Using Bump or Displacement to create a scalloped surface.

[gil_peeters]

Hey All,

Pretty new to V-Ray for Sketchup, but wanted to understand how I can create a scalloped surface like the one in the picture:



I used to just model it in Sketchup, but that creates quite a bit of geometry, so I though to do it in v-ray.

I tried creating a greyscale bump map,



but found that the result looks just like 2 wide coloured bands with varying darkness, even if I 'scaled up' the bump intensity..



When I check the v-ray material preview, it looks like the scalloped surface is there, but there also seems to be a flat area between each repeat:



Can anyone give me any pointers? am I on the right track?

Or is there a better way? I have tried displacement too, but that give me stranger results.

Thanks

Gil./

EDIT: I understand the gradient that I used in the greyscale image is not correct, as it does not model the curved bottoms of the scallop profile correctly, but none the less, I want to usderstand why I am getting these lines between the scallops in the render and preview.

[wzfwzfwzf]

Add replacement, see attachment for details

[gil_peeters]

Thhanks for the reply @wzfwzfwzf

I loaded up you file and tried to render it, but did not get the scalloping like you did..

See the attachment for the result I go.. just a flat surface.. Is there another render setting I need to change?

Thanks again.

G./

[gil_peeters]

I noticed that my rendering engine was set to CPU, so I changed t to both CUDA and GPU.. I now get something different.

It looks like the displacement has been applied visually to the surface, but I don't see the displacement on the edges like in, but still not the edges that you show in your screenshot.



I also checked the render settings/switches and Displacement is checked, so it should be working.



Any advice would be appreciated.

[gil_peeters]

Got it working! When I dug into the Displacement element, to the bitmap. It said the bitmap was missing... so I re-loaded my own bitmap in and that fixed it..

Very finicky!



Thanks for the help.

G./

[gil_peeters]

Next question wzfwzfwzf... Is it possible to get the raised edges filled?

I would use this texture on one face of a model that is a 'board' (i.e. a solid 3D group). The displacement sits above the solid. I know I can move it down, which sits it in the solid, but the edges of the solid are square and raise above the grooves in the displacement.

Hope that makes sense?

G./

[wzfwzfwzf]

As far as I know, displacements cannot be stacked or reused. But you can layer bumps to achieve some complex effects.Complex models are best solved by modeling.

[gil_peeters]

Thanks for the reply wzfwzfwzf , but not quiet what I meant..

I'm not at my rendering PC right now... so just marking up your original picture to show you what I meant


Really talking about filling the gaps that that the displacement creates on the edge of the surface.. So the red area is a surface that is at right angles to the surface with the displacement. The side of the panel so to speak.

Can you fill that area that is shaded red, so there is no gap there?

G./

[wzfwzfwzf]

It can also be done by compositing textures. Create a state that needs to be superimposed.

[wzfwzfwzf]

Thanks for the reply wzfwzfwzf , but not quiet what I meant..

I'm not at my rendering PC right now... so just marking up your original picture to show you what I meant


Really talking about filling the gaps that that the displacement creates on the edge of the surface.. So the red area is a surface that is at right angles to the surface with the displacement. The side of the panel so to speak.

Can you fill that area that is shaded red, so there is no gap there?

G./

It is recommended that you model to solve this problem. will be simpler

[wzfwzfwzf]

Thanks for the reply wzfwzfwzf , but not quiet what I meant..

I'm not at my rendering PC right now... so just marking up your original picture to show you what I meant


Really talking about filling the gaps that that the displacement creates on the edge of the surface.. So the red area is a surface that is at right angles to the surface with the displacement. The side of the panel so to speak.

Can you fill that area that is shaded red, so there is no gap there?

G./

You can also use boolean cutting

[gil_peeters]

Wow! Awesome! You are a legend!

Did not even know that existed!

Cheers

G./

[konstantin_chaos]

Hi gil_peeters,

The approach that wzfwzfwzf has suggested can work.
On the other hand the displacement quality you need will lead to slower renders.
If you want to stick with Displacement it would be better to select the 2D mode (procedural textures do not work in this mode).

There are a couple of things I'll say here:

1. Using bump mapping should still be considered as an option, especially if you don't see the surfaces curved edge and if you don't need a closeup

Here I've used a Gradient remapped with a Bezier Curve to procedurally control the curvature.

2. Modelling the actual geometry is also a good idea.
This setup will certainly render faster than Displacement.
If the SketchUp's viewport struggles with the poly count you can always export the object as a Proxy Mesh. A low-poly viewport preview is going to be automatically generated and the full mesh will be loaded render time.


The image on the right shows that the Proxy and the actual mesh render the same way.

3.There is one more V-Ray feature which could help you but it's unfortunately not currently available in V-Ray for SketchUp - Render-time Subdivisions.
It allows you to subdivide and smooth low-poly objects during rendering.

This is not the first time the Render-time Subdividing has came up.
We will consider exposing this feature in the product.

Regards,
Konstantin