Tried to Make Grass, and it is a nightmare

D

dynsight

0
Okay, I tried to make realistic grass following this guideline:

https://cheetah3d.com/forum/index.php?threads/10360/


but the result is very flat.

https://momento360.com/e/u/5b6e71e4...other&heading=-44.5&pitch=-2&field-of-view=75

(this represents some nightmares I have been having). My question is, what am I doing wrong? I hope this is enough info

displacement map.png
 
* Increase the offset of the displacement. I used .1 as a value.
* Cranking up the sections / adding a submodifier may help.
* You do get a lot of geometry ( 2m polys in my example).

Screenshot 2020-09-01 at 09.09.24.png
 
There are a few posts in the forums about making grass. There's also a script that was originally meant for hair, but it can be used for grass also.
 
I spent a long time with grass in this thread/project

https://www.cheetah3d.com/forum/index.php?threads/13729/

51 Chevy Outdoors - Jun5_FINAL_sm.jpg

The most important things to remember are that you can put multiple grass-like objects within a single Particle Mesh object, and then that you can use the "Polygon selection" property to apply different Meshes to different areas of the same target plane. I used this strategy by making several Particle Mesh grass mixes (taller, short, greenish, yellowish, etc), then applying them to different polygons on the ground plane. Viewed from a low angle, the overlapped softly. I also used some transparent color on the ground plane, which was overlapping the HDRI, which already had a grass image below the scene. Grass also works very well if you use some depth of field.

The trick is using a good grass-resembling texture below the meshes so that you don't need so to create so many thousands of grass blade objects in the Particle Mesh.
 
You might want to do it in Blender (free) and import it in Cheetah. It's the fastest , most 'natural' way.
 
Clever use of one or more particle systems with simple quads will get you a long way. It's likely to be problematic if you want rotate the camera a lot during an animation…
 
So I put this together. With 2000 grass particles Cheetah 3D's live view looks pretty great and is perfectly responsive, but the Cheetah renderer is having issues with even 200 particles and 24 bounces with reflections switched off (and it doesn't look like it should need more than 5-10 bounces in that case). I'm pretty sure I tried this same thing with much older versions of C3D and it worked fine. (The same approach could be used with actual geometry and wouldn't run into rendering issues, but would probably be pretty gnarly to deal with.)
Screen Shot 2020-09-02 at 2.59.31 PM.png
render issue.jpg
Screen Shot 2020-09-02 at 2.59.16 PM.jpg
 
@Radian Actually you could apply that logic to (almost) any problem in Cheetah or any other 3d app non-blender. But there are people who just don't want to use that app if the problem itself can be solved.

@ the rest ...
The real problem with stuff like this Helmut already mentioned: The almost insane polycount you can get in the end, be it with displacement or particles.

So I also would recommend a mix of different techniques if anyway possible (foreground particles, middleground maybe displacement, background a good texture as Monkey suggests.

One way to do it could be particles in the foreground, "sprites" in the background (single polys with an image and an alphamap, like cardboard grass patches. This is a little bit softer on the polycount)
 
Thanks for all the feedback. My issue is that this will eventually be a 360 walkthrough, so the grass views will be dynamic. Still you have given me lots to think about and try out.
 
Nice progress!

A few optional suggestions: Keep wide lettuce-like leaves short and closer to the color palette of the ground texture to help it blend in, keeping the feel of thicker, irregular ground. Use color to help you: You want the blades' geometry to be simple to lower the rendering cost, but using a flat color on them accentuates just how flat the shapes are. Choose a simple material with just a subtle color variation, implying a changing surface shape that's not really there. If it's just the color that changes (not complex stuff like reflection, emission or bump), it doesn't add a great deal of strain to the processing. Let taller blades be thinner, and in a slightly lighter color that stand out just a little from the low, thick coverage. And remember that even though you are working hard on the grass, it probably shouldn't fight to be the focal point of the user ( unless it's a deliberate obstacle, like wandering through a cornfield ) - keeping things subtle is often hard work.
 
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