[WIP] Pixar Style Grass Experiment (Feedback Needed)

j0pine4

Looking to recreate the style of grass from Pixar's Monsters University (I know it's weird and grass seems boring but it's a good exercise in scene optimization, shading, and lighting ). The problem I'm running into is building an interesting composition. Right now it's just kind of "Oh look, it's some grass on a plane." 

Film Reference:


Some Early Test Renders:


Higher Resolution Version:


I thought it would be enough to add the sidewalk, a tree, and the fence for a basic composition but I'm curious as to what you think! Another Idea I tossed around was recreating the porch in the top middle reference image, but that becomes "Look at this porch" and not "Isn't this some cool grass?"

All rambling aside, all feedback/ideas are welcome! Thanks!

birb

What's the target engine (game or just a render) and what are you using to generate that grass?

j0pine4

 @birb This is a Cycles render within Blender. Simple particle system with some random scale and rotation. 

birb

j0pine4 said:

 @birb This is a Cycles render within Blender. Simple particle system with some random scale and rotation. 

Nice! I guessed from the look of the noise but wanted to be sure.

So, the first step to recreate an effect is to break it down into its basic components and understand it. You're on the right track, but your grass is missing the basic growth unit seen in the Pixar grass, making it too uniform. The charm in the Pixar grass is the liveliness created by the random repetition of those units. Achieving the same result will help you to create nice compositions by generating "empty" areas where the eye can rest which won't be fully empty to the point of being negative space.



You can get a semi-circle like this by using a Kink for the children particles then rotating the guides. This won't be the most performant method because there's a lot of unneeded grass under the emitter as you can see in the example below but it's quick to setup. An alternative would be to create a bunch of clump variations, turn them into objects and stuff them into a collection, remove the excess underneath, then use them in a new particle system.



I use children of the Simple type most of time because they're easier to control and let you use cool things like adding a bit of Twist to get organic results. I love using Clump Curves for the same reason. The grass in the ref has some stray taller stalks in the middle of some clumps. You could use a taller than needed hair then the Length and Threshold settings to get the same result, but they'll likely look too thick and Blender offers no granular thickness control over children in a same system.

My tip is to use the trick of duplicating the particle system, making it unique and modifying it to emit fewer, longer and thinner hair strands, then change the children system to emit a single one just so you can get the long and thin strands right. I didn't touch the number of keys or anything so that grass is curvy, but the grass in the ref is really spiky. You can reduce the number of keys to get the same look with the bonus side effect of having a slightly lighter system.

Don't forget to add a slight color variation to the grass material. A very subtle hue and value change takes you a long way by creating more separation between stalks.

Lastly, try to use a more angled main light source / HDRI so the clumps cast better shadows. The example above is uses the sunrise studiolight.

j0pine4

birb said:

j0pine4 said:

 @birb This is a Cycles render within Blender. Simple particle system with some random scale and rotation. 

Nice! I guessed from the look of the noise but wanted to be sure.

So, the first step to recreate an effect is to break it down into its basic components and understand it. You're on the right track, but your grass is missing the basic growth unit seen in the Pixar grass, making it too uniform. The charm in the Pixar grass is the liveliness created by the random repetition of those units. Achieving the same result will help you to create nice compositions by generating "empty" areas where the eye can rest which won't be fully empty to the point of being negative space.



You can get a semi-circle like this by using a Kink for the children particles then rotating the guides. This won't be the most performant method because there's a lot of unneeded grass under the emitter as you can see in the example below but it's quick to setup. An alternative would be to create a bunch of clump variations, turn them into objects and stuff them into a collection, remove the excess underneath, then use them in a new particle system.



I use children of the Simple type most of time because they're easier to control and let you use cool things like adding a bit of Twist to get organic results. I love using Clump Curves for the same reason. The grass in the ref has some stray taller stalks in the middle of some clumps. You could use a taller than needed hair then the Length and Threshold settings to get the same result, but they'll likely look too thick and Blender offers no granular thickness control over children in a same system.

My tip is to use the trick of duplicating the particle system, making it unique and modifying it to emit fewer, longer and thinner hair strands, then change the children system to emit a single one just so you can get the long and thin strands right. I didn't touch the number of keys or anything so that grass is curvy, but the grass in the ref is really spiky. You can reduce the number of keys to get the same look with the bonus side effect of having a slightly lighter system.

Don't forget to add a slight color variation to the grass material. A very subtle hue and value change takes you a long way by creating more separation between stalks.

Lastly, try to use a more angled main light source / HDRI so the clumps cast better shadows. The example above is uses the sunrise studiolight.

Oh wow! Thank you so much for the thorough breakdown! I'll make sure to implement all your tips!