grass displacement issue

[insleight]

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?

[studioDIM]

2d mapping doesn't solve it?

Lele

[insleight]

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

[RErender]

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.

[insleight]

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.

[DaForce]

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

[insleight]

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.

[DaForce]

Have a quick glance at this thread.
http://www.chaosgroup.com/forum/phpB...ic.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?

[insleight]

https://sneakybiscuit.sslpowered.com..._insleight.max

I really appreciate it. I have also tried using a regular displacement map instead of the vray modifier to no avail.

[DaForce]

Having a look now.

[DaForce]

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.

[insleight]

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.

[DaForce]

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

[DaForce]

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.

[insleight]

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.