Opacity mapped leaves etc

[tricky]

It has always been that using opacity maps with Vray has been a no-no as vray is far slower rendering overlapping opacity mapped geometry than it is pure geometry itself.

Is this still the case with SP2 and will it be the case with SP3?

We use Onyx to generate trees and convert them into vrayproxies. They are used both at long distance and close to the camera. Far away from the camera, they look fine, but the closer they come to thew camera the more they fall apart as the leaves are little squares of colour (with a bitmap of a leaf 'bodged' into them) rather than nicely defined leaves as you would hope for.

Trees, obviously, have shit loads of geometry in them, and there are multiple layers of leaves overlapping each other from the point of view of the perspective.

Must I continue to use 'square' low detail leaves in this way in order to achieve realistic render times?

[peterguthrie]

Somewhere in this marvellous forum there is a AEC leaf replacer script which I use to replace square leaves with geometry leaves. Obviously this increases the file size of the proxy but whats the point of a 12gb 64 bit system if you arent going to make it work?

If you dont fancy all the extra leg work, then give (no filtering) opacity maps a go, they aint that bad

[Sascha Selent]

Maybe this?

http://www.chaosgroup.com/forums/vbu...ad.php?t=32898

[Klonsemann]

What about a solution haven both advantages ?

You could build a mid polycount leaf geometry for far away leafs and having a correct opacity map on that mesh, with sharp filtering and blur settings for near leafs.
You can blend this via distance falloff.

[timmatron]

I have used opacity maps with Onyx trees & Vray quite a bit and have not really had anything to complain about. Maybe it's a little slower than geometry, but I wouldn't say its slow by any means.

And yes, when you do switch to geometry leaves, it does create so many more polys which in turn makes your proxies a lot bigger, takes longer to load up etc.

Are you having problems with render times or just going off of what you've heard in the past?

[duke2]

I've got it in my head that the benefit ratio is 1:4. For example if your tree has 4 times as many polygons as your opacity mapped tree, it will render in the same time, but beyond that and it will start to render slower.

I don't know where I pulled this figure from.

[dellis]

...from "madeupstatistics.com"...just kidding!