Multiscatter Grass for massive areas

[Roodogg]

Hi everyone. Just wondering how you would do a site approx. 0.5 x 0.5 miles (Mainly of grass - it is farmland in southern England and the client wants to show luscious expanses in an animation). I need to do a few camera movements passing close to the ground.

 

 

This is my current workflow: I am using Multiscatter / MAX 15 / V-Ray 3.1.

 

 

I have broken the ground up into manageable segments of roughly 100m x 100m and applied MS to each segment, I have three grass vray proxy objs made up of billboards. I am using MScatter's camera adaptation with scale falloff and FOV clipping (to save memory I think!)

 

 

I plan to render with IRR map / Light cache with an IRR map calc'd at every 10th frame - my worry is that the changeable scale of MS objects will not play ball with my IRR map calculations.

 

 

Also, is the only way to apply objects to a ground mesh with Multiscatter, the 'Max Count'? I played around with 'Use Density', but it doesn't seem to do anything. Obviously I need the density to be the same on each segment! Ie - always 10 objects per square meter, not simply 100000 per segment (as they're all different sizes).

 

 

Many, many thanks in advance for your help.

[tunakaraman]

Max count is maximum number of instances MS is allowed to use. 'Use density' should work when 'Use random position' is ticked.

[Nic H]

do you really need 3d grass for that ?

 

a matte painting / custom grass map would do a much better job?

then on the shots you pass really close to the grass use 3d in foreground

[Devin Johnston]

do you really need 3d grass for that ?

 

a matte painting / custom grass map would do a much better job?

then on the shots you pass really close to the grass use 3d in foreground

 

Agreed, if you limit your use of 3d grass to the close shots and use a 2d displacement map for the far away grass you'll get the same look.

[Roodogg]

do you really need 3d grass for that ?

 

a matte painting / custom grass map would do a much better job?

then on the shots you pass really close to the grass use 3d in foreground

 

The shots are animated cameras moving over the land so the camera might cover 300m close to the ground in one shot, for example.

[Roodogg]

I don't want to use displacement OR 3d grass for the distance!

[Devin Johnston]

Then a map is your only other choice.

[Roodogg]

Cheers guys.

 

I've figured it out. Using multiscatter with camera falloff allows for me to render expanses up to a point, then I need to start another render having applied MS to the next 'strip' of land. Then obviously composite the sequences in post.

[Francisco Penaloza]

When you use VRay and Multi scatter the render time difference between using planes with cut out or 3D geometry is almost identical, but the quality of 3D geometry is far better. If you'll interpolate Irr maps or LC when using camera clipping of falloff in Multi scatter, it will create flicks when the multiscatter refresh the geometry. Render by passes my be the best option, even trying to render the whole deal at once but only with grass and nothing else, then integrate your grass.

But if you are flying by, at 300m from the ground, with motion blur depending of the speed you actually won't need to render 3D grass. in that case a strong bump or displacement will do just fine.

If you are flying very slow then render per sections will be better.