Fur strands rendering black

[ana.ramon.michelena]

Hello everyone,

I have a strange thing going on while rendering grass using the Fur tool: the strands always render black, and I don't know how to solve this! I took some screenshots when the problem occured:

- In the beginning of the rendering process, the grass looks fine (image 'fur 1')
- Once it gets into the progressive sampling, the grass turns black (image 'fur 2')
- It stays like this when the render is finished... (image 'fur 3').

I tried changing the material (Vray material, Sketchup material, just a plain color, ...). Only when it has no material applied to it, it renders white (image 'fur 4'), in all other cases: black.

I noticed when I create a fur object in a different file and paste it into my project, this object renders fine, but not always (or only for a while, after a few tries it's black again).
I have had this problem several times over the past weeks with various projects, so it is not linked to this specific Sketchup file.
It also occurs on very small patches of fur, so it's not connected to the size or complexity of the object.


Anyone has an idea how to solve this??

greetings,
Ana

ps: I am using Vray 3.6 for Sketchup 2018

[peerman]

Hi, it looks like the vrf is not showing the rgb color but the diffuse or some other renderchannel. Could you check that? Your screenshots are cut off where the channel info is.
Best,

[konstantin_chaos]

Hi Ana,

There is a known limitation that has to do with Fur rendered by the GPU(Hybrid) engine:
Basically, when the Fur is using the base geometry material and the material itself is applied to the geometry faces it'll be rendered black (by the GPU).
The reason for this is the specific shading network that is auto-generated to account for the way in which SketchUp materials are assigned.

To solve it you can do one of two things:
> Apply the Grass material to the ground geometry group and let the faces use the default SketchUp material.
> Select the Fur in the Asset Editor and enable the Material rollout toggle. Then you can select the desired material from the drop-down menu.

This issue will be resolved in the future.
In the meantime I hope the suggested solutions work for you.

Regards,
Konstantin

[ana.ramon.michelena]

Hi Konstantin and Peerman,

I saw your replies just now. Thanks a lot for your advice, I'll keep it in mind!

@peerman: it was the RGB channel showing in the screenshots

kind regards,
Ana

[kenancakir]

Why are you not deleting the terrain under the stones?

[ana.ramon.michelena]

Because this was an unfinished model, just to show the problem so I could post it on this forum