From: Paulo Dielli
Are there any tips for better LOD?
This is a design issue: LOD is a fact of the technology used to render objects in three dimensions and sculptors have to take that into account when creating an object.
Of course you are quite right that adjusting the LOD display of your viewer is not an adequate design solution: most residents use the plain vanilla settings that SL sets automatically to match their hardware configuration on installation. It is bad design to assume that a resident will go to the trouble of resetting to an inappropriate LOD display (even if he or she knows how) because a sculpted object looks like crap.
I am still very new to sculpting but I have been working hard to get to grips with LOD. As far as I understand the issue, doubling up vertex points not only creates sharper corners and edges but it also improves LOD since each additional vertex point effectively increases LOD by an extra stage.
The recent implementation of oblong sculpt maps in SL has helped with this issue because they allow greater flexibility in the distribution of vertex points. I believe that only 64 x 64 sculpt maps were useable in viewers prior to the latest release, whereas SL will now accept any permutation of 4 that calculates 1024 pixels (ie: 256 x 4, 128 x 8 ...). Be aware, however, that older versions of the viewer will not render oblong sculpt maps properly, although the problem here is really a matter of choice for residents who insist on using inappropriate hardware and software to render SL.
Apart from that, the designer is obliged to decide the appropriate maximum distance at which the object will be viewed and deal with LOD accordingly. I have just finished a set of windows, which are rendered perfectly as far the graphics card can see, by using quadruples of every slice on the joints, frames and sills. I also finished a faucet for baths and sinks that use only doubles since it is unlikely that the object will be viewed from a distance of no more than several metres within an enclosed space.
In both cases the surface texture was compromised because only a portion of the objects' actual surfaces were being displayed. A 256 x 256 texture would look like a 128 x 128 on the windows, for instance. I got around this by doubling up different versions of the window in the same texture so that two adjacent windows appear to be different even though they are using the same 256 x 256 texture, which was flipped in one case.
Another trick to help cheat LOD is to make the sculpt map significantly smaller than its intended size for final use. This does not always work but it works often enough to make experimentation worth your while. The problem here is that the physics engine will 'see' a much larger object and avatars will accordingly bump off its larger but invisible 'real' size at unusual distances.