mi_bump_flakes tile tile tile and more !

[Dariusz]

Heya

I've been seeing it from years but never actually bother to write and ask for fix. I decided that today is the day !

Can this be finnaly fixed please?

Also how do I connect mi_bump_flake to arch and design material standard bump or overall bump dont work. I dont get any effect if I connect it to mental ray bump slot...
flakes.jpg

Thanks, bye.

[Remydrh]

Can you be a tad more specific? The image is small so not sure what you mean.

[Dariusz]

Heya

Sure here u go. Massive tilling everywhere...
flakess.jpg

[Dariusz]

Up - message too short =D

[wizlon]

Yup. Same problem here. Though not always noticeable.

[bart]

There are two issues brought up here, how to connect, and the tiling artifact.

How to connect.
The mi_bump_flakes shader modifies the normal AND returns a color that is the intensity of the flake. So the bump mode if using mia_material_x has to be the original mr mode that assumes the shader modifies the normal. From the Architectural shader doc, "The bump parameter accepts a shader that perturbs the normal for bump mapping. This parameter is only used if the new bump_mode parameter is zero." Further in that doc, "The shaders put into overall_bump or standard_bump should return a vector, but it is also legal for those shaders to modify the normal vector themselves and return (0,0,0)." But mi_bump_flakes returns a color intensity, ie, not (0,0,0), so if you tried to use standard or overall bump as your input for a bump, then that would affect the normal, depending on mode selected, in addition to the normal modified by the shader.

So any reason you cannot put it into the bump input with bump mode set to 0?

Regarding the tiling, we'll look into that a bit more. Got a simple scene that created your example above? Please list your Density, Strength and Scale values.

[Dariusz]

Heya

Just got to PC at work so havent had time to test it out yet - will do thanks very much !

As to example, sure I can get u one where you want me to send it ?

Thanks, bye.

[bart]

If it is too big to post here, or unable to publicly post, you can send me a message on the forum, and then I'll send you my email.

When incredibly small values for scale are used, when I try to recreate it, I see something a little similar. Not as obvious as yours. So I need a better example.

[Dariusz]

Hello

Right I got a min to get u the test sample. As you can see at 0.001 the tiles explode and are all over the place. Its something that stops me from using this shader in real production making it a bit useless... Also the 0.001 limit is too high. I should be able to go to 0.000001 in size of flakes or even more. If you take a image that is 6/10k big and is a macro shot of car detail, only imagine how insanely big flakes will be with 0.001 and tile issues.

I'm attaching scene and screenshot... Hope we can sort it out :]

[ATTACH]3315[/ATTACH]untitled.jpg

[bart]

Thanks. There's no 0.001 limit, if you are talking about the scale input. That is the Maya UI hiding to 3 significant digits. I got to 0.000000001 before it actually gave out on me, with 9 0s after the decimal point before the 1. I don't get the noise pattern you show above, but I do see tiling and a clear tile edge example when 0.0000001.

When using small scales, keep this doc note in mind, though it is unrelated to tile issue: "Since flakes are inherently small, they can easily introduce rendering artifacts if their visual density becomes significantly smaller than a pixel. To avoid this the parameter flake_decay exists. It sets a distance at which the influence of flakes fade out. A value of 0.0 disables fading. Any positive value causes the flake_weight to be modulated such that it reaches zero at this distance."

Also the strength range is typically only up to 1.0.

In addition, with unified sampling approach, no need to put your samples so high (64) on an area light.