Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Tue, 21 Jan 1997 18:55:33 +0000
You could consider buying the extra TRAM but this may not help much if
you really have high resolution imagery.
You could try using a tlut to use 8 bit immagery to give a colour
representation but this suffers from some interpolation problems.
You could also try using MORE textures. How can this help? I
expect you are asking.
Well you can have your database with high resolution immagery on
the high Level of detail. You then have lower resolution immagery
on the lower LODs, this means that as you fly around the database
the graphics system won't have to page as much information every frame.
Currently it will be loading all the visible texture immagery at highest
resolution (and possibly with MIP maps), most of this you don't need. So
by using the model LODs to reduce the ground resolution in the distance
you will dramatically cut the download requirement probably without
affecting image quality even though it will require more texture data.
Cheers,
Angus.
On Jan 21, 6:28pm, Luigi Rella wrote:
> Subject: Large Digital Terrain Management
> How can I build a large textured digital terrain model to improve performance
> of my machine?
>
> I have a large digital model highly detailed.
> Presently I build the terrain dividing it in N x M sub-models grid (like a
> chessboard) and attach each sub-model under a matrix of pfSCS.
>
> ---------------------------------
> | | | | |
> | | | | |
> ---------------------------------
> | | | | |
> | | | | |
> ---------------------------------
> | | | | |
> | | | | |
> ---------------------------------
>
> Starting from a sub-model I obtain two new less-detailed sub-models through
> sub-sampling of the original one. These three sub-models then are attached
to
> a pfLOD that manages the long distance parts of the terrain.
>
> pfSCS
> |
> -------------- pfLOD ------------
> | | |
> | | |
> sub-model i sub-model i sub-model i
> (low detail) (medium detail) (high detail)
>
>
> On each sub-model (at all resolution), I apply a satellite image of the
terrain
> as a texture.
>
> Without textures I have a frame rate of 15 Hz and the navigation is quite
good.
> But when I apply the textures I obtain very poor performance.
>
> Someone have suggestion to improve the performance?
> Can I build the model in a different way?
> How can I manage the texture to have the low occupation of TRAM?
>
> Thank in advance.
>
> I'm running pf2.1 on a Indigo2 with R10K, Irix 6.2, 1 TRAM , 128MB RAM.
>-- End of excerpt from Luigi Rella
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