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corner distortion

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Re: corner distortion

Postby macdaddyjaz » Thu Sep 15, 2011 9:10 pm

Damn, I have my keystone set to 0 and it still does this.

Anyone got any thoughts on what else it could be? Maybe I will try compensating with keystone. . . . .
-Optoma EP1690 - 1280 x 768
-Canon 40D
-Macbook pro on bootcamp
-Home made adjustable rig mounted on a telescope tripod
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Re: corner distortion

Postby macdaddyjaz » Thu Sep 22, 2011 1:20 am

Any more wisdom on causes of distortion guys?
-Optoma EP1690 - 1280 x 768
-Canon 40D
-Macbook pro on bootcamp
-Home made adjustable rig mounted on a telescope tripod
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Re: corner distortion

Postby MagWeb » Thu Sep 22, 2011 8:15 am

Hi,

don't know, but maybe a possibility:

My old GPU only ran my projector at 1024x768 also it is 1240x768 and the projector stretched the native 4:3 image to 16:9 by default.

This causes that DAVID wrongly "sees" the second monitor as 4:3 (check that in the debugger at the startup of DAVID).

For horizontal stripes only, that wouldn´t matter, but maybe for vertical ones.... which you need in projector calibration....

As said, maybe, just an idea

Gunter
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Re: corner distortion

Postby macdaddyjaz » Thu Sep 22, 2011 8:54 am

Thanks Gunter, that could be a possibility as my setup was using the vertical stripes. I will check through my settings and ensure they are correct.

I will let you know of my progress.

Many thanks,

Chris
-Optoma EP1690 - 1280 x 768
-Canon 40D
-Macbook pro on bootcamp
-Home made adjustable rig mounted on a telescope tripod
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Re: corner distortion

Postby moog » Sat Oct 01, 2011 10:19 am

i've checked the debug window as Gunter suggested, and it is set and detects the correct 1024 x 768 values.
I can't find why its doing it and it's not consistant, yesterday a used 3.1 and i had the disortion , then today i scanned again using the exact same set up with D3.1 and there is no distortion.
until now i've been making small adjustments to the position of the camera and projector, and was starting to think that the position of the projector was the issue, but then today, without changing anything the distortion has gone.
I'm going to leave it exactly where it is, and do it every day with these settings, to see is it comes back again.
LC532-5-3-F(16x65), BenQ PB8220 DLP Projector, logitec quickcam PRO9001, Casio EX-FH20
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Re: corner distortion

Postby moog » Mon Oct 17, 2011 10:03 am

i still can't get rid of this distortion, this is the view of one of my projections, is the fish eye effect supposed to be on it ??
Or could this be what is causing it??
Attachments
curve-2.jpg
LC532-5-3-F(16x65), BenQ PB8220 DLP Projector, logitec quickcam PRO9001, Casio EX-FH20
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Re: corner distortion

Postby macdaddyjaz » Mon Oct 17, 2011 10:38 am

I can't comment on the 'fisheye' effect you are experiencing but I can tell you that I resolved my distortion issue by trying different setups. I have only just stumbled upon a fix so I need to keep trying to understand the parameters to work within but I guess I just lucked out.

I can tell you that I am using a Canon DSLR as a webcam and do not have a noticeable 'fisheye' effect like you are experiencing but as it seems the logitec is the webcam of choice I would be surprised if it is the cause. I seem to remember reading somewhere that the David software compensates for the distortion effect (or maybe it was on another DIY scanner paper) so maybe it isn't working within its acceptable parameters. Could moving back a bit reduce the effect of the fisheye and bring it back to an mount david can compensate for? I am just guessing really. . . . . . but thinking about it I did move my rig further away on its recent distortionless scan.
-Optoma EP1690 - 1280 x 768
-Canon 40D
-Macbook pro on bootcamp
-Home made adjustable rig mounted on a telescope tripod
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Re: corner distortion

Postby moog » Tue Oct 18, 2011 12:00 am

i've moved the projector back as much as i can in the space i have available, but it doesn't help.
You're right, David, does allow for the camera lens distortion, but this is caused by the projector, so i think David may see it as a bent laser line or something like that.
I bought some macro lenses, and a wide angle lens, to try to expand the projection size at close up distances, I've only had a quick go with them, as they seem to dramatically reduce the depth of focus
LC532-5-3-F(16x65), BenQ PB8220 DLP Projector, logitec quickcam PRO9001, Casio EX-FH20
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Re: corner distortion

Postby MagWeb » Tue Oct 18, 2011 8:19 am

Hi Moog,

this reminds me on the cushion distortion of CRT monitors (our old big monitors). Those monitors had a built in control to correct these distortions. Maybe your projector or your graphics card has this option too?
I remember a PROCESSING script (at their forum) where you could display a movie on a curved surface. It could be a chance too to use it to correct your projector distortions.

yes, the absolute depth of focus drops using close-up-lenses but it should be rather equal relative to the size of projection. Another thing may be irregular distortions caused by this sort of cheaper lenses.

Gunter
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Re: corner distortion

Postby moog » Tue Oct 18, 2011 9:51 am

Gunter,
Thanks for your input, I've checked my projector for any such settings, and the only one which will do any corrections is the keystone. Until now I've had keystone set on 0 (and I've not used any extra lenses)
I projected a grid onto the panels, and adjusted the keystone, to improve the projection, and the best setting was at 6
i then calibrated David and scanned the panels. You can see here an improvement, but still slightly fish eyed.
Also my nvidia quatro drivers don't seem to allow any advanced adjustments, here are jpegs of what's available.

I'm wondering, (as an extra feature) should we not have the ability within david to correct this projector distortion??
Can you recall where to find the script you mention?
Attachments
keystone.jpg
nvidia-1.jpg
nvidia-2.jpg
LC532-5-3-F(16x65), BenQ PB8220 DLP Projector, logitec quickcam PRO9001, Casio EX-FH20
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Re: corner distortion

Postby balto001 » Sun Nov 20, 2011 6:37 am

I have this problem too, it was working fine before and now its just distorted like an 'S'
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Re: corner distortion

Postby balto001 » Sun Nov 20, 2011 3:58 pm

im not sure why but I fixed the problem. I have 3 cameras so I decided to place one of the camera parallel to the one that doesnt calibrate correctly and used that one instead and changed the lens for the one that didnt work. It calibrated correctly and perfectly so I decided to retry the other camera that didnt seem to work and.... pouf everything is correct. No distortion or anything at all...
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Re: corner distortion

Postby moog » Mon Nov 21, 2011 12:07 am

I've not managed to correct my distorsion, and have failed to find a solution, I've ordered another lens for my pro9001, but if this fails to fix the problem, i may have to give up..
LC532-5-3-F(16x65), BenQ PB8220 DLP Projector, logitec quickcam PRO9001, Casio EX-FH20
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Re: corner distortion

Postby Khalid Khattak » Fri Sep 13, 2013 4:27 pm

moog do you still have distortion issues?
PC: Dell Inspiron i3, 2.27GHz,4GB RAM,64 bit windows 7
CAMERA:
David CCD Mono USB
LASER:
David 5mW Green line laser
PROJECTOR:
3D LED Mini Projector 250lumens, Native 1024x600
[b]http://free3dscans.blogspot.com/
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Re: corner distortion

Postby moog » Mon Sep 16, 2013 8:42 am

no, I fixed it by setting my projector resolution to a different figure I use 1280 x 1024 I don't know why it works but it fixed it here.
basically I kept the same ratio (ie. 1024 x 768) but increased it as far as the graphics card will allow, without giving an error
LC532-5-3-F(16x65), BenQ PB8220 DLP Projector, logitec quickcam PRO9001, Casio EX-FH20
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