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I made 8 test... with different combination of instances and clones...

http://img6.imageshack.us/gal.php?g=68633401.jpg

you can download the images and the notes (word document) here:
http://www.leonardoschubert.com/extra/r ... s_test.zip

My reserach concluded that:

1- instances can't intersect with other objects in the scene or the benchmark will suffer considerable" (even if the instance doesn't have clipmaps)

2- It's okay if instances intersect with other instances

3- clones can intersect other objects in the scene and the benchmark will not suffer. Unfortunatelly as we all know using clones in the scene will increase the file size (.mxs)

So, iether you pay now (clones) or you pay later (instances)

Thanks a lot for the time you spent on testing this.
Very useful information

Agreed. Thanks Leo. Certainly explains alot...

sorry guys... further testing disproved my previous findings!!

I figured if "it's okay for instances to intersect with other instances " then, If I instance the entire model (house) the plants will only be intersecting instances.

Let me tell you, for a second I though I came up with a super bright idea!

I tried up another test (test #9) and I got a benchmark of 14.5 (instanced house)

test #5 had a benchmark of 3.35 (instances intersecting each other / and intersecting the model) so it was a big improvement. Not as good as test #6 = 21.85 (clones intersecting each other / and intersecting model)

So, I tried one final test... I took the scene that was already setup for the final render which I had previously gotten a 3.something benchmark and rendered again. This time, I instanced the house too.... I was expecting a higher bechnmark, but instead I got a 0.44
it took 30min to reach SL= 0.5

I can absolutely confirm your conclusions.
Everytime i had scenes crowded with several instances (trees) i always got a very low benchmark...for the last project i am working on, having read your topic, i've chosen not to use instances at all.
I came up with a huge .mxs (600MB) but the benchmark is something around 140.
I believe you helped me a lot to respect my deadline. Thanks again!

Never use instancing unless you need to for lack of RAM. Also, if you're going to use lots of instanced trees, make sure you use tree models that have leaf shaped polygons instead of leaf "plates" and clipped leaf textures. That's what I have learned by trial and error, anyway.

1-you shall not intersect the emitters
2-you shall keep emitter's polycount and vertices as low as possible
3-dielectrics behind ags is a big no-no-no
4-you shall not try to get real caustics on a pool's bottom
5-don't trust the quadrant
6-interiors will not be lit by physical sky through a window
7-you shall not let a dielectric and an SSS mat intersect each other
8-you shall not use jpegs for clipmaps
9-you shall not let an emitter cast light directly on a reflective surface...

...and now we have the 10th:
10-you shall not let an instance intersect other instances

Mattia, nice summary - this should be sticky (and on page one of the manual!)

I just did a similar round of tests a few days ago. One additional thing I think I found which maybe can be confirmed by my fellow scientists - I noticed that if my original object (from which the instances were taken from) intersected with geometry, I got a similar benchmark hit just as if my original were an instance.

-Brodie

Mattia Sullini wrote: 8-you shall not use jpegs for clipmaps

I did not knoe a bout this one.... Why?

Mattia Sullini wrote:1-you shall not intersect the emitters
2-you shall keep emitter's polycount and vertices as low as possible
3-dielectrics behind ags is a big no-no-no
4-you shall not try to get real caustics on a pool's bottom
5-don't trust the quadrant
6-interiors will not be lit by physical sky through a window
7-you shall not let a dielectric and an SSS mat intersect each other
8-you shall not use jpegs for clipmaps
9-you shall not let an emitter cast light directly on a reflective surface...

...and now we have the 10th:
10-you shall not let an instance intersect other instances

that list seems very short. you must have missed a lot

Well Kami, you know, is the decalogue appeal... ...but we all know that even THE ten rules are not enough

grupo4 wrote:

Mattia Sullini wrote: 8-you shall not use jpegs for clipmaps

I did not knoe a bout this one.... Why?

Because jpegs artifacts may cause some pixels not to be perfectly white and in this case the clipping will not render fine. Maxwell needs 255,255,255 white to work correctly with clipmaps.

Mattia Sullini wrote:...
9-you shall not let an emitter cast light directly on a reflective surface...
...

can you please specify this? or point to a post that covers this. .i missed out on this one..

and by reflecting material you mean one that is very shiny.. like roughness 0

-luke

Maybe because of the caustics it produces? You can do it, you just have to be careful with your scene.