OTOY Forums

Hi

I've made a decent tree, by scattering some leaves onto a few twigs, and then scattering these in turn onto boughs, and then have a trunk, all grouped together into a geometry group

when I then try and scatter all this bunch say 10 times, all GPU's fail - admittedly it is trying to render approx 7 million meshes, but of course the number of original triangles is relatively low...

is there an upper limit to the amount of instances you can get onto a GTX590 ?

I vaguely recall their might be a polygon limit, which is easy to exceed when dealing with 7million polygon meshes.

Hi sdwhitton,

What does octane say for your used/available/total vram.
Do 8 trees work? 5 trees? 2 trees?

Thanks
Chris.

Hi all

Yes, didn't realise that the 'number of instances' is a VRAM hit too, so yes 5 or so trees work

so, I've thined the number of branches, leaves etc

oops!

Usually there isn't much of a VRAM hit.
Say you have a 1mil triangle tree and then you instance that, only a minimal amount of information is needed to reproduce the tree in a new position/scale. (not another 1mil triangles). How much more VRAM gets used per tree?
EG: you have a 600,000 triangle mesh that takes 83.8MB for geometry, you scatter this 100,000 times and the geometry size only increases to 96.0MB

I would say that your best option is to create the whole tree and then instance from there (unless you have some crazy insane high poly tree that you cannot do without instancing). Render speeds drop considerably when you do things like have 600,000 instances of a simple plane (which may be the case of your leaves).
Or at least turn the twigs with leaves on them into geometry (rather than each leaf instanced).

Thanks
Chris.