Effect of Texture Resolution on Sculptie Lumpiness

For anyone who have been struggling with trying to achieve smoother sculpties, increasing the resolution of the exported sculptie texture may help.

See enclosed screenshot for a comparison between the recommended texture size of 64x64 and 512x512, 1024x1024.

Until the day SL provides an uncompressed 32x32 texture format for use on sculpties, I will keep using 1024x1024s.

Now the question is: Is the 'bumpiness' caused by the automatic JPEG2000 conversion in SL, or the way the sculptmap is 'sampled' to produce the polygon mesh in SL?

If the former is the case, I think it would be smart if LL would disable any compression on the JPEG2000 conversion for textures <128x128 for instance. The gain here is minimal as it is, and it would solve a lot of issues.

As the situation is, the fact people will go to 1024x1204 compressed instead of 64x64 uncompressed, LL is basically shooting themselves in the foot by using compression.

The texture compression guy at LL must be away on his holidays. I'm sure he'll toggle the necessary setting when he gets back.

The problem is twofold.

I think the MEL script used in Maya sort of samples the model like a sock wrapped around the mesh. Naturally, we end up with just an approximation of the model with lots of unneeded polys in places such as on purely flat surfaces. A different script which will read an object vertice by vertice from Maya that corresponds exactly to the one in SL is whats needed, so that we can have precise control over where to put each vertex. Nevermind that its 32x32. We can always hide the unneeded polys in some corner somewhere.

A further option is also needed for those who want the sculptie to be either flat shaded or smooth shaded (as we have now). People who want to make boxy single prim objects wouldn't want the smooth shading really.

And of course, the JPEG compression artifacts are very pronounced to the point that the most you'd get out of a sculptie with 64x64 dimensions texture is very turdlike in appearance.

Are you scaling down from the 1024 x 1024 to the 64 x 64? If so experiment with the interpolation type. Unlike normal textures where more interpolation is better (eg cubic) with sculpties, this can introduce bumpiness. I did an experiment with None, Linear and Cubic interpolation when scaling from a 256 x 256 to a 64 x 64 and found that NONE gave the best results.

I bake the sculptie straight to 64 x 64 now and get results like the attached..

AAARGH

*commits suicide*

Sorry, there no such thing as a single vertice. AAAARGH

*commits suicide*

AAAAARGH!!

I got another headache!!

Just be aware, everyone, that the same rules apply to sculpt maps that apply to any other texture in terms of size vs. performance. Use too may large sculpt maps, and you will slow people down. Proceed with caution and consideration.

I for one am looking forward to the flood of tables comprised of 5 sculpties with 1024x1024 for each prim. Lag city, here we come!

ADDITION: oo, and I forgot about the visible texture maps. That's up to 10 1024x1024 images for a single table. Rock on!

[/sarcasm]

again - before anyone gets too excited about all this:

(1) shortly we'll be reducing loss in our jpeg compression for sculpt maps.

(2) we'll disallow sculpt maps of large size.



K.

party pooper

*sniff*

Making it 1024x1024 is ridiculous.

The code in the SL viewer samples in a 100% predictable way. Hence you know in advance which pixels will be used for the sampling. Please read the related info in the Wiki. If you scale up from 32x32 wisely you should have no artifacts at 128x128.

Thanks for the update, Qarl!

Yay!

lol sl never changes....
-LW

My understanding is that all SL textures are compressed using JPEG2000. JPEG2000 supports no-loss compression.

Instead of "reducing loss" can you change it so that there is *no* loss? There are several applications of sculpties where modellers require high-precision sculpt-maps, and getting screwed over by compression is not a good solution.

How hard can this possibly be to implement?

if ( uploaded texture <= 64x64 )
......encode using lossless jpeg2k
else
......encode as usual

This way, everybody wins

Yay!

Actually, I get very little to no distortion with 64x64 now, but I also keep in mind the limitations of the mesh. I've learned how to get the edges and such without them dying on the LOD.

hey folks - look at your sculptie with control shift r - they don't have that many vertices, and you're going to get distortion if you stretch one sculpt prim beyond its capabilities.

Make that <= 32x32. As the sampling doesn't use any of the additional pixels in a 64x64 (barring the fact that there's currently a bug for the last line of a 32x32; but that's easily fixable)

Not sure about the bug you're referring to, but the post here:

/8/d2/186099/1.html#post1522861

indicates that a 64x64 texture has 33 lines with data in them. Two with endpoints and 31 with row data.

I don't know why it is that way, but you can't fit 33 lines of data in a 32x32 texture.

From this perspective, it would seem that either we need to redefine sculpties to work in 32 lines of data or we need to make the cutoff at 64x64.

Damn, and I was just about to make Rodents of unusual size.

cutoff at 128x128
we need flexiblity. And honestly do you really want massive textures.