Getting Started - How do I use Effects with Motion Capture?



  • Hello,

    My name is Jesse. I am a current BFA Lighting Design student at the University of Florida. We are currently working on a dance production for our spring semester. I am hoping someone will be able to lead me into the right direction on how to properly use the Isadora software, and to find out what other materials I will need to pull off the desired effect we are trying to achieve.
    We are hoping to have a dancer interact with a projection on the floor. We want the projection to resemble a body of water and as the dancers move around the stage to cause ripples behind them. I have watched all of several tutorials on youtube but I’m still confused on how to accomplish this effect. If you could assist in anyway it would be greatly appreciated.

    Sincerely,
    Jesse


  • Tech Staff

    Hi,

    The first issue you are likely to encounter is video feedback. If you have a projector pointing and the floor and presumably a camera to track the dancer pointing toward the floor then the camera and software will see all movement.
    And since all the software see's is pixels it can't work out which one is the human. So you may need to think about InfraRed lighting and InfraRed cameras.
    To create the water effect is quite hard; i've never done it. Off the top of my head I would look at the displace actor and maybe the shimmer effect. The displace actor might have to be mixed with a large image of water created in photoshop or similar. I'm sure some other users can help with this too, or have an other idea (there are probably many ways).
    But the area I do know about is the actual motion tracking. You need to use eyes actor and track the movement. I have some tutorials on my blog.
    http://vjskulpture.wordpress.com/category/isadora-tutorials/
    http://vjskulpture.wordpress.com/2011/02/09/basic-motion-tracking/
    http://vjskulpture.wordpress.com/2011/02/13/the-problems-with-motion-tracking/
    This will get you going for now.


  • Hey,

    Thank you so much! That was a great help to get me going. I have been running into the problem with my camera also picking up the projections. Is their a specific kind of InfraRed camera you would recommend getting?

    Thanks so much,

    Jesse



  • I would seriously consider using a Kinect for the tracking as long as the range limitations work out. All the tracking work has already been done for us with the Kinect so you are going to have a much easier time than with an IR camera and illuminators.


  • Tech Staff

    Matthew is one step ahead of me! The best and most affordable method is indeed the kinect camera. It solves 99% of your problems. Where you position it for distance it's and angle need consideration though.



  • Hi Jesse,

    I tried to figure out how to create artificial water ripples. attached is the result. The comment are n dutch, but i guess it's all rather self-explanatory. It's based on overlapping blurred ovals that form the input of a displace actor. You can use a tracker to manipulate the zoomer values
    Maybe it can be of some help for you.

    Best wishes,
    Hans
    9acdc0-waterreflectie.izz



  • Jesse wrote me through the support form, and this was my response.

    ---------
    Dear Jesse,

    Well, this kind of interactive water effect has mostly been accomplished by some of the top practitioners in the field -- and usually because they can write their own C or C++ code. It is not an effect that is built in to Isadora -- especially if you wish to make it look super real.

    But, one effect you can play with is the Displace actor. Put your video source into the top input. Then, in the second input, add a video that simulates some ripples. Try using the attached movie, called drops-center.mov to get started. The brightness of the second image "displaces" the first, simulating the water drop effect. The idea would be to have multiples of this movie -- or something like it -- combined with the MultiMix actor and fed into the second input of Displace at the same time.

    Perhaps you can invent other ways to use the movements of the dancer to cause this to happen. You should investigate the Difference actor for example.

    Then there is the issue of tracking the position of the dancer, so that he/she can influence the image. This is also requires some special lighting and hardware. This is also pretty sophisticated stuff if you've never done it before. It requires flooding the space with infra-red light and using an infra-red sensitive camera -- along with a technique called "background subtraction" to find the position of the dancer. Unfortunately, this is simply too complex for me to help you with here.

    Do search the TroikaTronix forum at http://troikatronix.com/troikatronixforum/ as well as the old forum archive at http://forum.troikatronix.com/ -- there you should find some more information about IR tracking.

    And, for any continued discussion on this topic, please join the new forum and post your questions there. Then, when your questions are answered, everyone in the community benefits. OK?

    Best Wishes,
    Mark

    20a128-drops-center.mov.zip



  • Hello Everyone,

    I can't thank you enough for your help and suggestions. They have been such a great help in leading us in the right direction! I'll be sure to post our results on the forums!

    Sincerely,
    Jesse



  • Here is something I found when looking for the same kind of thing. It is the basic concept of water ripples over an image. It is for OSX and now is standalone. You can move the water with the mouse. I can hook this up to syphon and osc if you are interested in using it (you can send the background a stream over syphon and send the coordinates of the displacement via osc.

    Fred

    54d615-water-example.zip


  • Tech Staff

    @Fred

    Just wanted to say thank you for sharing your time intense researches and coding skills.

    Best,
    Michel


  • Tech Staff

    That's great @Fred.

    Thanks for sharing.

  • Tech Staff

    sounds fun.. never for windows though.



  • @hanslas
    Wow, I would never have tried to do that in izzy but you made a pretty fine attempt at water there!! Where in the Netherlands are you?


  • Tech Staff

    @hanslas
    thats true what Fred says, and for jessefryery if you conect the stage mouse watcher to the shapes horz and vert position, limit their input to -50 and +50 you can position the center of the ripple via mouse.

    Best,
    Michel



  • @Fred, thank you for sharing, that's great,
    did you do it on Processing, or?



  • I made this with openframeworks.



  • @Fred, your proposition of hooking up to syphon and osc your water-moves is great, could you do it please?



  • I will try to find the time, I am super busy with a show at the moment. It will take a bit of your juice though, check what resolution you can send and recieve over syphon while keeping the rest of your system going. I may get a chance to look at this mid to late next week.

    Fred


  • @Fred, thanks, that looks promising, I'm using syphon fine in different resolutions (but I'm sending max 720 vertical to projectors) with processing and QC, using osculator with wii and kinect, never used openframeworks...



  • @Fred, I fund out that there are 3 lines for Syphon implementation in openframeworks, if you like I could get it to you, or if you would send your patch, I have someone that could implement the syphon in your patch, we are still in research mode for openframework osc in Mac


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