hair antialiasing...

[Stri]

I'm using Shag:Hair-turned-geometry-hairs for this character and my only problem so far is the antialiasing. I'm using Adaptive samples with min=1 and max=4 and after 29 minutes the result is the image above. With lower settings, I got by with only 8 minutes. After some testing, I settled with the mitchell filter because of the blurring which I think might help with the hair.

Though I'm happy that Vray's antialiasing is superbly faster than brazil, I was hoping that there might be a way to get better antialiasing on the hair and not sacrifice so much rendertime. This is my first time with rendering hair in Vray so... if any of you guys out there know how I can improve antialiasing on the hair, you're tips are greatly appreciated.

[maxim8er]

Have you tried using the simple 2 level antialiasing method? I have found that it gives superior results to adaptive when rendering fine detail.

Give it a try.

V Miller

[Stri]

maxim8er, I followed your advice and used the simple two level AA method with the same min and max values. From 29 minutes, it dropped to 18 minutes. But, the AA was noticeably worse than the adaptive samples. I had to raise the max value to 6 to get the same result as with the adaptive sampling and the rendering time jumped to 40 minutes.

[maxim8er]

here are two more suggestions.

check the random box for the antialiasing method you are using.

change the aa filter to something other than area. try cook variable
these filters are often overlooked but make a big difference in the quality of the antialiasing.

V Miller

[losbellos]

this is an interesting issue, I think if you have a lot of little stuff (hairs), you might be better use fixed rate. Its faster in glossy, grass etc. Maybe here as well.

[richard_rosenman]

To avoid aa buzzing with fine geometry such as hair, you can render high rez and then bicubically scale down the image. So you trade off faster rendered images due to the lower aa, with longer rendertimes due to the higher rez. This will effectively eliminate 95% of aa buzzing.

-Richard

[dusan]

Don't forget to lower the irradiance samples if rendering this way, i.e. if rendering 4x larger image, reduce from lets say -3,-2 to -4-3 and the calculation will be the same.
Someone correct me if im wrong.

[RErender]

To avoid aa buzzing with fine geometry such as hair, you can render high rez and then bicubically scale down the image. So you trade off faster rendered images due to the lower aa, with longer rendertimes due to the higher rez. This will effectively eliminate 95% of aa buzzing.

-Richard

How much bigger ?

[richard_rosenman]

We've rendered images containing grass with camera pull-ins at NTSC resolution (720x486) which buzzed like crazy. We rendered those same frames at 2160x1458 and then scaled back down and 95% of the buzzing was eliminated. Of course, you don't have to render that large, but then you may get more buzzing when you scale back down.

-Richard

[vlado]

Instead of scaling the resolution, you can set the Min rate of the adaptive sampler to be greater than 0. Min rate of 1 should be enough.

Best regards,
Vlado

[vlado]

Also, do not use sharpening filters. Cook, Mitchell-Netravali, Catmull-Rom are all sharpening filters which will increase moire effects. Use blurring filters like Soften, Area, Video etc.

Best regards,
Vlado