what affect the most the antialiasing between high contrast

[Jean-Paul Paloux_cg]

Hi,
I would like to know what is the most influent setting to have a better antialiasing between 2 "colored area" very different. Black vs white. When a Black something is touching a white other something, the lines between them is always etchy. I think that clamp output helps a lot without taking too much time. What do you think ?
Jp

[Micha_cg]

what affect the most the antialiasing between high contrast

General I like to use the HDR output, but clamp output make the rendering 8Bit only. So, it is now way for me. Some times I have used the "sub-pixel" options and got good results.

An other HDR way is to render in double resolution and downscale the image per post process. You can use lower noise and GI settings, so the rendertime will not be so much longer.

[dalomar_cg]

what affect the most the antialiasing between high contrast

In that situation its probably best to use Adaptive QMC. The advantage to using Adaptive QMC is that you can control quality through amount of subdivisions, but also through the Noise Sampler in the QMC sampler. Techinically, a min/max rate of 1, 100 will keep the antialiasing quality within the accepted noise threshold. The default max rate of 4 is usually pretty good for previews (you can set it to 2 for really fast previews). Although most of the time a max rate of 100 is not neccesarily needed, a setting of 25-50 is usually a good setting for quality renders. The great thing about using Adaptive QMC is that if you do tests or previews with a higher noise threshold (like .01-.05) and then you lower it for final renders (.001) it should increase the quality of the antialiasing.

As far as clamp output's affect on antialiasing quality, I've never really looked at that, so I can't say what effect that would have.

[Micha_cg]

what affect the most the antialiasing between high contrast

My experience is, that full Adaptive QMC dosn't help at high contrast edges.

[Gijs]

what affect the most the antialiasing between high contrast

The reason why you get AA problems at bright edges is because our display cannot show a difference between a 255 and a 267 or even a 1000 or more (in rgb values). Vray actually makes a good AA at those points, the only thing is that you can't see it. You can see it by lowering the exposure until the brightest pixel in your rendering falls in the 0-255 range (at least if clamp output is off). If clamp output is on, it has the disadvantage that you cannot tweak the lighting correctly anymore after rendering, but it has the advantage of faster rendering and no AA problems, especially in combination with subpixel mapping.

[Micha_cg]

what affect the most the antialiasing between high contrast

Which way do you go Gijs?

[Jean-Paul Paloux_cg]

what affect the most the antialiasing between high contrast

very interesting stuff as been said. Thank you very much. Now, it's time for testing.

Jp

[dalomar_cg]

what affect the most the antialiasing between high contrast

I get what you guys were saying about high contrast stuff now. This is a night shot for a project for school. It was done in VRay for Max, but its all the same. I did two tries with the antialiasing, one with Adaptive subdivision @ 0/3 min/max rate and Adaptive qmc 1,24 subdiv. Both came out with similar results(I think this one is the qmc version).


Its for the splash page of a dvd, so thats why its off to one side

[Jean-Paul Paloux_cg]

what affect the most the antialiasing between high contrast

one easy way is still to render bigger and reduce in a graphic program.
Jp

[dalomar_cg]

what affect the most the antialiasing between high contrast

I found an interesting article. Its mostly on motion blur and depth of field, but at the end there is a good section on antialiasing at high contrast areas.
http://www.joconnell.com/view.php?category=3d&view=28
Hope this is helpful.

[Micha_cg]

what affect the most the antialiasing between high contrast

... this photoshop plugin can help too - Powerretouche. Test the demo.