Noob question on SLS

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Rashiga
Posts: 17
Joined: 13 Oct 2019, 14:45

Re: Noob question on SLS

Post by Rashiga » 11 Nov 2019, 06:11

OBNRacerMan wrote:
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
Thank you for taking the time to illustrate your setup. It seems when focusing at close range due to increased focal length of the projector shallow depth of filed is unavoidable.
Micr0 wrote:
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


Yes, it is true we will always have to obey the rules of optics. And for what we are doing we will need a tailor-made projector with a lens design for our needs.

I was able to narrow down the projection by increasing the focal length of the projector and reducing the projection area from the projector itself and from the video driver options. And managed to get a fairly decent scan. But the issue is there's a larger noise in the scanned surface. Please find the attached images below. The camera frame rate and projector frame rate are in sync.

How can I fix this?
Attachments
20191111_112652.jpg
scan.PNG

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OBNRacerMan
Posts: 57
Joined: 12 Aug 2019, 09:46
Location: Obninsk, Russia

Re: Noob question on SLS

Post by OBNRacerMan » 11 Nov 2019, 07:01

Rashiga wrote:
11 Nov 2019, 06:11
How can I fix this?
I don’t know where your error is. I came across similar when testing different cameras. Here is an example when I connected a high-speed USB2.0 0.9Mp/120fps (1280x720) monochrome camera with a global shutter that produces a signal only in MJPG (also, if I'm not mistaken, it had auto shutter on):
120_test_07b.jpg
120fps MJPG-coded camera
And the same stretch using a typical color USB3.0 5Mp/25fps (2592x1944) camera with YUY2 encoding:
mouse_02.jpg
25fps YUY2-coded camers

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Micr0
Posts: 361
Joined: 15 Nov 2016, 15:20

Re: Noob question on SLS

Post by Micr0 » 11 Nov 2019, 13:45

.jpg can be a very destructive compression scheme depending on the level of compression. I don't really know anything about the other formats. I have been using Y800 with my IS cameras which I believe is a raw monochrome format. It seems to work very well, but I have no experience with the other formats.
µ

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OBNRacerMan
Posts: 57
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Location: Obninsk, Russia

Re: Noob question on SLS

Post by OBNRacerMan » 11 Nov 2019, 17:22

Micr0 wrote:
11 Nov 2019, 13:45
I have been using Y800 with my IS cameras which I believe is a raw monochrome format.
In my cameras, in the basic version, only two formats are available (MJPG when connected via USB2.0, and YUY2 when connected via USB3.0 (but RGB24 is also shown in the properties of cameras displayed by HP3Dscan)).

Also, the other day I tried to install new UVC drivers from Realtek - there is already a choice between RGB24 and YUY2 - but the problem is that with these drivers my cameras (which are already included with great difficulty) freeze, after switching back to the mode scan, from the scan mode ... had to go back to the old ones (2006 UVC from Microsoft). But I managed to notice that in RGB24 mode the picture becomes a bit more contrast than YUY2

Rashiga
Posts: 17
Joined: 13 Oct 2019, 14:45

Re: Noob question on SLS

Post by Rashiga » 13 Nov 2019, 09:39

Micr0 wrote:
11 Nov 2019, 13:45
.jpg can be a very destructive compression scheme depending on the level of compression. I don't really know anything about the other formats. I have been using Y800 with my IS cameras which I believe is a raw monochrome format. It seems to work very well, but I have no experience with the other formats.
Hi Mircro, while searching for DLP projectors I found the following projector which uses a square matrix for its DMD instead of a diamond DMD.

https://www.aliexpress.com/item/3303429 ... f3c4f01d43

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Micr0
Posts: 361
Joined: 15 Nov 2016, 15:20

Re: Noob question on SLS

Post by Micr0 » 13 Nov 2019, 19:46

Rashiga wrote:
13 Nov 2019, 09:39
Micr0 wrote:
11 Nov 2019, 13:45
.jpg can be a very destructive compression scheme depending on the level of compression. I don't really know anything about the other formats. I have been using Y800 with my IS cameras which I believe is a raw monochrome format. It seems to work very well, but I have no experience with the other formats.
Hi Mircro, while searching for DLP projectors I found the following projector which uses a square matrix for its DMD instead of a diamond DMD.

https://www.aliexpress.com/item/3303429 ... f3c4f01d43
That looks interesting. Can you disable the auto focus?
µ

Rashiga
Posts: 17
Joined: 13 Oct 2019, 14:45

Re: Noob question on SLS

Post by Rashiga » 02 Dec 2019, 12:31

Hi Micro,

I contacted the seller but they said that this projector is out of stock. They recommended another projector that also uses square pixels and said that the autofocus feature in it can be disabled.

https://www.aliexpress.com/item/33001301788.html

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