P3D Re: 3d shadows in Detroit

[Greg Downing <downing@xxxxxxxxx>]

> When I mentioned that shadows are flat, one
>person said that if the shadows are formed on a 3d object then they
>are not flat.  So I took a picture of my shadow in the steps of
>my workplace as I was desperately looking for pictures in the last 
>minute (as always!).  I ended up reversing the image (R chip to L
>and L to R).  That did not alter the shadow but it did change the
>shape of the steps.  This sufficiently confused the judges to give
>it second place!!!

     OK, I have got to see this example, it sounds very interesting, do 
you have it up on the web anywhere?  I do not understand how a shadow 
behaves differently than say an image painted on the steps. It seems that 
the behavior of parallax would still apply. Are you saying that the 
"head" of your shadow, which is farther away up the steps appears to be 
the same distance as the "foot" of your shadow at the base of the stairs. 
Did you notice a difference when taking a picture of a shadow when the 
light source was not behind the camera. 
     
     I am also interested in seeing a sample of the 3d shadow of a 2d 
image effect you mentioned. I am having trouble visualizing the result, 
does the 3d shadow appear to be in front or behind the 2d image?

     Thanks for the report from the other side of  Alice's Looking Glass.

-Greg


------------------------------