• Hello brains trust!

    I am trying to figure out how to achieve a particular effect and I'm sure someone here can help me out. 
    In performance I will have a live camera feed set up that plays back to screen also on stage. When someone moves on camera, I want them to appear as a shadow/ silhouette on the screen.
    The screen will also have a still image that the "shadows" are placed into. 
    Theatrically the camera is set on a dinner table with nothing on it. The screen has a dinner table with a full feast on it and I want the audience to become shadows and interact with the imagines feast. 
    Any help would be greatly appreciated!

  • Hey there,

    I don't thinks this will end up being a trivial technical goal if attempted with a typical RGB type camera.
    I would try using a Kinect - but I'm guessing that the resolution of that sensor might not be quite as crisp as you are looking for if the image is going to be made still and put into a frame.
     Something like this is mentioned here: http://troikatronix.com/troikatronixforum/discussion/263/alpha-mask-with-live-video
    There are some fun things you can do combining a Buffer, Difference, and Luma Key actors - however, unless you have significant control over the lighting - such as making sure that the faces of the performers are dark enough that they read black to the camera - along with ensuring that what ever is in the background of the camera image can sort of be mixed into the final composition - you will also need to have the camera locked down with Thor's hammer to insure there no jiggle when folks are moving around as well if the final vid-out is to end up looking like proper shadows and not like ghosts.
    Perhaps you can convince the director and lighting designers to work in a "photo taking moment" in which the lighting of the scene briefly flips into the proper settings for the effect and then drops back into the default look for that scene.
    I've attached a photo and included a link to a short video, showing a quick and dirty version of how you might start playing with the actors I mention above:
    You can ignore the Subtract actor in there.


  • I often use this kinect's with the depth map feed or player index to create live traveling mattes.

    Here are couple of projects.
    Both have samples from how the live silhouetted is used
    I use Touch Designer, but there are other options for sending the kinect video stream to Isadora. Once in isadora you can use add Alpha Channel , Alpha Mask or Matte++,
    The challenge is always in positioning the camera, staging and having right USB extension cables to your computer. 


  • Izzy Guru

    This is quite old now and not the best solution but it may help:

    I tend to use the kinect depth image method these days. 
  • Tech Staff


    What platform are you on?
    The fact that you are looking to work with the audience complicates things since they will likely be harder to light.
    You really need to create a workable contrast between the audience members and the background.

  • Thanks all for your answers! I will have a play and see how it all goes =)