OTOY Forums

does anybody know if it is possible to create a vlevet like material like the one in luxrender? ideally in a material-creation-for-dummies style ;)

it's the one i miss most since changing from luxrender to octane, because it is useful for a broad range of textiles - not only real velvet stuff. applied at decent ammounts, it gives some nice fabric touch to almost anything that should look like cloth...

can't be done for now, hopefully soon we'll have some glancing angle ramp map or something

Proupin wrote:can't be done for now, hopefully soon we'll have some glancing angle ramp map or something

Hmm, I'm sure there are parameters that can simulate velvet etc. materials without going biased.

I'm holding a piece of black velvet and a flashlight right now
In my opinion parameters missing to make velvet are:
- light retroreflectance ratio (wikipedia Retroreflector), which would be invaluable (rarely though) as if I'm not mistaking nothing really simulates that in the industry, yet principle is simple.
- tangential reflection ratio - tendency of light to change direction and scatter parallel to the surface, instead of bouncing away as a diffused or glossy. This would simulate multiple inter-reflections of strands of micro-fuzzy surfaces as velvet.
- inclination of plane that is considered parallel to surface in parameter above, as "fuzziness" usually is not really perpendicular to surface. But I guess this one will require interaction with UVs, same as anisotropy, which I don't know if is possible, but would be nice for many other materials.
Mixing such material with simple diffuse should give velvet... Except it would be too smooth if we zoom in. Real velvet has tiny glossy flakes.

err.. ok, that's too complicated. How about those ramps or something?

Oren-Nayer-Blinn or something down that road, try fake that first off.
The shaders in octane needs some dev..

kivig wrote: err.. ok, that's too complicated. How about those ramps or something?

hahaha... we can go scientific in that ass if you want, but I still don't know what "going biased" means to you... To me, unbiased rendering it's just the progressive refinement of a render. Direct Lighting in that respect IS unbiased since you just leave it there and it will converge to the same result, every time (wikipedia seems to agree). Everything in 3D is an aproximation of nature, a model. Newtonian physics are a rough estimation as well. You don't want to go quantuum physics I think.
Meaning, everything is useful in order to make believable stuff, as gk mentioned, oren-nayar, the ramp map with glancing angles, anisotropy, and the three things you mention, bla, since they're just fine to represent many stuffs seen in nature.

All this stuff has already been covered (asked for) in the thread about new node features. A camera viewing vector + light direction vector + some vector math + ability to influence texture data based on those calculations and we could create not only velvet, but all sort of funky shaders.

I'm waiting for those nodes very much a lot, yes.