BUMP materials and losing displacement in the base material...

[Armada01]

I'm trying to create a convincingly looking sea, about 2BF wind.

T

he basic idea is that I'd use a single texture map for three different levels of waves, since waves are essentially built up like fractals, just copying the same structure at different scales.

The highest level of wave (swell), I just model in 3D.

The second level of wave will be created through displacement with the texture map in original size. (this will allow to see some uneven intersection of the water with objects floating in it)

The third level of wave (wavelet) will be created through bump map with the texture map repeated 5-7 times.

The fourth level of wave (mini-wavelets) will also be created through bump map texture, repeated 25-50 times.

The swell is modeled and the base material including second level and third level waves is also done.

Now for the fourt level waves, I'd like to set it up in such a way that the small waves are added as a bump on top of the already created material. I believe the tool for that is "bump material". I could also combine several waves sizes in the texture in Photoshop, but then I wouldn't have the option to change the wave size and spacing anymore. Another disadvantage with this is that the waves are all in a single tiled repeated pattern, while with an additional bump layer (as in the bump material) I could set the spacing to create non recurring patterns.

However, when I make a bump material and select my original material for it's base, the displacement that was there before, is now gone.... Is this a bug??

[Armada01]

Just to explain better, the displacement is gone on the rendered image, (and not in the VRAY UI window, for those who might interpret it this way)

[Armada01]

As an example, below two images,

the left one is the base material with displacement (wave level2) and bump (wave level 3)
the right one is the bump material applied on the base material (showing smaller, level 4 wavelets as well) but the bigger level 2 waves of the displacement are gone...

[Armada01]

Can somebody from chaosgroup have a look into this issue? I don't think its a negligible one!

[palosanto]

First of all: Are you using a mesh or an infinite plane ?
Also, how come you got the first image if it's showing displacement, what did you do different in the second image ? Please clarify or send me a sample and I can take a look.

[Armada01]

I'm using a mesh, because I want to use that geometry to add some swell (first level waves as I call them above). This way I can use the displacement for normal waves (level two), and bumps for level 3 and 4 (wavelets.)

The first image was made with the base material (containing a texture map for displacement as well as bump). That's why you can see the normal (level2) peaky waves and the smaller wavelets on top. The swell is not really noticeable in this view (and not relevant for this topic. It works, since its modeled)

The second image is the base material with another bump on top ("bump material"). In this case you can't see the normal (level 2) waves anymore since the displacement is inactive (but slider is "ON"). However, what IS shown are the wavelets (wave level 3, through bump map in base material) and smaller wavelets (wave level 4 through bump map in bump material). (notice that the first image doesn not have these smaller wavelets. (since its just a base material, not a bump material. so there's only one bump slot to use)

So what I want I to obtain is the combination of those two renders.

Makes sense?

I uploaded a scene file for the chaosgroup support (georgi georgiev) this morning showing the issue.

[palosanto]

The only think I can think of is that you used the same mapping channel for the original displacement as the channel for the second bump. Make sure that each map has its own mapping channel in Rhino ...
In fact you could use two displacements by using a mix map as long as each has its own mapping channel. You don't even need to model the big waves if you don't want to ...

[Armada01]

Ok, thanks for that info. I'm not used to work with channels.

So, I've created 3 texture channels for the sea object in Rhino. all with same UV tiling.

channel 1 - box mapping
channel 2 - box mapping
channel 3 - box mapping

In vray, I assigned for the base material:

- the displacement map to UV channel 1
- the bump map to channel 3

and for the bump material:

- the bump map to channel 2

When I render, the displacement is still inactive.

Have I done something wrong??

[palosanto]

Why box mapping? I use surface or planar and control the tiling in Rhino. Also, try using '2d displacement' instead of the default 'normal dispacement' under Mode/Map
By the way, I hope you have displacement turned on in the geometry general settings and not only in the material itself ?

[Armada01]

Yes, box mapping might be superfluous in the case of a flat surface, I've set it to planar.

All other elements mentioned were set accordingly. Still, the displacement is not working in the bump material. (see below: left square = base material / right square = bump material).

[palosanto]

I can't help you without seeing the material. PM me and I'll take a look.

[georgi.georgiev]

Regarding the issue with the V-Ray Bump material when another material with displacement is slotted in it, please be informed that currently this is not supported since the V-Ray Bump material does not include a displacement node in it.

The dev team are considering a possible solution to implement a material, where the user could create one and choose individually which plugins to be include (displacement, bump, etc)

[Micha]

I'm not sure I fully understand the problem. I did a test - large scale texture for displacement and small scaled texture for bump. Is it the wanted look?

Left: only displacement and Right: disp+bump