Projector Question

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This topic contains 8 replies, has 4 voices, and was last updated by  David_ZA 4 months, 1 week ago.

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  • #103238

    David_ZA
    Participant

    Good day all,

    I am looking at making an AR sandbox for my geography department.
    I am able to get all parts within budget except a short throw projector. (they are very expensive here)

    My Question is:
    I have a normal NEC projector with a 1 meter (40″) width throw distance of 1.9 meters. In other words the projector has to be 1.9 meters away from the top of the sandbox. Is this viable and calibrate-able?

    Thanks in advance for any assistance.
    David

    #103245

    chuck.sieck
    Participant

    I don’t know about your specific projector but we are using a cheap Epson with digital zoom capabilities and it works great. A short throw is NOT required.

    #103263

    liudr
    Participant

    David,

    My system is about the same situation as yours, with a regular projector. It’s pretty tall! One thing I learned is that the Kinect should be mounted closer than the regular projector, around 1.2m (45″) from the bottom of the box. With Kinect mounted so far away as our regular projector, we were unable to calibrate the projector with targets.

    #103264

    David_ZA
    Participant

    Liudr,

    Thanks for confirming my suspicion.
    My sandbox is being made as we speak and I have taken the sensor distance into account.

    I will use this thread to post pictures of the final product for those that would seek help in future.

    #103270

    liudr
    Participant

    I found reference here. Dr. Kreylos recommends the Kinect 40″ above the bottom of the sandbox.

    http://idav.ucdavis.edu/~okreylos/ResDev/SARndbox/Instructions.html

    Read the description below the figure.

    #103279

    David
    Participant

    Hey David,

    We had the same issue, we need the larger projecting distance but without the kinect throwing shadows on the sand or the whole structure being ridiculously tall. We ended up using a mirror to extend the path of light and that works really well for us. I talked about it in slightly more detail here. Maybe that setup can work well for you. We are planing to publish instructions/documentation for the physical build in a few months.

    Greetings,
    David G.

    #103281

    liudr
    Participant

    David G.,

    I’d love to see how you placed the mirror in the path of the projected image. Let us now when you have docs published.

    John

    #103284

    David
    Participant

    we don´t have a great picture yet, consider this work in progress.
    projector setup.

    https://drive.google.com/open?id=0B3xXY5j2KFXAOXJDYW1vTHpaVUE

    i will make sure to post a link to all our documents in this thread once they are done.
    Our required projection distance was calculated to be 1,3m; i will measure the actual path of light next time i get a chance.

    Another note on correct mounting hight: The kinect has a 45° field of view so for a 75x100cm box it needs to be mounted 100 cm above the top of the walls, which are the maximum sand surface height. We only found out that the color image has a slightly wider field of view than the actual depth sensor when it was too late so consider that before choosing a permanent mounting hight for your kinect.

    David

    sorry if this post shows up twice, I had some issues with my internet connection

    #111101

    David_ZA
    Participant

    Hi everyone,

    Sorry for the necro, but a promise is a promise.
    I said I would post something when it is done.

    My buddy (fellow teacher) made this video while we were testing it after first calibration:

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