G.I. artifacts on horizontals?

[D.B.]

OK………..I have to ask…... How do you folks get rid of artifacts on those long horizontal overhangs and keep the render speed reasonable?.... I’m talking about using G.I. on exterior architecture scenes with eves, overhangs, and things like horizontal siding. The rest of the scene may render fine with good speed, but not those areas!

I’ve used these options…

Pure Stochastic, beautiful results…but the render time is thru the roof!

PhotoShop…much quicker than Stochastic…but I’m not a wizard with this program

G.I. accuracy for the problem material set at 100%...(98%still still makes artifacts with long render times..so why not 100% with long render times?)…

What have I missed?

[edub]

what are your stochastic settings and min/max resolution?

 

you should be able to get away with less than 100% accuracy, as long as your other settings are adequate - please post more info.

[D.B.]

My latest attempt was on a quite simple building,and the settings were rather high (for me) 2000 ss, 500 min, and experimented with up to1500 max samples...... and still had artifacts under the shingle edge and beneath the siding. I could have increased the settings, but that would have taken far too long for this small project..

 

What seemed to work for the rest of the scene was about 500-800ss, 40-60min, and maybe 150-200max samples.

 

Neither of these settings clarified the artifacts, but setting the G.I accuracy in the siding and eve materials at 100% worked...(but 98% accuracy left enough to be noticeable)

 

Thanks...

[erona]

GI accuracy need not to be that high. YOU CAN force GI accuracy by object especially to those which results to much artifacts such as trims, moldings, etc.

 

you may want to do experiments first.

set GI accuracy back to its default value of 70.

depth = 1 GI accuracy

stoch = 300

min = 50

max = 100

 

now play with the min value to determine which value reders fastest. I usually end up between 70 - 100. max can be determined when there are least artifacts found on where surfaces meet such as inside corners. usually around 300 - 400.

 

stochs fairly around 600.

 

to rid artifacts on horizontal details, add a compositing tag on those objects, enable GI accuracy and set it a step or two hegher than the global GI value.

 

hope this helped you

[D.B.]

Thank you very much the suggestion. I'll set aside some time to experiment with those settings.

[STRAT]

yup, Robin speaks good sence there

 

Render tags are your friend. also, dont be afraid to substitute GI with AO. localised of course