Alignment problems

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erapip
Posts: 41
Joined: 16 Dec 2016, 07:16

Re: Alignment problems

Post by erapip » 03 Oct 2017, 18:38

@3dxcan when you try and share the scan will leave place for discusion. 2scan in DAVID =10 scan in FLEX. It depends for what you want to judge!!!
I know for markers tha help alignment in FLEX but didnt have time to test.
If so share your scan data.

@Micr0 Thanks! I will find time to post setup.

3dxcan
Posts: 74
Joined: 02 Jun 2017, 17:21

Re: Alignment problems

Post by 3dxcan » 03 Oct 2017, 20:09

erapip wrote:
03 Oct 2017, 18:38
@3dxcan when you try and share the scan will leave place for discusion. 2scan in DAVID =10 scan in FLEX. It depends for what you want to judge!!!
I know for markers tha help alignment in FLEX but didnt have time to test.
If so share your scan data.

@Micr0 Thanks! I will find time to post setup.
I'm not here to say my scans are better than yours. Its actually quite the opposite. Please read the the thread topic and see the first post.

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

Re: Alignment problems

Post by Stive_Rad0 » 06 Oct 2017, 18:46

Hi. I've found something new and very useful for who has problems with alignment.
I have same problem, but I'm sure it is because of Projector. I have a SHARP Projector. Never successful alignment with single camera (Over 1.5mm Deviation per 200mm object). But with dual camera it is reduced down to 0.5mm.
And now a way to reduce the error downto 0.15. Just setup your Camera exactly at the same Angle regards to Projector (H & V angles).
angle deviation must be kept under 0.1deg.

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Micr0
Posts: 272
Joined: 15 Nov 2016, 15:20

Re: Alignment problems

Post by Micr0 » 06 Oct 2017, 21:20

Stive_Rad0 wrote:
06 Oct 2017, 18:46
Hi. I've found something new and very useful for who has problems with alignment.
I have same problem, but I'm sure it is because of Projector. I have a SHARP Projector. Never successful alignment with single camera (Over 1.5mm Deviation per 200mm object). But with dual camera it is reduced down to 0.5mm.
And now a way to reduce the error downto 0.15. Just setup your Camera exactly at the same Angle regards to Projector (H & V angles).
angle deviation must be kept under 0.1deg.
That's the first rule of debugging any system.If you can eliminate inaccuracy that is always better than trying to compensate in software. Have markings on both of my camera mounts and always have the cameras symmetrically positioned about the projector. kinda just assumed everyone thought the same.
µ

3dxcan
Posts: 74
Joined: 02 Jun 2017, 17:21

Re: Alignment problems

Post by 3dxcan » 07 Oct 2017, 03:09

Micr0 wrote:
06 Oct 2017, 21:20
Stive_Rad0 wrote:
06 Oct 2017, 18:46
Hi. I've found something new and very useful for who has problems with alignment.
I have same problem, but I'm sure it is because of Projector. I have a SHARP Projector. Never successful alignment with single camera (Over 1.5mm Deviation per 200mm object). But with dual camera it is reduced down to 0.5mm.
And now a way to reduce the error downto 0.15. Just setup your Camera exactly at the same Angle regards to Projector (H & V angles).
angle deviation must be kept under 0.1deg.
That's the first rule of debugging any system.If you can eliminate inaccuracy that is always better than trying to compensate in software. Have markings on both of my camera mounts and always have the cameras symmetrically positioned about the projector. kinda just assumed everyone thought the same.
Do you have the same 0.15mm accuracy in alignments? Or mismatch of the scans away from the center of shots also happens when cams are symmetrical?

User avatar
Micr0
Posts: 272
Joined: 15 Nov 2016, 15:20

Re: Alignment problems

Post by Micr0 » 07 Oct 2017, 17:54

3dxcan wrote:
07 Oct 2017, 03:09
Micr0 wrote:
06 Oct 2017, 21:20
Stive_Rad0 wrote:
06 Oct 2017, 18:46
Hi. I've found something new and very useful for who has problems with alignment.
I have same problem, but I'm sure it is because of Projector. I have a SHARP Projector. Never successful alignment with single camera (Over 1.5mm Deviation per 200mm object). But with dual camera it is reduced down to 0.5mm.
And now a way to reduce the error downto 0.15. Just setup your Camera exactly at the same Angle regards to Projector (H & V angles).
angle deviation must be kept under 0.1deg.
That's the first rule of debugging any system.If you can eliminate inaccuracy that is always better than trying to compensate in software. Have markings on both of my camera mounts and always have the cameras symmetrically positioned about the projector. kinda just assumed everyone thought the same.
Do you have the same 0.15mm accuracy in alignments? Or mismatch of the scans away from the center of shots also happens when cams are symmetrical?
Depending on the scale I'm calibrating too and the shape of the scan subject, That's about right (+- .1mm~). Better If I'm really careful. Higher precision sometimes requires running the calibration sequence more than once.
µ

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

Re: Alignment problems

Post by Stive_Rad0 » 08 Oct 2017, 06:28

Micr0 wrote:
07 Oct 2017, 17:54
Depending on the scale I'm calibrating too and the shape of the scan subject, That's about right (+- .1mm~). Better If I'm really careful. Higher precision sometimes requires running the calibration sequence more than once.
Micro, can I ask what you mean "Higher precision sometimes requires running the calibration sequence more than once"? How do you check the precision and how you can get better?

User avatar
Micr0
Posts: 272
Joined: 15 Nov 2016, 15:20

Re: Alignment problems

Post by Micr0 » 08 Oct 2017, 13:49

Stive_Rad0 wrote:
08 Oct 2017, 06:28
Micr0 wrote:
07 Oct 2017, 17:54
Depending on the scale I'm calibrating too and the shape of the scan subject, That's about right (+- .1mm~). Better If I'm really careful. Higher precision sometimes requires running the calibration sequence more than once.
Micro, can I ask what you mean "Higher precision sometimes requires running the calibration sequence more than once"? How do you check the precision and how you can get better?
Generally I can tell how good my alignment is by how well David displays the checkerboard after the calibration sequence. This is important feedback. The key is also looking at the alignment of the corners that are at the very periphery of the envelop. If they aren't perfect, Adjust the position of the equipment to the corner and try again. This may mean a slightly wider camera/projector angle etc. If your calibration corners aren't perfectly made there are parameters in the advanced settings to help compensate for this but, I stay away from those unless absolutely necessary.
µ

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

Re: Alignment problems

Post by Stive_Rad0 » 08 Oct 2017, 18:20

Micr0 wrote:
08 Oct 2017, 13:49
Generally I can tell how good my alignment is by how well David displays the checkerboard after the calibration sequence. This is important feedback. The key is also looking at the alignment of the corners that are at the very periphery of the envelop. If they aren't perfect, Adjust the position of the equipment to the corner and try again. This may mean a slightly wider camera/projector angle etc. If your calibration corners aren't perfectly made there are parameters in the advanced settings to help compensate for this but, I stay away from those unless absolutely necessary.
Interesting. for me, some of the projected corners are over 1mm deviated from circle centers. I'm sure my calibration board is made perfectly, but over 1mm error is unacceptable. it is interesting to say with this error I can get alignment well. BUT only with dual camera and adjusting cameras exactly at the same angle. (with single camera corner deviation is the same, but alignment error is over 2mm). Why I can't get Corners at center of circles?
Projector problem or something else?

User avatar
Micr0
Posts: 272
Joined: 15 Nov 2016, 15:20

Re: Alignment problems

Post by Micr0 » 09 Oct 2017, 14:19

Stive_Rad0 wrote:
08 Oct 2017, 18:20
Micr0 wrote:
08 Oct 2017, 13:49
Generally I can tell how good my alignment is by how well David displays the checkerboard after the calibration sequence. This is important feedback. The key is also looking at the alignment of the corners that are at the very periphery of the envelop. If they aren't perfect, Adjust the position of the equipment to the corner and try again. This may mean a slightly wider camera/projector angle etc. If your calibration corners aren't perfectly made there are parameters in the advanced settings to help compensate for this but, I stay away from those unless absolutely necessary.
Interesting. for me, some of the projected corners are over 1mm deviated from circle centers. I'm sure my calibration board is made perfectly, but over 1mm error is unacceptable. it is interesting to say with this error I can get alignment well. BUT only with dual camera and adjusting cameras exactly at the same angle. (with single camera corner deviation is the same, but alignment error is over 2mm). Why I can't get Corners at center of circles?
Projector problem or something else?
Are your advance settings all set to the default?

P.S. The first set of panels I make I thought were perfect too. Then I found a simple mistake in the parts that hold the panels that was throwing the whole thing off.
µ

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