Major Improvement to Cycles in Blender 2.71
For a while, high levels of noise have been a major pain point for Cycles, a raytraced rendering engine used in Blender. A variety of techniques have been used to mitigate noise, many of which sacrifice realism for speed.
Things got better with the ntroduction of the branched path trace integrator. This alternative integrator, instead of performing an equal amount of samples for differing material or pass types, allows you to selectively increase the amount of samples of each pass. As well, for direct lighting samples, it would sample all lights instead of random lights, resulting in a reduction in noise.
Blender 2.71 adds an additional option to the branched path tracing integrator: it makes the ability to sample all lights for direct lighting optional, and adds an option for sampling all lights for the indirect lighting pass. That second one, when used, does increase render time a bit, but it comes with a substantial reduction in noise.
The image below is rendered with Sample All Indirect Lights turned off, and is a composite of the indirect lighting pass.
As you can see, it is quite noisy. Now, let’s see what happens when Sample All Indirect Lights is turned on.
Still noisy, but the amount of noise is substantially less. Of course, this is just with a low sample count. The Branched PT settings are 2 AA samples, 16 glossy samples, and 1 sample for everything else.
The first image rendered in 3.19 seconds, while the second one rendered in 5.63 seconds, so it was roughly a 75% increase in rendering time. However, the reduction in rendering time required is significantly greater. In order to obtain a similar amount of noise reduction, one would need to increase the AA samples to 8 and Diffuse to 16, which increases the rendering time to 40.46 seconds, an increase of nearly 13x to the rendering time for a small improvement. And that’s just with a small 400x300 image, for something larger (like a desktop size) it’ll take 12-16 times longer, or more.
But with the Sample All Indirect Lights option enabled, I was able to get a 99% clean render in close to the same amount of time (41.63 seconds). Earlier today, I had been working on a noise-removal node for the compositor to get rid of the noise. With this improvement, I can scrap the de-noising node entirely!
This was the result of me staying up until 2:00am while working on a comic update in blender. The first frame for this episode had to be rendered at x4 resolution, as a workaround for the beard on Ianos getting rendered abnormally thick.
This panel depicts all five of the Spell Breakers, shown together in the same panel for the first time since the art upgrade. They’re all walking along to meet with Cyrus Redmane, to find out more about the contract they’ve been offered. Meanwhile, Hassad runs to catch up after he critically failed a booty call: http://lordofmaelstrom.com/content/main/42
Green Uranium in Minecraft
In Minecraft, several mods add uranium ore to the game, and almost always depict it as either green or lime green. I thought this was a little silly and innaccurate, but understandable given the widespread myth that radioactivity emits green light (it actually emits blue light).
However, while randomly browsing on wikipedia, I discovered that several crystalline sources of uranium actually are green! The ones I found were quite interesting:
As well, the first one on the list, Autunite, will glow green when exposed to ultraviolet light. I believe this may be a property of the uranium itself, as the same thing occurs with uranium glass. This is probably also where the myth that radioactivity emitted green light originated, though obviously the myth is still untrue since it typically depicts the light being emitted under ordinary conditions.