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Casting shadows on marker plane

By harism on Thu, 11/15/2012 - 17:37

Hi, another idea I was thinking about is casting shadows on marker plane. This would be a bit more tricky to implement, possibly undoable too, but was thinking about following procedure. It's shadow mapping I was thinking about.

  1. For shadow maps to work one should first render depth map from the light point of view. This is the hardest part AFAIK but might be doable using currently available pose- and projection matrices. This would include rendering both marker plane and 3D object into depth buffer.
  2. Render the scene as usual - with the difference there's shadow map available. For casting shadows properly one should also render the marker plane too on which the shadows are most likely cast.

Will give this a go later on once I have time but leaving the idea here for others to see.

Here's a few "proof-of-concept" pictures rendered with somewhat similar technique as described in previous post.

http://i.imgur.com/VHktK.png

http://i.imgur.com/ZolcO.png

Second image shows situation in which cube is partly occluded by marker plane.

AlessandroB

Fri, 11/16/2012 - 11:32

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Hi, shadow mapping is a very cool thing, especially in the AR case;

I encourage you to explore your ideas, and if you then have any sample code to share, feel free. I'm sure this will be useuful to a lot of other developers.

Hi, I added a video on Youtube showing the shadows using shadow maps (sorry foor poor video quality);

http://www.youtube.com/watch?v=qRAv1FDtJC0

What I learned is that I had false assumptions earlier before I started to implement this.

Thought I'd bump this thread since it seems shaders that allow transparent objects to recieve shadows are much in demand.

Anybody have any pointers as to how this might be achieved?