Noob question on SLS

Write here about construction, ideas, equipment, tips n tricks etc. related to structured light scanning
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OBNRacerMan
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Re: Noob question on SLS

Post by OBNRacerMan » 02 Nov 2019, 21:27

Alonso wrote:
02 Nov 2019, 20:11
How did you rename the cameras? Did the software use the David drivers by doing this?
It is easy to rename through the registry, but it did not give any useful result, except for displaying the name in the program - i.e. if I try to select the original scanner in the settings - it still says that "there is nothing."
P.S. You can go in a very difficult way, trying to "pull out" the firmware of their camera, thoroughly understand it and write a new name inside ... but I'm not a genius to do this :-)

Rashiga
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Re: Noob question on SLS

Post by Rashiga » 09 Nov 2019, 07:12

What type of lens do you use OBNRacerMan?

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OBNRacerMan
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Re: Noob question on SLS

Post by OBNRacerMan » 09 Nov 2019, 08:38

Rashiga wrote:
09 Nov 2019, 07:12
What type of lens do you use OBNRacerMan?
I use Chinese lenses - ZLKC HM1214MP5 (5.0 Mp 12 mm 2/3” C-mount F1.4 FA / machine vision lenses). At first I wanted to buy analogues - used Pentax, Computar or FUJINON (they turned out to be a little more expensive than the Chinese at the price), but settled on ZLKC.

And if I can get money for cameras with a large matrix (1 "or 1 / 1.2"), then they will have to buy the appropriate lenses like these:
ZLKC KM1214MP8 8Mp 12mm 1" C-mount F1.4 ITS lens

Rashiga
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Re: Noob question on SLS

Post by Rashiga » 09 Nov 2019, 09:18

Thanks for your reply. Btw why did you go for a fixed focal length lens? doesn't it make things difficult when scanning different size objects?

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OBNRacerMan
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Re: Noob question on SLS

Post by OBNRacerMan » 09 Nov 2019, 14:10

Rashiga wrote:
09 Nov 2019, 09:18
doesn't it make things difficult when scanning different size objects?
I have no problems with this — the larger the object, the farther the projector and cameras have to be placed from it — as a result, the proportion of the light spot received from the projector and the camera’s field of view remain unchanged.
In this case, the lens with a fixed focal length minimizes optical distortion (variofocal lens, when moving to a wide viewing angle, the optical distortion increases sharply (several times!))
For this reason, I see no reason to use variofocal lenses (which are also expensive, in addition).

P.S. Of course, there are very high-quality variofocal lenses, the cost of which, however, is beyond the reasonable ;)

Rashiga
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Re: Noob question on SLS

Post by Rashiga » 09 Nov 2019, 19:20

Thank you for the well-explained answer I will also go for a fixed focus lens.

Up to now, I have done the following,

1. To reduce the field of view of the projector I 3d printed an extension tube and moved the whole lens element forward which allowed me to have a smaller field of view to scan smaller objects. But what I found was due to the large aperture the depth of field of the projector reduces significantly. Then I tried to reduce the aperture of the projector lens. But this reduced the amount of light projected. Which was not successful either.
Also with the use of the extension tube field of view gets reduced but the sharpness also reduces. So my conclusion was to buy a projector which is similar to your brand.

2. I also tried reducing the projected area from the projector itself and from the GPU settings to get a finer sinusoidal pattern. But using a finer sinusoidal pattern made the white and black contrast get reduced. So this also didnt work. :(

3. Due to the larger sensor size of the DSRL, I have some issues with the depth of the field. I'm thinking of using a wide-angle lens which allows me to have more depth of field.

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OBNRacerMan
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Re: Noob question on SLS

Post by OBNRacerMan » 09 Nov 2019, 19:49

Rashiga wrote:
09 Nov 2019, 19:20
So my conclusion was to buy a projector which is similar to your brand.
Despite the fact that my projector can focus at a very close distance from a flat object, the depth of field of the projection pattern at close range is also very limited (no more than 50 mm)

Rashiga
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Re: Noob question on SLS

Post by Rashiga » 10 Nov 2019, 03:27

OBNRacerMan wrote:
09 Nov 2019, 19:49
Rashiga wrote:
09 Nov 2019, 19:20
So my conclusion was to buy a projector which is similar to your brand.
Despite the fact that my projector can focus at a very close distance from a flat object, the depth of field of the projection pattern at close range is also very limited (no more than 50 mm)
I see, what about sharpness? From your coin scan, the pattern seemed to be very sharp even at close range.

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OBNRacerMan
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Re: Noob question on SLS

Post by OBNRacerMan » 10 Nov 2019, 08:13

Rashiga wrote:
10 Nov 2019, 03:27
I see, what about sharpness? From your coin scan, the pattern seemed to be very sharp even at close range.
Well, in the range of depth of field, when projected onto the plane of a coin, which is quite perpendicular to the projector, everything will be fine.
And when the calibration angle is in place of the object, it is clearly visible where this field of sharpness of the projector ends.

I drew an approximate layout:
20191110104903s.jpg
Sample graphic diagram

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Micr0
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Re: Noob question on SLS

Post by Micr0 » 10 Nov 2019, 23:11

Depth of field (Focus?) has always been of interest to me. I tried an early laser projector thinking that that may be better, but something about the light produced terrible scans. I guess AV projectors are just not designed to be optimal for what we are doing. :D
µ

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