[feynman]

Anyone had good success with displacement for tufted carpet (2-3cm high strands)?

Problem I have: with adaptive on, displacement looks great but render time goes through the roof. With adaptive off and high subdivisions, it looks totally flat and not displaced at all but it renders fast.

In both cases, a simple 2-triangle plane was used.

[numerobis]

why don't you subdivide the plane?

[feynman]

Ah, so it's the plane needing more polygons in this case, not subdivisions in displacement parameters. The latter I bumped up to 128, 256, 512 to no avail. Will do what you suggest.

why don't you subdivide the plane?

[Mihai]

The more initial polys that displacement has to start subdividing - the less subdivision needed in the displacement component. Try also pretesselated instead of on the fly - it will be faster.

NEVER NEVER NEVER have adaptive on for the final rendering, especially if you use a high rez texture. It will make a lot slower render as it's subdiving until it gets the detail from each pixel in the displacement map.

[feynman]

Thanks, yes, as you previously explained, that's what I do. Pretessellated is faster, I see. Got 16GB ram on nodes. Only thing was that I kept the 2-poly plane instead of using a higher subdivision, so there was nothing for the displacement map subdivision to work on, so to speak.

[feynman]

Blimey, the subdivided plane (8x8 on the right) turns out rather like a cheap-o beer mat, whereas the other (wrong, slow 2x2 plane on the left) comes across well shaggy ;) I still don't seem to get it, although I read the manual.

[polynurb]

considering 1:1 scale, try something like 1 poly per "thread".
so if you render a 1m² give it ~1mega polys; sure that is quite high but it will render much faster although it will take longer to load at rendertime... you will have to experiment with your texture, you'll be able to go much lower most probably, depending on how close you move the cam.

for the extra bit of control you can also try to match up the pixel dimension with the subdivisions, 1:1 or 2:1,4:1 etc..., so that you get a even relation of subs vs. pixel across the plane.

[feynman]

Thanks, I try that. RAM is plenty.

[dmeyer]

Why not use fur?

[feynman]

I'd absolutistically LURVE to use fur, etc. - but Alias, Pro/E, MATLAB, etc. don't have hair, particles and other niceties :( so, I have to shag on displaced fibres :D

[feynman]

Flat like the Earth - now with 0,5 million triangles and max. subdivision (10000) in material editor :( looks like displacement only works predictably (height, texture fidelity, visual impression) with on the fly and adaptive settings...

ps: alternative solution - does someone know of some good quality carpet OBJs one can buy and then texture and render in Maxwell Render withouth the need for an intermediary software? Only found C4D, 3DS, etc. stuff...

[oz42]

just a guess but have you tried maxwell grass?

[feynman]

Hehehe - would have liked to, if it is now crash-free, but - because in 2.7.1 resuming cooperative renderings is broken (in my case), I just have to downgrade all PCs to 2.6. So, no grass for me - yet.

[Bubbaloo]

My 2 cents:

Like attempting displaced grass, I think displaced carpet will fail to look realistic, especially if it'll be seen up close. A hair system, with some SSS is really the only option in my opinion.

[feynman]

Well, the one on the left, higher up in a previous post, was going to look alright, but it was done with adaptive on the fly rendering which is abyssmally slow. Because I got no hairy software, that's my only option, or I buy some 3D rags, if only I could find some I could whack into Studio. But, still, displacement with pretessellated and high subdivisions should work in any case, but isn't, no matter how many millions of polygons I use. Always looks flat like a beer mat.

Don't you have some dirty old OBJ carpets (3x2 metres rectangular and 3x3 metres circular) laying around in your attic? I could send my janitor to dust 'em off and pick 'em up...

So, found OBJ carpets for $ 60 each. Not so nice, but what can one do.