About final gather accuracy


I’m tryng to get a good FG preview of my model without awful render time, here is my problem:
I’ve a scene of 23 inches, so i start with “standard” settings like:

FGRays: 800
MinRadius: 0.23
MaxRadius: 2.3

and these are the results:

as u can see most of the details have a realy bad visibility. I’ve tried many FG settings, but I’ve got a quite acceptable image only with:

FGRays: 800
MinRadius: 0.002
MaxRadius: 0.023

Obviously render time is realy long, also the image still looks a bit granular(and it seems to be not depending by FGRays)

So, what can I do? should i try other FG settings? Maybe some other lighting solution like ambient occlusion(never used it)?


To get the details underlined, I’d really try to use an ambient occlusion shader like dirtmap. It’s fast and makes even the tiniest cracks visible.
Try it and repost your test!



have you tried with 0,0???

many times i use this and they always seem to be fine.


use FG view dependant


Yeah, I think an AO shader would be much easier. If I were using FG though I think yashu is right, use the Final Gather View option. It changes the FG radius values to mean radius in pixels, rather than world units.

If you have Maya 6.5 this is as easy as turning on the Final Gather View option in the Render Globals. However in Maya 6, you need to add the boolean attribute ‘finalGatherView’ to the node ‘miDefaultOptions’ and then tick the new checkbox of that name, on that node, under the Extra tab.

With that enabled, you could try settings of like min 1, max 3. So no details of 3 pixels or larger should be missed. You can start with low numbers of rays and then work your way up.



That’s seems to be exactly what i was looking for floze.

neowar3020: Yep, I’ve tried, with results like the first image above.

New rendering test:

Ambient Occlusion - 30 samples - Render Time: 00.01.04

Image imperfections depends by anti-aliasing quality.

Final Gather View - Min: 0.1 Max: 1.0 - Render Time: 0.06.32

Dirtmap definitely wins, i’m experimenting various implementations, thanks guys

PS: great tutorials jozvex, keep writing them!! :buttrock:


Image imperfections depends by anti-aliasing quality.

also the samples in the dirtmap attributes.


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