Alignment problems

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3dxcan
Posts: 73
Joined: 02 Jun 2017, 17:21

Re: Alignment problems

Post by 3dxcan » 18 Aug 2017, 06:54

Curiousjeff wrote:
17 Aug 2017, 21:17
One possible approach is to select all the scans, then right click and select "shrink border" (or whatever it is called. I am not in front of my computer). You can repeat as many times as you like as long as you preserve overlapping areas. Save you project before each step in case you need to revert back.

You can also use the depth filter when scanning.

A long time ago, I asked the David team to implement a similar filter to the depth filter but for cutting out top/bottom/left/right sides of the scan. This was never done.
shrink border only wipes off very small amount off the borders, i need to shave off maybe one third of the scan area from the border.
Is anyone getting good alignment using Manual sequence scan? I only get acceptable results if I choose to align using free/contact pair selection method.

Curiousjeff
Posts: 121
Joined: 16 Nov 2016, 22:31

Re: Alignment problems

Post by Curiousjeff » 18 Aug 2017, 07:13

as mentioned, you can repeat many times the shrinking.

If you apppy the "shave" to all scans at the same time and do it multiple times, should take less then a minute or two, depending on the amount of scans you have.

Another possibility, but I have not tried it is to make a lens gobo to restrict the field of view of the camera to the area you want.

Narmella does not seem that problem. Maybe you should test the DSLR option (in David 4 only).

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Micr0
Posts: 264
Joined: 15 Nov 2016, 15:20

Re: Alignment problems

Post by Micr0 » 18 Aug 2017, 12:45

Jeff, this just reminded me: 3dxcan, have you tried the results filtering (min and max depth) under the Structured light setting in advanced?
µ

3dxcan
Posts: 73
Joined: 02 Jun 2017, 17:21

Re: Alignment problems

Post by 3dxcan » 18 Aug 2017, 17:47

I have tried but when i enter a number, it completly deletes the entire scan. I tried large and small numbers.
What's the unit of that number?

Micro, You do large scans too as far as i remember. Without a large calibration panel, do you get good alignments using your regular ~200mm calibration panel? Profesional scanners can do so.

Does 2nd camera help to get better alignments?

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Micr0
Posts: 264
Joined: 15 Nov 2016, 15:20

Re: Alignment problems

Post by Micr0 » 18 Aug 2017, 18:37

My most used panels are 300mm (I had 1000mm panels made for the sculpture job). The second camera helps if you don't scan in extended mode. however I almost always scan in extended mode. Alignment hasn't really been a problem recently. Having said that I've been doing objects that are very easy to scan.
µ

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

Re: Alignment problems

Post by Stive_Rad0 » 18 Aug 2017, 19:02

Hi
did you try another Projector?
I have some topics in this forum and have exactly your problem. afterrrrrrrrr 2 years.
before v5 of david, I have very big problems with alignment. by adding second camera problem reduced but don't solved completely. I'm not satisfied yet, but by this way I found the problem is projector. because in all document about structured light scanning it is mentioned second camera will reduce errors caused by projector and environment. by this way, I worked alot on my projector lens and succeed to reduce the problem but not completely. (my Projector is a high end old DLP projector. but its lens is not suitable for SLS).
till now I haven't buy a new projector. But I can suggest you to try some other projector (same model as Narmella or Micr0 or k135 or some Optima models).
If you don't solve projector problem, dual camera only can reduce problem, not completely solve it.

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Micr0
Posts: 264
Joined: 15 Nov 2016, 15:20

Re: Alignment problems

Post by Micr0 » 18 Aug 2017, 19:29

Projector lenses are another weak link in this chain. Many of the more expensive Sl systems that use off the shelf projectors have replaced the lens. It is something I would like to do but don't want to spend the $ on that adventure right now. Some day.
µ

spark
Posts: 44
Joined: 06 Mar 2017, 20:44

Re: Alignment problems

Post by spark » 19 Aug 2017, 20:22

thank you for telling me about the function min / max depth filtering.
is the value in mm? and what is its reference? the crosshair of the calibration? anybody using it?
regards, spark

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avogra
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Posts: 99
Joined: 11 Nov 2016, 17:27
Location: Munich, Germany
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Re: Alignment problems

Post by avogra » 20 Aug 2017, 21:49

yes, the reference is in mm from the lens of the first camera

NARMELLA
Posts: 18
Joined: 19 Apr 2017, 05:53

Re: Alignment problems

Post by NARMELLA » 21 Aug 2017, 02:50

avogra wrote:
20 Aug 2017, 21:49
yes, the reference is in mm from the lens of the first camera
I prefer to use image grabber instead of live scanning to have more depth of field .
Unfortunately david can't detect out of focus portions automatically .

NARMELLA
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