Not Correct Calibration

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Stive_Rad0
Posts: 35
Joined: 17 Jun 2017, 18:04

Not Correct Calibration

Post by Stive_Rad0 » 17 Jun 2017, 18:38

Hi. I'm using David Scanner for about 2 years. But I never can get a perfect calibration. After calibration the projected check board vertexes do not meet center of circles. I've tested Both of DAvid4 & David5.1 & 5.2.
With Single camera I experiment very bad alignment due to mesh distortion, but in David5 and using Dual camera the problem of distortion come very less and I can get an accuracy of 0.15mm over a 300mm Object (Scanned from 1.2m away from projector). But the vertex error during calibration is still exist.

About my Equipments:
SHARP XR10XL Projector, with 1-1.15 zoom lens, F2.4-2.6, f = 19.0-21.9 mm Lens
Modified Logitech C600 Cameras with 8mm & 12mm fixed lenses (CCTV Lens)
My own Calibration Panel (Made Accurately using CNC)

I Really looking for the day I can Calibrate my System accurately and scan object as accurate as possible.
I use David Scanner for Reverse Engineering of Impellers and some similar parts.
Attachments
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Stive_Rad0
Posts: 35
Joined: 17 Jun 2017, 18:04

Re: Not Correct Calibration

Post by Stive_Rad0 » 19 Jun 2017, 08:52

No One has any Idea & solution?

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Micr0
Posts: 413
Joined: 15 Nov 2016, 15:20

Re: Not Correct Calibration

Post by Micr0 » 19 Jun 2017, 13:17

If your distortion is really .15mm over 300mm, that seems very good for the level of equipment you are using. FWIW the picture of the panel after calibration again looks pretty good for a web cam with a lens. Do you have the Optimize dual camera function enabled?
µ

Stive_Rad0
Posts: 35
Joined: 17 Jun 2017, 18:04

Re: Not Correct Calibration

Post by Stive_Rad0 » 19 Jun 2017, 19:06

Micr0 wrote:
19 Jun 2017, 13:17
If your distortion is really .15mm over 300mm, that seems very good for the level of equipment you are using. FWIW the picture of the panel after calibration again looks pretty good for a web cam with a lens. Do you have the Optimize dual camera function enabled?
Hi. Yes it is 0.15mm over 300mm. Also After alignment of about 3 to 5 scans. I never worked with industrial cameras.
In v5.2 yes, Optimize dual camera function is enabled.
My question is: why some vertexes of checkboard have over 1mm distance to circles centers? they must set exactly at centers to get perfect accuracy.
Also with single camera the accuracy of my system drops to 1mm in 300mm (I think).

Oteck
Posts: 77
Joined: 11 Nov 2016, 21:21

Re: Not Correct Calibration

Post by Oteck » 20 Jun 2017, 13:15

Not certain but this only happens to me when there is any movement in the setup

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Micr0
Posts: 413
Joined: 15 Nov 2016, 15:20

Re: Not Correct Calibration

Post by Micr0 » 20 Jun 2017, 15:16

How did you make those panels? As I posted elsewhere I just mad some 280mm panels and ran into some interesting calibration problems. I don't know if they are related but I plan to spend some time today and see if can figure out whats going on.
µ

Stive_Rad0
Posts: 35
Joined: 17 Jun 2017, 18:04

Re: Not Correct Calibration

Post by Stive_Rad0 » 20 Jun 2017, 17:56

Micr0 wrote:
20 Jun 2017, 15:16
How did you make those panels? As I posted elsewhere I just mad some 280mm panels and ran into some interesting calibration problems. I don't know if they are related but I plan to spend some time today and see if can figure out whats going on.
They are made via building two accurate masks by milling CNC.
Can you do something for me? Tack a photo of your most accurate Calibration Panel by a DSLR Camera (Like Following Photo).
Also please set resolution of your DSLR to minimum and Flash OFF and Anti-vibration OFF and ISO to minimum as photo has a enough brightness.
I can check and compare your DSLR Photo to know its accuracy via Image Processing and using David v3.
Note: Do not do any changes to photo (Rotation, Resize & ...). just send it directly to me.
Capture.JPG

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