Possible to get perfect anti-aliasing without AA filters?

[Rob Burns]

I feel like I am often fighting minor aliasing issues, usually where a very bright reflection is right next to a dark material. A good example would be a chrome drawer handle with bright glossy reflection highlights, sitting on a dark wood drawer face. See the attached image as an example (in this image I used an AA filter to smooth it out, but without the filter the drawer pulls are slightly aliased). I've tried many approaches to removing the aliasing that shows up at the edge of the reflections, like setting the materials glossy reflection subdivs very high (100 to 250), setting the Adaptive DMC sampler max settings very high (min 2 / max 50), setting the DMC noise threshold very low (0.001 to 0.0005), setting the clr threshold in the adaptive DMC sampler very low (0.001 to 0.0005) turning on sub-pixel mapping and still there is slight aliasing on the chrome handles. The only ways I've found to get a perfectly smooth image with no aliasing is to clamp the output to 1.0 and/or to use certain AA filters like the quadratic filter. The problem with clamping the output is you loose the high float values needed for many things in After Effects, and with the quadratic AA filter you loose some sharpness. Is anyone able to get perfectly anti-aliased images without clamping output or using AA filters? Is there something I'm missing?

[vlado]

Is anyone able to get perfectly anti-aliased images without clamping output or using AA filters?

In short, what you want is impossible. The reason for the aliasing effects is the fact that the image is composed or rectangular pixels and there is no way around that (well, maybe hexagonal bitmaps ). Antialiasing filters were introduced specifically in order to counter this effect to some extent; it is also the way that digital cameras deal with the issue - there is always some amount of light spill between neighboring pixels.

Best regards,
Vlado

[Rob Burns]

Ok well at least I know I wasn't doing something wrong then. I guess I'll stick with the quadratic AA filter - overall it's been doing a decent job for me. Thanks!

[chriserskine]

could try rendering much higher resolution. medium format camera's don't have AA filters (40 - 200mp), and I've just started using a D800e (36mp) without one (kind of). and haven't seen too many issues with it.

so less of a need for one when shooting at high res. maybe it worth testing it out. though not that useful for production.

[vlado]

could try rendering much higher resolution. medium format camera's don't have AA filters (40 - 200mp), and I've just started using a D800e (36mp) without one (kind of). and haven't seen too many issues with it.

While this works, of course, it effectively kills some of the effects that Rob wants to preserve. It's quite similar to using subpixel mapping and a slight blurry filter.

Best regards,
Vlado

[Morbid Angel]

Im not sure if coverage pass is available for max yet, but you could use it to explicitly specify aa for certain areas only and for certain passes only. This could get a bit tricky though...

[joconnell]

We used to do a similar trick of using an edge detect filter in after effects or find edges in photoshop to give you the edges of objects, then use that as a matte for a blur effect. The sample rate pass would be perfect for that too.