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Old 13th September 2008, 12:58 AM   #1
ahkenatan
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Default Anyone know what I am doing wrong?

I've been noticing this happening to my sculpted prims lately. I think it may have some thing to do with stitching but I tried all the different options and it goes from bad to worse. Maybe I am not saving the sculpt correctly in ac3d or is it a setting?
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Old 15th September 2008, 09:36 PM   #2
lisa
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Default Re: Anyone know what I am doing wrong?

I know what's going wrong... I'm trying to get some help from LL on a fix, or come up with a work around myself. I just recently ran into this myself and it took me a long time staring at it in wireframe (control-shift-d in the viewer, I think) to figure it out.

Here's the problem: video cards force textures to be square powers of two. i.e 8x8, 16x16, 32x32, 64x64, etc. Sculpt maps, being textures must thus also be square powers of two.

For reasons inexplicable, Qarl Linden made the mesh for planar sculpted prims 32x32 *surfaces* instead of 32x32 *vertices* -- his mesh is 33x33 vertices!! Ouch. This means, no matter what you do, you *can't* get a 1:1 of vertices to texture even with a perfect texture. What he *should* have done is made the mesh 32x32 vertices, 31x31 surfaces.

Now in truth, I can theorize as to why this was done. I am assuming Linden Labs did it this way for LOD reasons. There's a way to do an edge collapse that used to be quite common in games and such from a few years ago. In fact, if you've ever played Motocross Madness 2 or any of the Rainbow Studios games, they use the same algo for decimating the terrain mesh. I'm assuming Linden Labs is using this method for generating LODs, and that method needs a 33x33 mesh to work. The *right* answer is to use a different method for reducing the mesh--I'd recommend edge collapse based on angle and discontinuities myself, you could potentially save many more polys that way--but that's a lot of work, so I'm assuming that's not going to happen anytime soon unless I do it myself. Sigh.

Anyhooo... to cut to the chase, if you resample your sculpt map much larger, when SL re-samples it back down, you can get it to fill in the missing vertex. Resize your map in photoshop and double or triple the pixels *without* any anti-aliasing on the resize. That should get rid of the gap.

At the worst case, I'm going to put an option in the next version of the exporter to do this, but again, hopefully someone will fix the viewer first! I think there's a JIRA entry for this already, but I can't remember what the number is.
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Old 15th September 2008, 09:37 PM   #3
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Default Re: Anyone know what I am doing wrong?

Oh... BTW... your model is looking stellar. That's a beautiful car. Did you make the one in the background, too?
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Old 16th September 2008, 07:56 PM   #4
ahkenatan
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Default Re: Anyone know what I am doing wrong?

Thank you very much Lisa, I'm starting to understand how it works. I'll try that it makes sense actually.

Thank you for the compliments

I posted that car and another one in another thread a moment ago.

http://www.inivis.com/forum/showthre...3418#post23418
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Old 18th September 2008, 10:49 PM   #5
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Default Re: Anyone know what I am doing wrong?

Well, I tried to resample the image in paintshop pro tried 128x128 and 192x192 and I still get the dreaded gap. I didn't see anywhere where I could save it without antialiasing so maybe thats the issue.
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Old 19th September 2008, 05:04 PM   #6
lisa
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Default Re: Anyone know what I am doing wrong?

In the resize dialog, where it says "resample image" uncheck the checkbox or try switching it to "Nearest Neighbor". I think that should do it. (I use Corel myself, and Corel calls it anti-alias, but Photoshops' resample should be the same thing.)

Also, try sticking to square powers of two, as SL always resamples anything that isn't a power-of-two. Instead of 192x192, go up to 256x256.
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Old 20th September 2008, 03:13 AM   #7
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Default Re: Anyone know what I am doing wrong?

Awesome work, ahken. It's impressive that you managed to avoid wrinkling.
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Old 23rd September 2008, 10:51 AM   #8
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Default Re: Anyone know what I am doing wrong?

Thank you!

I tried to resample the size as many ways as I could but still get the same thing. I do find that when I choose torus for stitching that the gap seems to correct itself but it depends on the shape of the sculpty. It may cause an entirely different problem like a gap in another portion of the sculpty or a weird parts of the scuplty stretched out. Not a big deal I can live with it.

Some of my sculpties do wrinkle. I have pretty much figured out how to avoid it but I also know how to hide it if need be.

The Mercury is finished, I'll post pics when I get a chance.
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