Why is my alpha pass binary (just 0's and 1's) in Cycles?
Why is my alpha pass binary (just 0's and 1's) in Cycles?
In Blender Render, my rendered alpha pass has intermediate values (e.g., 0.83) at the boundary -- great for anti-aliasing compositing!
However, when I switch to Cycles, my alpha channel is always binary, i.e., consisting of only 0's and 1's.
For some other reasons, I have to stick with Cycles. How would I produce an alpha pass with intermediate values in Cycles?
@wizzwizz4 Since there is an image showing what it is and there is even explanation in brackets in the title, I fail to see the problem you are trying to solve. At least people will learn what Binary image is. Black&White is used as synonym for Grayscale, it's misleading same as Monochrome was. People not understanding something is normal and does not justify avoiding correct terms, it even might spread confusion. Binary is the best how to call this and there is no problem with it because this is not a casual site, here you will come across many more technical terms.
– Jaroslav Jerryno Novotny
Aug 25 at 16:10
1 Answer
1
You have only 1 sample set for Cycles:
Any particular sample in Cycles will return either 1 or 0 for the alpha channel. Antialiased alpha edges are built up by averaging multiple samples, some of which strike the occluding object and some which do not. Using a larger number of samples, such as 16, will fix the issue.
This is cool. But how many samples are enough? Hmmm.
– Sibbs Gambling
Aug 25 at 14:35
That's one of those nebulous "it's enough samples when it's good enough for you" things. Technically, any sample count greater than 1 gives some antialiasing. The more samples, the more antialiasing. There's no way to say definitively when it's enough. 10-20 is a nice ballpark in a lot of cases, but who knows? Rendering is complicated.
– JtheNinja
Aug 25 at 20:44
Roughly speaking, ~32 samples will clean up images with only diffuse and no bounce. But usually you'll have much more than that. If you have bounce light, you're looking at ~250 for diffuse to clear up, ~500 for glossy, and anywhere from 1,000-3,000 if you have complex reflections, glass, volumetrics, etc. This can be brought down with certain settings, and the use of the denoiser.
– Drudge
Aug 28 at 19:21
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@wizzwizz4 Monochrome is single chroma, single hue in colorspace. The term Binary image is correct here. Binary is subset of Grayscale and that is subset of Monochrome.
– Jaroslav Jerryno Novotny
Aug 25 at 15:24