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Calibration Panel - left and right inner point

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

Re: Calibration Panel - left and right inner point

Postby Vito » Fri Jan 08, 2016 4:42 pm

micr0 wrote:I think that should have been "correct" angle. Too acute or obtuse an angle can cause inaccuracies. When you say "offset", are you talking about the gap where the two panel edges meet? The first column of dots on each panel should be a distance from the edge that is exactly one half the distance of the second column of dots to the first (and the second to the third etc). If the panels edges are not together then this first dimension will be disproportional to the dot spacing of the rest of the panel and could throw your calibration off.

Does this answer your question?

µ


When I talk about offset, I am referring to the main topic of this thread :D From what I understood from previous posts in this thread, David does a correction of the offset (the gap between the panels) that is specific to the panels included in the sls-2. I suspect that something went wrong when I re-assembled the panels. I read, still in the previous posts, that there is a way to verify the calibration with a "virtual calibration panel toggle", but I cannot find it in david v4.
Finally, I asked if someone could provide info on how the original sls-2 panels are supposed to intersect, compared to the photos I posted.
I understand your good intentions, and I thank you, but that "the panel edges should be together" is too generic, I am referring to a specific issue here. :wink:
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Re: Calibration Panel - left and right inner point

Postby pottersfriend » Fri Jan 08, 2016 7:37 pm

It's hard to tell from your pictures but to me it looks almost as if your panels aren't meeting up together further down (see red).
Attachments
Panel Gap.jpg
Panel Gap.jpg (19.66 KiB) Viewed 4403 times
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Re: Calibration Panel - left and right inner point

Postby micr0 » Sat Jan 09, 2016 5:28 am

Vito wrote:
micr0 wrote:I think that should have been "correct" angle. Too acute or obtuse an angle can cause inaccuracies. When you say "offset", are you talking about the gap where the two panel edges meet? The first column of dots on each panel should be a distance from the edge that is exactly one half the distance of the second column of dots to the first (and the second to the third etc). If the panels edges are not together then this first dimension will be disproportional to the dot spacing of the rest of the panel and could throw your calibration off.

Does this answer your question?

µ


I understand your good intentions, and I thank you, but that "the panel edges should be together" is too generic, I am referring to a specific issue here. :wink:


Reread my response as that is not what I said. After asking you to clarify your question, the specifics answer was:

"The first column of dots on each panel should be a distance from the edge that is exactly one half the distance of the second column of dots to the first (and the second and to the third etc). If the panels edges are not together then this first dimension will be disproportional to the dot spacing of the rest of the panel and could throw your calibration off."

To be more specific, in your case "first column" should have been innermost column. And Substitute the first instance of the word "Edge" in the above quoted text for: "The axis formed by the intersection of the two planes formed by the front faces of the calibration panels".

That said, I haven't seen anything that indicates that David can compensate if the calibration panels are out in this respect.

Whats the point of having a calibration standard if it is isn't able to provide a known reference?

µ
µ
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Re: Calibration Panel - left and right inner point

Postby micr0 » Sat Jan 09, 2016 5:51 am

I may stand corrected. In the advanced settings there is a check box to turn on compensation for an offset panel and below that an input box to compensate for one panel being rotated relative to the other. Both offer a warning of distorted calibration results FWIW.

µ
µ
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Re: Calibration Panel - left and right inner point

Postby Vito » Sat Jan 09, 2016 12:32 pm

micr0 wrote:I may stand corrected. In the advanced settings there is a check box to turn on compensation for an offset panel and below that an input box to compensate for one panel being rotated relative to the other. Both offer a warning of distorted calibration results FWIW.

µ


Yes, it is one of the topics of this thread, if you read the previous messages... Let me re-explain.
1) I bought SLS-2, with the original panels. The original panels intersect are connected in a certain way, with a certain distance between them. This creates an offset that the program automatically corrects for.
2) I dropped the panels, they detached. I reattached them by looking at where the glue was. But I suspect that the distance is not correct, and that the automatic correction of david is screwing up my calibration.
3) I asked where is the toggle visibility of the virtual panel in David 4 to verify whether this is the case.

Cheers
V
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Re: Calibration Panel - left and right inner point

Postby Vito » Sun Jan 10, 2016 11:40 am

Ok I found out that the "toggle visibility of panel" is present only in David v3, and I verified that my panel is out of whack (see pics). Could someone tell me how to fix it?
Attachments
Untitled2 (1024x653).jpg
Untitled (1024x546).jpg
Untitled3 (1024x549).jpg
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Re: Calibration Panel - left and right inner point

Postby Jokeri » Sun Jan 10, 2016 5:14 pm

Just for the fun of it, could you calibrate and scan the panels with david v3 and see how it turns out?
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Re: Calibration Panel - left and right inner point

Postby Vito » Sun Jan 10, 2016 6:02 pm

Jokeri wrote:Just for the fun of it, could you calibrate and scan the panels with david v3 and see how it turns out?


Hello, that's exactly what I did, and the results were in picture. It was the only way to have the reference "perfect" panel visible.
I did another couple of tries. I detached again the two panels, and re-attached them using a metal carpenter's square. I made sure not to leave any visible gap between the panels. The results were not much better. There was some improvement when I used the negative corner setting. So in part the problem was due to reflection, and in part to the fact that the panels were no longer perfectly 90°. It would be useful to have the distance between panels when they are new...
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Re: Calibration Panel - left and right inner point

Postby pottersfriend » Mon Jan 11, 2016 3:55 am

I don't have, nor have I seen, a David panel so I don't know how it should go together but I do have an idea to check. Again, your pictures make it hard to see, but something looks off. To me it looks like the panel on the left has its dots farther away then the one on the right. You could measure from the intersection to check if they are different or the same. If they are different then I would suggest to butt the panels up to each other rather than having them meet at their interesting edges (as you have them in your pictures). I attached picture to hopefully show you what I mean. Hope this helps. Good luck.

Panel Help 1.png
Panel Help 1.png (5.11 KiB) Viewed 4343 times

Panel Help 2.png
Panel Help 2.png (6.96 KiB) Viewed 4343 times
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Re: Calibration Panel - left and right inner point

Postby Vito » Tue Jan 19, 2016 11:44 am

pottersfriend wrote:I don't have, nor have I seen, a David panel so I don't know how it should go together but I do have an idea to check. Again, your pictures make it hard to see, but something looks off. To me it looks like the panel on the left has its dots farther away then the one on the right. You could measure from the intersection to check if they are different or the same. If they are different then I would suggest to butt the panels up to each other rather than having them meet at their interesting edges (as you have them in your pictures). I attached picture to hopefully show you what I mean. Hope this helps. Good luck.


Good idea, I will check that.
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