RE: [Visualpython-users] Color / Intensity Question

[David S. <dsc...@vy...>]

> > Background on the first question.  I am looking into doing some 
> > experiments with VPython using digital video output which 
> could have 
> > some applicability to driving a scene projector. I am trying to 
> > understand what data is being generated, how many bits 
> etc., so I can 
> > decide how to encode and grab off from digital video the scene 
> > intensity data.
> 
> Surely this has much more to do with the color depth of your 
> video card 
> than with Visual.

Yes.  Visual uses OpenGL for low-level rendering, and exactly how
rasterization takes place is determined by the OpenGL drivers for your
video card.

Usually, the framebuffer will store 5-8 bits for each of red, green, and
blue.  I have never heard of a framebuffer with a separate intensity
channel.

> > On another related question. How does VPython handle 
> rendering object 
> > data which is sub-pixel?  If I for example have a 
> scene.range of say 
> > 1000 meters, and say 200x200 scene.x and scene.y, then a 
> screen pixel 
> > is on the order of 5 meters. (Math kept simple, in 
> deference to me).  
> > If I have an object that is, say a 1 meter sphere, will it 
> not appear, 
> > or only appear is it happens to be hit by some sampling process?

Again, this might conceivably depend on your OpenGL implementation.
Visual itself makes no attempt to do antialiasing (though it certainly
preserves coordinate information to subpixel accuracy).  However, some
OpenGL implementations can do screen-space antialiasing by
supersampling.

If you want to create very high-quality video from Visual, the best
approach would be to render individual frames at very high resolution
and scale them down (this is essentially a very slow supersampling
implementation).  You will need to extend Visual somehow to try to get
access to the image in the framebuffer.

Alternatively, you might explore using the POVray export to generate a
POV scene for each frame, raytrace it (with as much antialiasing as you
like) and then composite the raytraced images to form a video.

Dave