please help me creating a perforated material!

[blumentopferde]

Hello!

I'm trying to create a material that should look like marble tiles hanging on a metal grid (also see my other thread on marble). unfortunately i'm new to rendering and have some troubles with creating this material, which should be actually composed out of 3 or more materials (see picture).

 

to make it easier and to decrease render time i first tried to create this material without transparency or SSS-materials:

i tried to create the different thicknesses with a flat surface and a displacement map but i had to find out that displacement wouldnt make a solid object but one which is open at one side instead.

i tried to create the hollows with a clip map but failed to create a clip map: even when i used a 2-colored bitmap as tranmittance map i wouldnt get a clipmap but a transparent surface on the white parts instead (if i use the map on an enclosed object). the clip map only worked on a flat object without displacement, if i used displacement at the same time, the clipmap would partly destroy the geometry of the displacemet map, making it impossible to create a clean looking solid.

 

so this raised some questions to me:

1. how do i control a displacement map on an enclosed object? how do i make sure that the displacement only takes place on the desired side of the object and goes into the desired direction?

and how would i make a two sided displacement maps - ensuring that the cylindrical elements really look like cylinders and not like half cylinders?

 

2.how do i create a clip map? and is it possible to use a clipmap on a volumetric object in order to get a perforated object?

 

3. how can i create this material with SSS materials? with 3 different material layers and 3 weight maps? wouldnt that just make 3 materials of the same thickness (instead of different thicknesses, what i want to achieve?). and how can i apply a displacement map on a material which has an invisible material layer? wouldnt that also lead to holes in the object like the combination of a clipmap and a displacement map?

 

4. would it maybe be better to create 2 materials - one for the grid and one for the SSS-material?

 

 

i hope my explanations weren't too confusing and someone can help me to find a solution!

thx!

[Stephen Thomas]

Am I missing something? Why are you trying to do this with materials and displacement instead of just modelling it? Seems like you're going to a lot of unnecessary trouble.

[blumentopferde]

because i already tried to model it. it is quite a big surface resulting in tenthouands of polygons that would not render but crash my computer instead. i was not even able to pan or rotatate the view in wireframe mode with this geometry loaded, neither to export it to maxwell render (even though i have 8 gigs of RAM!) so it obviously HAS to be translated into a material!

[Stephen Thomas]

Not sure about your machine specs but tens of thousands of polys isn't really a big deal. Even a half decent consumer graphics card should deal with that no problem. I just knocked up a 50x50 grid like you described on my home pc and didn't experience any lag. How big is this surface you're trying to make and what exactly is it?

 

Also if ram is your main concern then displacement isn't the way to be going I don't think as that will cause you even more problems.

[blumentopferde]

well, i've tried it (in sketchup and 3dmax), and it didnt work. it will be a facade of an 8 storey building, one element being about 25x25cm large. the building alone, without facade, makes my computer react very slowly, but it is still possible to work with it and to export the scene. importing the facade paralyzes it completely.

(it's a intel dual core processor @ 3Ghz, 1MB cache, 8GB Ram, 1GB Ram on the Graphics card)

 

if you consider that i also want(ed) to have some greenery and furniture in the scene (which doesn't seem to be a good idea, if already this not so very complex geometry fu*** my computer up, i have to save as much geometry as possible!

 

i also cant make the scene much smaller as it should be a wide angle interior rendering from the inner court yard, which reveals the view into the office rooms through glass walls.

 

the marble thing seems to be feasable with a material consisting of 2 SSS-layers (marble white + colored enclosures) and one BSDF layer (invisible material for the gaps). but i simply don't figure out how to use the displacement maps in a way that they would create the desired cylindrical geometry of the metal grid!