspot.com/
Khalid Khattak
 
Posts: 942
Joined: Thu Apr 23, 2009 1:30 pm
Location: Pakistan

Re: Calibration panel dot size

Postby hunkatibor2 » Mon Nov 22, 2010 2:59 pm

Hi
Proba
Khalid you are the light beam of hope real friend . :D :D :D
Tibor
Attachments
sisi-art.pdf
Sisi PDF
(537.43 KiB) Downloaded 304 times
Intel Xeon E5410 2.33GHZ 16GB RAM Windows 7 64bit David 4.5.0
2 Basler A622F camera 2 Tamron Asfirical AF 28-80mm lense
LG DLP Projector PF1500G Canon D40 Tokina 17-70mm 1:2.8-4,5
Humanti Calibration panel system and Alignmed&Two camera
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Re: Calibration panel dot size

Postby eliscio » Sat Dec 11, 2010 1:43 pm

If I read this correctly, 6mm and 12 mm when your scale is 1/2 meter might not work. I vaguely remember a post saying that you need your dots to take up at least 10 pixels...maybe that's just a rule of thumb, but sounds like where the problem is.
www.ai2-3d.com
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eliscio
 
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Re: Calibration panel dot size

Postby cooltech » Sun Dec 12, 2010 6:21 am

Hi all

Has anyone from DS dev's thought up a way to calculate templates based on a relative distance to size of dots and circle points... example 5ft distance = circle point 4 inches. (make a template maker for printing on card) cut out and use to spray on corner wall /plaster board or something. Same with the main 6 circles. You could effectivly make super large caibration matts from these templates.

For example Ive used a4 sheets on a wide 16mm lens (actual 25.6 mm 1.6 body crop). Works fine from the matt at 12 inches. From 36 inches away it would need to be A2 calibration matt. If its a super large object 12 foot... well it would have to be a -A2 (or whatever it would be) SO large just impractical to print. Anyone tried anything to this extreme. (you would need a really powerful laser).
Canon 7d
canon 100mm macro lens
tokina 11-16mm wide lens
canon 100-400 mm prime zoom lens with x 2 extender
canon 50mm 1.4F lens
30mw green line laser module
1mw mitre saw red laser
Merlin automated pano head
2 tripods
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