using varying res models at varying distance

[Keith W. <kw...@cs...>]

Consider mipmaps for a moment, textures which are downsampled whenever
they are wrapped over objects that are distant from the camera.

I have in mind a similar idea for model geometry.  Any "kind of object"
would have multiple trimesh models that can represent it, with varying
degrees of detail: number of vertices, edges, triangles, etc.  Depending
on the distance an object is from the camera, the program would use the
proper model for that distance and not use the other models for that
object, so very low res models in the distance and high res in the
foreground.

A couple questions.  Is this a novel idea or is there existing research
and work on this idea that I can use as a starting point so that I don't
have to reinvent the wheel?

How exactly is this handled by Quesa, QD3D, and VRAM?  I am unclear on the
distinction between the existence of models in the world, and the action
to submit them to the renderer.  If numerous objects (and their textures)
have been opened from 3DMF files, then are they inherantly taking up VRAM
and other resources (aside from RAM of course) just because they have been
opened?  Or do they not use up rendering resources until I intentionally
"submit" them?

Once submitted, is it just the old LRU internal scheme of the VRAM that
clears them out?  I mean, what happens when the object crosses a distance
threshold and I start using a different model to represent that object?  I
assume the only action I can take in this regard is to start submitting
the other model to the renderer, but what happens under the hood?  The old
model is still there, right?

Or are models never persistantly in VRAM and only textures hang around in
the long term...which would explain why models must be resubmitted for
every single rendering cycle.  I guess I'm not entirely clear on exactly
which things are uploaded persistantly to VRAM until LRU ditches them and
which things are uploaded only for the duration of a single render call
and then are immediately disposed.

Lastly, does my idea sound like a good idea at all, or is it just an
encyclopedia of complexity that basically won't work?

Thanks.

________________________________________________________________________
Keith Wiley                                kw...@cs...
http://www.unm.edu/~keithw                 http://www.mp3.com/KeithWiley

"Yet mark his perfect self-contentment, and hence learn his lesson,
that to be self-contented is to be vile and ignorant, and that to
aspire is better than to be blindly and impotently happy."
                                           --  Edwin A. Abbott, Flatland
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