Using white noise technique to blur sharp voronoi regions?

[melvi]

In the comment section of this vid:

Avoid Texture Repetition on Large Scale Textures (Blender Tutorial)

Someone mentioned:
‘’ use the white noise technique to blur out those sharp voronoi regions’’

Anyone know how this can be done?

[Secrop]

The technique is basically adding noise to the coordinate system.

white noise → subtract 0.5 → scale → add to coordinates → voronoi

Thought we now have smooth voronoi…

[melvi]

Thanks. I am not really familiar with voronoi myself. Maybe they have added it. I am not sure.

[Secrop]

But after looking at the video… the smooth voronoi won’t work very well when used on coordinates or, as in the video, as rotations… (it will distort and stretch the resulting texture near the edges).
The white noise should handle that a bit better.

[melvi]

Any chance you can pls post a screenshot of the material setup? This is what I came up with based on your post:

[Secrop]

[edit]: forgot to add the white noise to the coordinates…

[melvi]

Thanks man

[Zebrahead]

Not what you asked for (because already answered by @Secrop) but if you’re going to use this technique with a normal map you have to make sure to also adjust the normal map itself before feeding it into the Normal Map node.
Simple example with a sphere as the normal map:

Left plane is using the UVs as is. Middle one with rotated UVs in the Shader. Right one with rotated UVs in the shader and updated normal map.
As you can see, the reflections on the middle one are rotated by 180° (which is not what you would want here). To not break the Normals we also have to rotate the Vector from the UV Map itself by the same amount (but in the inverted direction).
Here’s a little explanation video on that topic: How To Rotate A Normal Map Correctly (Blender Tutorial, Textures) - YouTube

[melvi]

Thanks mate

[CarlG]

@Secrop

The white noise should handle that a bit better.

Used with bump or especially microdisplacement, sounds like asking for problems. Here is the method I prefer to use, with its own set of drawbacks:

You don’t get infinite number of rotations, you only get four. But you do them outside the node group and feed the various orientations into the color slots, which outputs a noise blend of the four inputs. Avoid the problems caused by scrambling the coordinate system completely, incl the increase in information density - which can be extremely visible - in the “blurred edges” approach.

@Secrop

Thought we now have smooth voronoi…

As you said, don’t work for manipulating coordinates. But also, smooth voronoi can be horribly expensive.

[Secrop]

@CarlG

Used with bump or especially microdisplacement, sounds like asking for problems.

For sure… It has been years, since I’ve stopped using this method. But that was the OP’s question. (and I don’t even mentioned how wrong it is to plug the white noise/voronoi color as a rotation of an UVmap, without at least any corrections and constrains over the angles).

@CarlG

But also, smooth voronoi can be horribly expensive.

Ditto

[melvi]

@CarlG

Used with bump or especially microdisplacement, sounds like asking for problems. Here is the method I prefer to use, with its own set of drawbacks:

Any chance you can pls share the blend file with the setup?

What are the drawbacks?

[CarlG]

I could, but where’s the learning in that?
Drawbacks are that there are only four position/rotation/scale variants that are smoothly blended instead of pretty much infinite that are sharply blended, and I don’t attempt to correct for normal maps if used in combination with box mapping or (manual) triplanar mapping. If normal maps depict randomness, I’m guessing it also comes with a bump map style alternative, which works just fine. If they don’t depict randomness, you can’t really blend like this anyway.

Applies to any kind of blending, but if the texture has a strong directional component (like direction of wood grains), you can’t put much into rotation, but offset and scale/mirroring should work ok.