Projector Calibration Question

Home Forums AR Sandbox Forum Projector Calibration Question

This topic contains 6 replies, has 2 voices, and was last updated by  Oliver Kreylos 4 years, 5 months ago.

Viewing 7 posts - 1 through 7 (of 7 total)
  • Author
    Posts
  • #100819

    dalbanese
    Participant

    Thanks so much for this wonderful project.

    Almost finished my sandbox for my young daughter (although secretly I have had a pretty fun time building it as well)

    I think my final issue is the projector calibration step (7) No problems running the calibration, the tie points and camera matrix look at least reasonable, and the red lines follow the target very nicely after I do 12 tie points. When I run the Sandbox however the depth topology is always shifted over an inch and to the side about 2 inches.

    I have used the -fpv command when starting the sandbox.

    Could it be my projector? I am using a Epson G5150 which I think has a native resolution of 1920 x 1080. I have tried as many combinations of projector aspect ratio, ubuntu display ratio, and CalibrateProjector -s switch option as I could think up.

    Any thoughts?

    Here is a link to a picture showing the issue with a box of screws.

    #100822

    Oliver Kreylos
    Keymaster

    That shouldn’t happen. Make sure that the display windows in CalibrateProjector and SARndbox are the exact same position and size, ideally both full-screen with no title bar or desktop panels showing. See this other thread on how to achieve that.

    #100829

    dalbanese
    Participant

    I have been using the Vrui.cfg to fire up both the CalibrateProjector and the SARndbox app which both seem to be running full screen.

    Any other diagnostic info I could pass along?

    Thanks

    #100839

    Oliver Kreylos
    Keymaster

    Do you have a set of pictures showing how the red crosshairs track your calibration target in CalibrateProjector, and then how features don’t line up later in SARndbox?

    #100840

    Oliver Kreylos
    Keymaster

    Forgot to mention: Always run your projector at native resolution (1920×1080), and pass that resolution to CalibrateProjector when you’re calibrating.

    Also make sure that your projector is using the full 1920×1080 frame. By default many don’t, to account for view borders in broadcast HD. Use the test pattern displayed by XBackground (part of Vrui package), and ensure that you see the white lines around the borders, and the full circles in the corners. There is usually a “show pixels 1:1” or some similar item in the projector menu somewhere.

    #100844

    dalbanese
    Participant

    I did manage to get everything working. Though perhaps not as optimally as I could.

    I ran through your recently updated calibration steps. I may missed downloading the kinect calibration in my original setup. Or perhaps not included all the recommended flags runnings the Sandbox application.

    I am running the projector at 4:3 and 1024×768 despite the resolution being 1920×1080 native. I do pass that along in the calibration step (though I think they are the defaults. I haven’t noticed any degradation in image quality.

    I built the physical sandbox with a 4:3 aspect ratio so I would like to keep the aspect ratio the same as the physical installation.

    Ill see if i can replicate my previous issue so it can be known for future builders. Right now I can’t run the water simulation on my old workstation, but I’ll get my new workstation (Haswell-E and a GTX 980) dual booting ubuntu and give it a try with the water simulation.

    Thanks for all the help. Once I get it all setup I am interested in extending the software a bit (think UHF and the marble in the oatmeal) for my 2 year old.

    Dominic

    #100848

    Oliver Kreylos
    Keymaster

    Especially the contour lines will be much crisper if you run the projector at its native resolution. Upscaling from 1024×768 to 1440×1080 introduces some aliasing because it’s a non-integer ratio.

    If you could generate a video signal of 1440×1080 from your graphics card it would be the best of both worlds, as you’ll get a 4:3 aspect ratio and native pixel resolution.

Viewing 7 posts - 1 through 7 (of 7 total)

You must be logged in to reply to this topic.

Comments are closed.