GI calc setup for the fastest rendering with scattering apps

[PIXELBOX_SRO]

Hello,
Thought i would bring this up...

i am currently using IR and BF with
IR at 120/20
BF at 20/3
DMC 1/5
noise threshold at 0.001
achieving times around 2 hrs on i7 at 3.2 Ghz

i am getting some artifacts in the GI calc though...have a look at the sample image...how do i get rid of this?




what is your best setup or recomendation for the good quality/rendertime ratio?

Thanks for your inputs

Best Regards

[Crayox13]

What are your IR settings in terms of subdivision?

How did you arrange the grass generation? I guess that background plane (which seams to have much more dense grass) is separate from the front. What's the number of max objects, and what is one object composed of? One or several leaves?

[PIXELBOX_SRO]

its iGrass so the clutter is done using ther default leaves for this type of grass
scettered on one object (foreground/background)
IR is -5 / -3 (3500px wide image) 120/20

[jacksc02]

Martin,
I would do the grass/building in seperate passes.
Gives you far more control over GI quality

[PIXELBOX_SRO]

Hi Chris,
yes thats hwat i thought i would do ... is this common though?
I thought there must be some setting that might work reasonably

[PIXELBOX_SRO]

plus...the animation would be a bit difficult comping all the passes together no?

[jacksc02]

If you are doing animation then I would 100% recommend compositing the grass as a seperate layer.
What are your BF settings for secondary bounces?

[PIXELBOX_SRO]

subdivs at 20
secondary bounces 3

what sort of workflow do you suggest....should i render the pass with alpha matte? i mean everything apart from grass in matte with alpha and shadows from grass burned in the alpha?
that shoudl avoid some ugly alpha fringing...?

[Crayox13]

Not sure how iGrass works, but you have to use MS as well, right? What's your max object count, I mean how many do the MS generate?

[PIXELBOX_SRO]

sure i use MS with it...
their default plane object is quite large
so i count its area and make a ratio which i apply on my object
example
their plane is 100 square meters with object count 3000000
mine is 30.....so.......3000000/3.33333
that way i am sure am using the same amount of objects on my custom object as they do

[Crayox13]

iGrass really looks amazing on their showreel, but I still don't quite understand what it is. It's not an engine, right? It's just objects that you put in MS and scatter? Because then it'll be the same for me if I used iGrass or my own. I saw huge surfaces on their reels, so I guess it should be possible to do them with MS.

Oh, how come you don't use density under random position? That way the software does this calcs....or do you find it to be faster when rendering if you don't use too high max count?

Do you, or iGrass settings of MS, use collisions?

[PIXELBOX_SRO]

i dont really know man, am not the best person to ask as i ve been only using MS shortly.
i guess for the bisg surfaces, they defo use camera clipping and other means of scene optimization.
iGrass is a set of nicely done 3D grass meshes and preset scenes that you just apply to your project if you want...but you can just take individual stems and make your own grass.
when i comes to collisions, i dont think the iGrass uses them much

[Crayox13]

It seams that using "use density" slowed my renderings. Still not sure, but after few tests, and disabling it, I can render the scene now.
Although I tried BF, as you suggested. I put the render last night, and still this morning, the last, third, pass of GI is not done. So I really think LC is much faster. The scene also has vegetation, and I think that's too much.

You can check your MS settings for the grass if collisions are checked or not. Also, if the "use density" is.
thx