"Reactor" <rea### [at] hotmailcom> wrote:
> "sumdumguy" <nomail@nomail> wrote:
> > I have a scene where only a small part gets changed frame to frame so I want to
> > render the first frame fully and then the following frames only for a selection
> > of rows and columns, automatically keeping the rest of the pixel values
> > unchanged from first frame. How do I do this?
>
> Depending on what changes and what else is in the scene, you could render the
> static background, then render the animated part without anything else around
> and use the alpha channel to composite.  You may also be able to achieve this
> even if there is some degree of scene interaction (such as reflections or cast
> shadows) by using the no_image, no_shadow, and no_reflection modifiers.
>
> Of course, if a 'background' object occludes the animated object at some point,
> it would need to be re-rendered with it and composited also.  Furthermore,
> using radiosity in your scene will depend on the locations of all objects
> present, which means that trying this technique with radiosity will not look
> like it should.  There is also the issue of shadows cast by your object...
>
> Some of the above issues can be worked around by clipping the entire scene into
> a small box that moves with the moving object and having the background alpha'd
> for compositing.  If you lengthen this box along the axis of the camera, toward
> the camera, this could also ease occlusion problems.  It may take some work to
> get such a thing going, you may still save some time.
>
>
> -Reactor

Yeah, I use radiosity and thing occlude each other. But holy jebus, 3.7 is so
fast. Thanks for that suggestion.

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