I can not seem to get rid of these black blotchy spots. It only seems to occur on the downward slopes of the grass plane. My topology is correct, all quads. And all verts are welded. My normals all appear to be pointing correctly
IradianceMap/LC
Adaptive Sub -1 2
Using VraDisplacementMod on the grass plane
3d mapping
Edge Length 1.5
Increasing edge legth helps some but makes the grass more patchy of course. Reducing edge legth doesnt help as well.
Any ideas?
2d mapping doesn’t solve it?
Lele
You know I tried 2d mapping, but all I get is a flat colored plane from my material.
I tried to increase my speckle tileing incase it was out of range but nope. I increased the Amount by a drastic amount and nothing.
I might have to just use a displacement map instead(assuming that works), though was hoping i could set different edge length parameters for my grass apart from my other displaced objects
Looks like an UVW issue, if you want to use 2D with the speckle you’ll need to switch the map to explicit mapping to flatten it.
2d mapping helps a bit. Explicit mapping helped certainly, but the look does not appear as nice as the 3d mapping. Increasing/decreasing precision seems to have no effect
3d displacement with new mapping. Was using a completly horizontal planar map before. Cylindrical mapping doesnt seem to help. Also tried a few of the other typs of mapping.
I think it will be your mesh. is it meshsmoothed? if so what does it look like unsmoothed? And try rendering without it being meshsmoothed
It is not meshsmoothed. I tried using meshsmooth, and it does create some better results, though lots of the patterning as you see, plus polycount is undesireable. I also tried it with tessellate. I tried triangle with tessellate for the heck of it though know its undesireable for proper displacement.
As well I have created a new/more simplified mesh from scratch and am finding similar results on the downward curved areas.
Have a quick glance at this thread.
http://www.chaosgroup.com/forum/phpBB2/viewtopic.php?t=14300
May have some tips. I still think its a mesh issue. As long as your mapping is ok.. and changing that doesnt change anything then it will be a mesh problem. You could try overlay a plane with enough segments, then delete the polys that you dont need and move the others into place trying to keep the polys as square as possible.
Would you like to upload just that small part of the scene for one of us to look at?
https://sneakybiscuit.sslpowered.com/matanabel.com/img/grass\_insleight.max
I really appreciate it. I have also tried using a regular displacement map instead of the vray modifier to no avail.
Having a look now.
The main problem i saw with that file was the texture repeating.
Try using a more varied texture or even a grass texture for displacement. I can provide you with a link to my grass pack if you want.. plenty of good texture maps in there.
Also What i tried was a plane with highish segments then moved the verts down to match the grass (or you could use conform.. I tried that.. seemed to work ok) then build 4 seperate grass areas, instead of one big piece of mesh which has other stuff attached to it.
Thanks a lot DaForce.
Yeah it appears to be a geometry issue, though I have not yet tried some less tiley maps.
I found that conform script and it rocks. It helped but there were still some black spots remaining.
ty again. I might have to try vrayfur to get what I am looking for.
The conform I was talking about was the conform compound object. Found in the same place as boolean. Is that the one that you are talking about? Probabaly works similar to what you found anyway.
I will have a better look when i get home in an hour or so. When i was looking before it was theu VNC and that was abit painfull.
Will be able to sort something out for sure 
Actually I think your mesh is fine.
Try this. Ditch your current UVW map and put a planar uvw map on there.. then ditch the speckle map and just for testing use a checker map and set tiling to 50/50 also turn the blur off in the checker map.
You will see fairly nice even displaced checkers.
If you look in the material preview for the speckle you can quite clearly see the patterning in there thats causing it to look crappy.
I will PM you the link to my grass texture there try using one of those for the displacement. Or something other than speckle.. or maybe try to break it up abit with a noise mix map or something.
Im realizing as you said its all in the mapping.
Heres an update. Im getting closer. It is still one mesh and I have been manipulating the geometry independantly in UnwrapUVW, relaxing/scaling/etc. I am using one of your displacement maps(thanks!). What helped the most was brightening up the darkest areas of the displacement map over 128 value in photoshop. The map range is now 128-255 and I saw a significant improvement after that.
I never would have thought that slopeing geometry would be that much more difficult to tweak than completely flat geometry.
Now its super tweaking mode and getting some nice color/height variations.
Looking better
You could always mix a few displacement maps together in a mix map. That could help breakup the even look to it all.
Hi,
I’ve found this thread about 2 days ago, and ever since I read through it about 5 times and still can’t fix my stupid grass issues. Actually the problems are similar but based on this thread recommendation(s), it still doesn’t go away.
I have a very simple scene, it’s just a flat plane equally divided in all directions. In this first image, the YELLOW squares are the grass. It’s one single plane object (with some square polys removed). The RED squares is also a plane object. That is the ground. So I have 2 SEPARATE meshes. Yellow (grass) and red (ground). I have a planar UVW mod applied to the grass:
When I render, I get this:
Notice that on the right lower side stripe, it seems to have a repeating pattern. That is the odd phenomena. The actual grass AND grass displacement textures are repeating 4 times on this whole mesh. So the obvious question would be why is it seem to be repeating only there, but it’s ok anywhere else? Before you try to answer, let me just rotate the view around a little, like on this image below. Now, the repeating seems to be wondered off to a different location. Now it seems to be repeating even more and even on places where it was fine before (compare it with the image above).
This is my grass texture.
This is my grass displacement texture.
In case you wonder, I’ve tried to use bigger (1024x1024) version of these. (The displacement I made in photoshop.)
I’d like to point out, that originally I’ve used noise maps for both the grass colors AND the displacement map as well. They gave similar results.
I have rebuilt the mesh 3 times so far, but what the heck is there to rebuild? It’s a plane object with 9 divisions and some division segments removed (to make place for the separate ground plane).
I’ve tried both the textures and the noise maps with and without tiling. Nothing helps. They seem to be generating this repeating pattern (even when they are not tiled) differently, depending on the view.
I have not been doing anything else in the past 2 days but messing with this stupid grass, and I’m ready to smash my computer at this point. I am very angry and pissed to waste so much time with this seemingly little issue.
Just in case… this is my setting for the VRayDisplacementMod.
I’ve tried DaForce’s recommendation and swapped the maps with a checker map tiled 50 times and it was just fine. The problem crops up when I start to use noise, or noise-like displacements (either texture or map) and a small level - meaning I either tile the displacement a few times, or, in case of a noise map, I make the noise size small, such as 1.
In the last comment, inslaight said that it’s all in the mapping. Well, it’s only a planar UV map on a plane object. There’s really nothing magical about it - so I’d think.
I’m using Max 8 SP3
VRay 1.5 final.
Any tips from the grass pros out there?
Thanks!
Will give it a shot with your maps shortly..
stay tuned 
Well it seemed to work as expected here (no problems)
I created the plane.
added uvwmap.
collapsed it to editable poly
Selected the faces for the path area
detached those.
added a vraydisplacement mod and setup as your settings indicated.
And it rendered fine.
Can you perhaps upload the file your having problems with.
<edit> mmmm
just rendered above the grass and can now see the patterning in one corner very clearly.
Weird.
<edit2>
Ok its the filtering as soon as you turn the filtering and blur of it gets all repetitive. Best to leave it on or place it into a vraybmpfilter and then set the tiling via the uvwmap.
DaForce, thanks for checking!
Well, further experiments show that if I turn the light off and only use skylight, the patterning disappears regardless of the view angle, tiling, or whether I use textures or noise maps.
I used VRay sun for ligthing, then I switched it out to a direct light. No change. Then I turned all lights off, and left only the default vray skylight (multiplied it a little so I can see) and no patterns.
I have no clue how does lighting has to do with displacement patterns appearing or disappearing depending on whether direct light is present or not in the scene…
