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Comment by erichocean | Hacker News Reader

Here are some render comparisons for the curious: http://appleseedhq.net/stuff/renderers-comparison/index.html

- I've never heard of Tungsten.

- Mitsuba is a mainly-academic renderer by Wenzel Jakob (I say mainly because I haven't seen its widespread use in non-academic setting).

The two important open source renderers that are missing in comparison:

- Cycles (comes with Blender; produces great results although it is said that it only recently has started doing a "PBR workflow")

- Luxrender (very popular with artists on deviantart; has very good OpenCL support)

That's because the point of the comparison is not to compare with other renderers, it's to check feature correctness. Mitsuba is widely used for that purpose.

Almost no one uses LuxRender or Cycles commercially to the best of my knowledge (or appleseed for that matter). Hobbyists use them, which is cool.

I'm in Los Angeles and work in the industry. Here, people use Renderman, Arnold, and in-house stuff mostly. I don't think Renderman and Arnold are used much outside of VFX. Arnold in particular is pricey, but works amazingly well.

Few people use Blender professionally, but those that do almost certainly will use Cycles. It's very capable now, quite similar to Arnold, but not as fast.

It's still desirable enough that it's getting commercial plugins (cycles4d).

> Here, people use Renderman, Arnold, and in-house stuff mostly.

Disney has Hyperion and Weta has Manuka, although I'm not sure if they license them out to other shops.

> I'm not sure if they license them out to other shops

Not that I know of. Many houses also have specialized in-house renders for voxels and occasionally, fluids.

> Many houses also have specialized in-house renders for voxels and occasionally, fluids

Hella cool! Who is rolling their own outside of Weta?

DD? Animal Logic? Double Negative? Blue Sky is super proprietary, I'm curious what they are up to...

A lot of studios used to have their own fluid / volume renderers, but it's less common these days as the main renderers can do volumes/implicits fairly well these days.

But more studios have their own full renderers these days:

Weta has Manuka

Disney has Hyperion

Animal Logic has Glimpse

Framestore has Van Damme

Sony has their fork of Arnold

Sick! Any idea what ILM is up to, or are they all Renderman all the time now?

Mostly Renderman RIS now from what I've heard, although there's still a bit of Arnold being used, and the VRay stuff DMP were using is mostly Clarisse now.

Tungsten is from one of Wenzel Jakob's former students, I think. He maintains a pretty cool set of models: https://benedikt-bitterli.me/resources/

How am I supposed to compare these three on the top as a non-expert in this area? The middle one looks noisier than the other two. I notice the one on the left has darker color in dresser which may be an advantage of correct, color handing but might be incorrect with one on right being brighter due to the correct handing of window's light on it. And what's up with the graininess of all of them?

Just a few things that popped into my mind looking at them. Wouldn't mind learning a little more in objectively evaluating the renderers.

The color differences are from different "tone mapping" implementations after the render is stopped and can be ignored.

The point of that page is to evaluate renderer correctness (think of them as visual unit tests), not to really compare "which one looks better". For example, some of the images show appleseed with hard shadows, when they should be soft.

If you want to know which one is "right", Mitsuba is the one to look at as it's generally the most correct.

The graininess comes from not letting the machine renderer longer—the longer it goes, the less grainy it will be. That said, all of these renderers employ "tricks" to reduce the graininess that can make it practically impossible to remove whatever graininess slips through.

You can't say any of these is "more correct" from looking at the renders. Those hard shadows stem from a difference in light size, which is almost certainly a problem with the scene parameters being treated differently. The light size may have been "lost in translation", turned to 0, creating a perfectly sharp shadow.

One limitation of appleseed today is that our physically-based sun model is a purely directional light, not a far away disk with a finite radius. This explains the hard shadows on some of the scenes.

> And what's up with the graininess of all of them?

I am not a rendering expert either but IIRC "physical rendering" works by shooting photons across the scene based on a random distribution, and in the end, the finished rendering is an average version of all photon passes. If you don't shoot enough photons, the averaged out version will be noisy because there will be some hotspots were significantly more photons hit, relative to the total photon count. More photons = longer rendering time, so the graininess is in the end probably caused by a time constraint enforced for each of the images.

Typically, it's not using photons but the other way round, paths are started from the camera primarily.

The noise stems from the simple fact that those renderers try to solve an infinte dimensional integral (all light reflected by all surfaces) with stochastic Monte Carlo methods, the most popular being path tracing. There are other methods (finite element radiosity for example) to simulate light transport that do not exhibit stochastic noise, but those have fallen out of favor.

Without knowing the settings which were used by each renderer (and thus stuff like the BSDF materials, sampling techniques, random number generator sequences, etc, etc), it's very difficult to say.

All these things play a crucial part in how efficiently a renderer can produce an image with as little noise as possible.

But it's also possible to look through the noise (ignore it), and look for issues - i.e. the Classroom scene is very odd as Appleseed doesn't have soft shadows (what light type was used? PhysicalSky/Sun? HDR IBL?), and the Tungsten illumination from the environment is less warm.

The classroom is lit by a physical sun+sky combination. A limitation of our current implementation of physical sun is that the sun is a directional light instead of being a far away disk of finite radius. This is why we don't have soft shadows in this scene.

In theory, for "unbiased path tracers", the results of all three should be the same, at infinite samples. Rendering for a finite amount of time, lower noise suggests the renderer is more efficient.

In practice, every renderer has different features and settings, so the actual scenes will only be approximately the same.

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