How is the scan quality related to the projector's resolution?

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kth307000
Posts: 19
Joined: 17 Jul 2020, 15:35

How is the scan quality related to the projector's resolution?

Post by kth307000 » 31 Jul 2020, 10:29

Hello
This forum has helped me a lot.

Currently, the camera uses 5M resolution, but the projector uses an older Toshiba model (1024X768).

As shown in the picture below, the scan result is not smooth and embossing feeling and streaking occurs.
Occasionally there are no streaks, but almost all of them are streaks on the surface, I wonder if it is related to the projector resolution.

Otherwise, I am wondering if there is a problem with the correction or a problem with the brightness adjustment.

I think that the brightness control has been set enough in its own way through many tests.

Help us know what kind of know-how you need to scan the surface smoothly

Thank you always.
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Untitled-1.jpg
The surface is not smooth and has streaks

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OBNRacerMan
Posts: 173
Joined: 12 Aug 2019, 09:46
Location: Obninsk, Russia

Re: How is the scan quality related to the projector's resolution?

Post by OBNRacerMan » 31 Jul 2020, 13:34

Artifacts from a low-resolution projector look like evenly spaced very small stripes or rectangles (in fact, these are traces of the projector's matrix pixels). Ripples are usually caused by inaccurate timing of the camera's shutter speed relative to the frequency of the projector. In inexpensive cameras it is not possible to set the shutter speed accurately, up to 0.0001s
And the available values ​​1/128, 1/64 and a projector with 60Hz will give stripes both when viewed on the screen and on the resulting model. Reducing the frequency of the projector to 50Hz helped to some extent with old inexpensive cameras.
But I quite agree that the low resolution of the projector also negatively affects the quality of the scan.
The higher the resolution of the camera, the stronger the disadvantages of the projector begin to affect.

kth307000
Posts: 19
Joined: 17 Jul 2020, 15:35

Re: How is the scan quality related to the projector's resolution?

Post by kth307000 » 01 Aug 2020, 04:49

OBNRacerMan wrote:
31 Jul 2020, 13:34
Artifacts from a low-resolution projector look like evenly spaced very small stripes or rectangles (in fact, these are traces of the projector's matrix pixels). Ripples are usually caused by inaccurate timing of the camera's shutter speed relative to the frequency of the projector. In inexpensive cameras it is not possible to set the shutter speed accurately, up to 0.0001s
And the available values ​​1/128, 1/64 and a projector with 60Hz will give stripes both when viewed on the screen and on the resulting model. Reducing the frequency of the projector to 50Hz helped to some extent with old inexpensive cameras.
But I quite agree that the low resolution of the projector also negatively affects the quality of the scan.
The higher the resolution of the camera, the stronger the disadvantages of the projector begin to affect.
OBNRacerMan
Thank you for your valuable answers.

My projector is not frequency adjusted, so I am going to purchase and test a new projector.

After looking at the answers that the projector resolution affects the scan results, we think of a combination of projectors with high resolution.

In addition, we will make various attempts to improve the scan quality.

Have a nice day~

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OBNRacerMan
Posts: 173
Joined: 12 Aug 2019, 09:46
Location: Obninsk, Russia

Re: How is the scan quality related to the projector's resolution?

Post by OBNRacerMan » 01 Aug 2020, 10:02

I myself use a low resolution projector (1280x720). I plan to buy a FullHD projector for the future (but now it is too expensive for me, given the local currency rate)

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Micr0
Posts: 426
Joined: 15 Nov 2016, 15:20

Re: How is the scan quality related to the projector's resolution?

Post by Micr0 » 02 Aug 2020, 22:26

The orientation of the DLP mirrors can make a difference. Most projectors have the mirrors oriented 45° from horizontal giving a diamond pattern to the "window screen" (the space between the mirrors which you can see if you look closely at the projected image. The higher the resolution of the projector, the more mirrors and the finer the window screen. Since David reads the distortion of vertical and horizontal black and white lines projected on to you subject. the sharper ( or higher the fidelity) of the projections the better. With Diamond pixels, the edges will be by default not as sharp as with "Square" pixels. The higher the resolution of your cameras the more this matters. That said the advantage of a 1080p over 720p projector is not as pronounced as switching to a higher resolution camera providing the projectors both have square pixels.
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