Instancing Optimisation

[MeyerAdrian]

Hi,

I have a question regarding optimisation for large scale instancing scenes (forest environment in this case).

Say I have 20 different trees, pre exported as .ass archives.

I instance them 1000 times.

Is it actually performance beneficial to use different LOD versions for the trees?

So then for example having 20 hires and 20 lowres Trees, using the hires for ones that are close and lowres for background objects.

Seemingly this should be less heavy to render because of much less Polys, but due to instancing, this might actually mean more Polys in memory to render? Is it better to not use LODs and thus having less unique Objects but with more Polys?

Another question is, with Tree leafs for example... Say a Leaf has 3 Polys or so, each tree has between 50.000 and 150.000 Leafs. So around 150.000 and 450.000 Polys total.
Would it be more efficient to render the Leafs as unique Geo, or instance a set of say 5 Leafs with 3 Polys each. I guess this is actually inefficient because the instancing effort, point attribs etc. are actually more work to do for arnold?

Is there a kind of Rule of Thumb to judge from what Instance Object Polycount instancing is actually faster?

Thanks!

PS. actually using HtoA

[MeyerAdrian]

Any experts willing to share some insights about this?

Would be awesome