Problems about Vray rendering. To creat plants on earth shelter architecture

i have made the shape, like this.

and now i want to apply plant or just grass to coverthe shape.

The problem is that when i apply the grass material on the surface and render it, it become like this.

And the goal i want to reach is that the whole surface is covered by the grass except the window . like this above.
What can i do now?
Please help me~

Pleas share your grass material and I’ll see if I can help

Sorry, there was always an error when uploading the zip file.
I can only paste a link for the material and could you download it.
Any type of grass is ok. I tried all, they al have the some problem.
Thank you very much.

At a glance, those materials seem to be grass textures with displacement.
Your image looks like the displacement (an probably the texture too) is scaled wrong. You need to adjust the texture tiling in order to make scale the grass down to a reasonable size.

There might be other problems in the scene like wrong normal direction of the grass surface.

Hi Lia,
I downloaded one grass material from your link.
In a scene in inches, I applied the material on a surface roughly 240" x 240" and used surface mapping with a UVW repeat of 20-20-1 and got good results.
If your units or scale are different you have to adjust. The displacement is set at 4.5 in the material I used, you should adjust this too.

Might be better if the tiling was smaller, like 10" tiles or so.