Hey! im making a large architectural scene. With particle grass, the problem is that the grass makes it impossilble to work with the scene and its not even possible to render . Any tips on how to fix that ?
have a great day !
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One very good and practical strategy is: compositing. You first render the architecture, then in an entirely separate render you turn your attention to the grass. Finally, you composite the two things together.
Use “MultiLayer OpenEXR” files in all of your intermediate work, so that the data is exactly preserved throughout. Render your “final video files” from this completed (now, not “MultiLayer” …) master.
If you watch the “making of” videos of almost any Hollywood production, you will observe them making very frequent reference to multiple layers of this idea of compositing: “beauty passes” and so on.
In reference to film photography, the legendary Ansel Adams perhaps said it best: “the photograph is captured in the camera, but it is made in the darkroom.” (Or, as Adobe® likes to say these days, “the lightroom.”)
“Rendering” is therefore an intermediate step.
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Okey thanks. I did try just now to do so but i think my it worked fine. But when im rendering the grass particles only it sill is to much.
There is no magic bullet, you need to lower the memory cost.
In these case, I try first to get some numbers, like memory cost, number of vertices, triangles.
Then, I try to get what objects, or group of objects takes the biggest amount, I write down all the numbers and start tweaking the bigger objects.
In your case it sounds obvious that it may comes from the grass, but it can be surprising what really cost the most. When I do some checks I always find some costly objects that looked innocent that I didn’t think of in the first place.
Textures also takes a lot of memory space, you may want to reduce some of them. One 4k texture will take 64Mb in memory, if it’s 8k it’s four times the cost (256Mb).
If you do PBR with a color, roughness and normal map, at 4k it’s 64x3 (192Mb) for a single material.
By turning them into 2k images you get 16x3 = 48Mb.
One good way to see the texture cost is to make a material override in the renderlayer, or get rid of all material, render a frame and compare the numbers.
Do you use instancing ? If you have several time the same objects you can reduce the memory cost and speed up rendertime with instances.
You can also tweak the grass settings. I had a similar issue one time, where scenes where hard to render, by hunting down the issue it was the hairs of characters. We had like 12 characters, and by just lowering the particles children amount on each character it was possible to reduce memory cost to something manageable again, without real visual changes.
Something else that you can do, but it will take some times, is to use geometry nodes for the grass and use camera culling :
Everytime you do an optimization, write down the numbers and compare to what you had.
It’s really easy to get lost to a point you don’t know what did what. You may think the issue is in particles, in fact it’s in textures. In that case you can even get rid of particles, the scene won’t render anyway. With some number written down it’s easy to catch these kind of situations.
These are some general advice, it’s simpler to provide a more specific answer when having access to the scene.
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Thanks! i did use instancing for some of the bigger stuff. The scene is to big to upload here i cant make a similar scene to upload
Here is a picture of the scene
Ok !
Sounds like a good candidate for camera culling,
First try to see if it can render without particles just to be sure.
Then try to re-do the grass using geometry nodes and camera culling.
If you can get rid of all the particles outside the camera frame you should be good to go.
how the grass is made ? is it some mesh or just hair particles ?
yepp i possible to render without particles. Its Hair that i have textured
Ok !
So another solution is to look how hair are subdivided :
The steps value, try to lower it.
And how they are rendered :
You can reduce the curve subdivision, or switch the shape to 3D curves,
I’m not sure the best settings here, you need to test !
One solution is to use real geometry instead of hairs, you can check some tutorials on creating grass with blender.
But , if you have some time, look for doing that with geometry nodes, you’ll have more control, and the ability to do camera culling.
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Thanks i tried another thing i made a vertex group where i wanted the grass and then set the hair to the vertexgroup. Not sure it will work with the whole scene. But with some tweking mayby it will
Cool !
The important thing is to reduce memory usage, it’s great if you’ve found your own way, and you can always come back to what has been said here if that’s not enough !
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Yes 
thank you so much
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