Guardrail ?

[bla bla 2]

..

[bla bla 2]

Pourquoi, j'ai ce problème ?

Why, I'm this problem ? 

[Oshyan]

Increase Displacement Tolerance in your Planet object. Try 2 or 3. Don't set it much higher than that, it will greatly increase render time.

- Oshyan

[dandelO]

Long, thin displacements, Bastien. Try to increase 'displacement tolerance' in the planet node, although, this doesn't always fix the problem entirely.
What WILL fix it completely is to use only one render thread and set the bucket controls to the same size as your image, uncheck 'allow auto-reduction'. That isn't a very good solution if you use a multicore machine, I know. Instead, you might try to use all your render threads and set the bucket sizes so that they don't cross the tall displacements. That's not very handy for animation, though...

[bobbystahr]

curious how you're going to do the horizontal bar...wouldn't importing a model be easier?

[Dune]

Why don't you experiment with the grass pop. I just did after reading your query, and (until TG crashed) got some nice results. Use a single large blade as object, set spacing variation to zero, and use a distribution shader to cut of if needed (opacity function). Turn blade upside down, restrict rotation to zero, angle it 45 degrees, give it a nice color and reflection, etc.
Only problem if you warp a line of blades their orientation will not follow the warped line.

[bla bla 2]

I can do better ?

[bla bla 2]

I can't do it.   

[fleetwood]

What WILL fix it completely is to use only one render thread and set the bucket controls to the same size as your image, uncheck 'allow auto-reduction'. That isn't a very good solution if you use a multicore machine, I know. Instead, you might try to use all your render threads and set the bucket sizes so that they don't cross the tall displacements. That's not very handy for animation, though...

When I try the one large bucket method the displacements in the render look just fine but in the final second when the render wraps up processing the entire render view will often get reset to all black.

That sort of thing can be annoying  , plus the blackout problem appears to have a random aspect.
Occasionally the very same render will complete normally.
Any suggestions on overcoming that final blackout ?

[dandelO]

Sorry, Fleetwood, I didn't ever experience that problem with a blacked-out render. Actually, thinking about it, this method I posted as working was fine in an older build, maybe around 3-5 years ago when I was having problems with fake grass being chopped at some render buckets, there's probably been some significant changes to the program that bring about this black screen problem since then, I haven't tried it recently. :/
I think, if the tolerance setting in the surface doesn't fix the cut-off issue, you'd maybe be better just using a different default AA level that doesn't cross the displacements, or editing the bucket sizes(probably better) to the same effect. Sorry.

[fleetwood]

Thanks, DandelO
I may test it some more.

[bla bla 2]

J'ai trouver, il faut utiliser le water shader " pour rendre le mur invisible sous le grillage " ensuite ajoutés deux surface layer, un autre de water shader comme pour le premier water shader, ensuite le defaut shader et importé la texture dedans laisser tout par défault et ajouter la caméra. ca fait ce rendu.

Après, je pense qu'il faut ajouté plusieurs default shader et de caméra tout autour du circuit ou à l'intérieur. 

*I translate tomorrow, I do not have time.  Iam sorry.

[bobbystahr]

translation

I find it necessary to use the water shader "to make the invisible wall on the fence" then added two layer surface water shader another as the first water shader, then the default shader and texture imported inside leave all by default and add the camera. it makes this rendering.

After that, I think we added several default shader and camera around the circuit or inside

[Dune]

Probably takes long time to render 

[bla bla 2]

Yes, Dune. 

Thank you, bobbystahr.