Grass

[flashawd]

Hi - can anyone show me a sample of a lawn of grass they have done using hair material?

 

Thanks,

Eric

[photoman]

Heres one of my works in progress:

Heres a quick one I made. VERY simple:

Hope it helps.

 

-Photoman

[flashawd]

Hi - yes that's helpful, thank you.

[R Reynolds]

The grass on the background hill was my first presentable attempt. More a field than a lawn.

[Caroline]

You could try multiple emitters with differing colours and lengths. Multiple hair materials. Decal of an actual grass photo controlling the colours.

 

Let us know the settings when you find them out.

[robcat2075]

The grass on the background hill was my first presentable attempt. More a field than a lawn.

 

Great shot Rodger! You must tell us more about the grass.

[R Reynolds]

You must tell us more about the grass

 

If I must, OK here goes. Keep in mind that it's been almost three years since I did this research so I don't remember every parameter setting but I can give you the broad strokes.

 

The first thing I discovered was that rendering a landscape of grass/hair takes a long, long time, at least on a 1.5 Mhz Athlon. So I spent a fair bit of time trying to determine the minimum number of blades required to closely suggest grass as opposed to trying to accurately simulate every blade. On a model railroad, the stars are the locomotives and rolling stock not the scenery.

 

My first "trick" was the material I applied to the ground, grass.mat, shown in the first image. This suitably noisy "quasi-grass" has blobs of contrasting color to suggest small discrete plants and really helps fill in the gaps between individual grass blades. The second trick was to use AM materials to produce images that can be used as maps to control blade color, length and density. The final trick was to realize that the grass texture you need in the foreground can be far different than what you can use in the background.

 

The next three images are reduced versions of the maps used in the image of the hand-car and shed. The length and color maps are made with three different materials with gradient fades between them. The leftmost parts of the maps are close to the camera's possible locations while their rightmost parts will be in the distance, well in the background of the image. As you can see, I want more granularity, in both height and color, close to the camera to suggest more detail. My most surprising discovery was how little density I needed in the background and stiil have believable grass. So the density map basically concentrates grass closer to the camera. On the tall grass I seem to recall using the grooming tool to bend various sections of blades in realistic directions.

 

The last image is an earlier test render I stumbled across while trying to refresh my memory on this process. It's closer to the original request for a lawn like landscape and uses similar maps to those attached. The repeated picnic table is just to give a sense of scale and distance.

[flashawd]

Nice - thank you for all the samples. ;-)

[Caroline]

That's excellent - I'd never thought of the gradual fading out.

 

Thanks

[mtpeak2]

Here's a scene from TWO with hair grass.