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Why does one projector allow faster scanning?

Problems, solutions and discussion about scanning with a video projector and stripe patterns.

Why does one projector allow faster scanning?

Postby micr0 » Thu Feb 25, 2016 7:40 pm

So I am now using a camera that produces 54fps at 1920X1200 resolution. David shows that that is in fact what I'm getting with this camera. However when I scan with the new LG (HD) projector David projects the patterns at the same rate as when i was using the 1200X900 24fps David cam. I experimented and replaced the LG projector with the older Optoma ML550 and the scan rate immediately doubled with no setting changes in David. In the advanced controls under acquisition I have David set to "image content". Why would one projector make such a difference in scanning speed over another all other things being equal? I don't thing it is because the one projector is higher resolution than the other as it is the camera that is dictating the amount of data that is being captured. I'm pretty sure that the refresh rates of both projectors are set the same as well (120hz).

Any one else had this happen? Thoughts?

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micr0
 
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Re: Why does one projector allow faster scanning?

Postby Curiousjeff » Thu Feb 25, 2016 8:45 pm

Just an idea:

Do you have the "TL—testsequence" folder in the David software folder?

If yes, rename it to something else.

It more then doubles my scan time.

Except for surface quality, do you see better resolution scans with the fullhd projector?

Jeff
Panasonic GH4 4K with lens 12-35, Inogeni 4K to USB3 hdmi capture device, projectors: Acer K135/Acer K11/NEC V260X, Canon 60D, macro 60 mm, MagicLantern
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Re: Why does one projector allow faster scanning?

Postby micr0 » Fri Feb 26, 2016 4:21 am

Yes but......

I cant say for sure. The other factor is that this projector does not have the diamond pixels that my other two projector I have. The diamond pixels I think cause distortion around the edges of the horizontal and vertical patterns David projects. So i can't really say how which of these gives the most improvement if at all. I will do some experiments when I get the chance with the new camera and the other lower resolution projectors and see what makes the most difference.

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micr0
 
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Re: Why does one projector allow faster scanning?

Postby micr0 » Sat Feb 27, 2016 5:58 pm

Curiousjeff wrote:Just an idea:

Do you have the "TL—testsequence" folder in the David software folder?

If yes, rename it to something else.

It more then doubles my scan time.

Except for surface quality, do you see better resolution scans with the fullhd projector?

Jeff



There was no folder by that name in the David folder. However I started playing around with screen frame rates in the control panel for my graphics card (AMD FirePro W7100) and changing to 64hz fixed (?) the problem. the patterns are now displayed at twice the rate they were when the frequency was set to 60hz. Interestingly setting the rate to 59hz (58.994hz) gave the best surface quality. I'm at a loss to explain why these changes made such a difference.


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