PIXAR :: Technology Focus

#81

Interesting technology. There is a little more detail about it here:

http://features.cgsociety.org/story_custom.php?story_id=3889

#82

just saw that a lot of this is beeing discussed in the previous pages. Mauritius actually explains things very well and Simon too mentions the difference between raytracing and shader execution which really should be treated as two seperate things.

there are some related articles in the pixar research group (haven’t seen them posted here)

Some infos about raytracing in renderman (already a few years old)
http://graphics.pixar.com/library/RayTracingCars/paper.pdf

An updated paper about point based gi techniques. you really get some nice information here:
http://graphics.pixar.com/library/PointBasedGlobalIlluminationForMovieProduction/paper.pdf

what make me think that renderman is a fast raytracer is not necessarily that in a 1:1 comparison renderman would win against others like vray and mr. its also very difficult to create test scenes which do not favor one of them. the huge difference is that I am the one controlling raytracing in renderman while mr and vray just do their thing

point based soft reflections/refractions for example is something that can be used in some very specific situations and fails in some others. in my shaders i can switch between different methods and thus i can highly optimize my scenes.

with a good message passing system in the raytracer as it is implemented in renderman allows you for example to distribute important information with your rays with which you can improve your filtering on ray hits thus reducing variance.

keep in mind that on high quality productions we are often rendering smooth objects with displacements, fur, etc. even for the ultimate raytracer this means a lot of work and it just doesn’t make sense that one can’t control the tracing behaviour. in renderman you have a lot of control to reduce complexity where its not needed

summing this up gives you the tools needed to reduce and optimize tracing and shader execution to a minimum and this is what makes me think renderman is a fast raytracer

think of it, it doesn’t matter what renderer is used as long as it gives you the control you need. for some productions is may be that vray and mr give you all you need and they do give you beautiful images. however i don’t think that they give you enough control for productions where directability has very high priority. the only rescue then is to change the look etc in post which isn’t always ideal. in renderman i can fully control the look in 3d while i too can output any amount of aovs (“passes”) without slowdowns and refine in post.

so why isn’t everyone using renderman, right? thats pretty easily answered. first of all the majority here on cgtalk for example isn’t using renderman. new users facinated by your renderings always hear mr and vray and thus this is their first choice.
but what i think is the main issue is that not everyone can just hit some buttons and get the image they want from renderman. the amount of settings and controls which on one hand give you control on the other hand confuse new users. so it really needs some time to get used to it. what highly complicates this issue is that there is very little good information about renderman renderers. a lot of comments here show that a lot of users tell things that are simply wrong. rumors and misunderstandings quickly spread when there isn’t enough information available.

grs
Patrik

#83

very intersting about raytracing

I had a commercial 6 months ago where i felt i had to switch to MR because the client wanted a delicious looking hard candy/boiled sweet…i.e. Lots of blurry refraction, reflections, sss, etc.

I use RfM and my rendwrs were long. interestingly, they originally wanted chocolates and RfM was amazing. I was cranking out 4k previews in 50 seconds a frame.

But after they switched candies on me i was waiting and hour a frame at 4am…and i bit bullet and tried MIA X in maya.

Way fast but i lost my cool DOF and moblur.

Anyone have any ideas how to optimize such a render? i dont like moving back to MR.

Im commuting now, but ill post the scene if anyones intrested

Thanks

#84

Well, mental ray is included with 3dsmax, Maya, Softimage, and also some cad tools use mental ray’s engine, so mental ray is automatically going to be used more than PRMan. You aren’t going to hit a few buttons and get a great rendering out of mental ray or V-Ray either, there is a lot to learn with both. V-Ray simply is easier to get global illumination looking excellent in very little time due to irradiance/light cache calculation method and very fast soft shadows.

#85

hi scott,

this is exactly what i meant! a lot of users feel the same as you do and especially when there is pressure from tight deadlines its suddenly a logic choice to get back to what one is used to. switching from mr/vray to renderman really takes some time and can get frustrating because things don’t work as they used to.

its not really possible to tell what is causing the slowdown in your scene without having the details. if you want me to i can have a look at your scene. just PM me and i’ll check what i can do about it. however the best place for such things is the renderman support forum. you’ll get pretty experienced feedback there and its also a great ressource. when i started with renderman i actually read through nearly the whole forum. this took quite some time but really gave me a boost.

@scottsch
did you ever try GI and traceable deep shadow maps with RPS16? its amazingly fast!

grs
Patrik

#86

yeah its really useful and i will make share for it :wink:
thanks & regards
Tarek

#87

If you upload the scenes, I can do some tests with RMS 3/ RPS 16 to see if the new speed improvements in pro server and the ap shader workflow would help you cut down render times.
I’ve rendered some very glossy reflections in acceptable render times. With some slight hacks of course, but that’s the nature of the software…

#88

hey you guys i appreciate that…ill have to dig through some files to find the right one…had like 30 versions of this incredibly simple scene …lol…ill get back with that in next coupla days

#89

Renderman is dead, or on its way to die!!
http://forums.cgsociety.org/showthread.php?f=2&t=992895

#90

i’ll just answer here. i fully understand your frustration. mr and vray usually have a i would call “one-algorithm-solution” to problems. renderman always offers several methods. one algorithm works in a specific situation but may produce artifacts in other so its really up to the TD to choose the right algorithm and this does need more time in some situations. however experienced TD’s are capable to handle such situations without problems.

sure manpower is much more expensive than cpu time BUT there are other factors to keep in mind. some optimizations are implemented very quickly but reduce rendertime significantly. there are scenes which are not possible to render without the right kind of optimizations. every raytracer suffers the problem that its build to hold the geometry in memory. arnold for example uses for 300mio tris about 14GB of ram. sure thats pretty good but this is putting a limit to your production. what if you really need more? also this scene with 14GB was geometry only without textures, volumes, no motion blur, etc what would be more probable in a real production.

arnold is very very sophisticated and i too will have a close look at it but if you look at what gets implemented in prman every year its getting more powerful too in aa amazingly fast pace.

raytracing will become more and more important. have a look at the release notes of prman from the last years. they are adding more and more to the raytracer and i’m sure the next versions will too follow this direction. however raytracing will stay a tool and won’t become the solution! there are so many situations where cheaper methods produce good results and there is no reason not to use them! raytracing is kind of a brute-force method which gives you correct results but is inefficient and wasteful with ressources.

for this i really disagree that prman was going to die! prman exists much much longer than vray and mr and I’m sure it will stay much longer than them aswell especially in high quality film production

grs
Patrik

#91

really a good informative article by cgsociety

#92

“Because of the extreme complexity of certain shots these point clouds can still be over a whopping 300 gigabytes, and generating the same effect on these types of datasets is just not possible with ray tracing or radiosity methods, because of the higher memory cost.”

Wow I didn’t realize that what was done to create Speed Racer, Cloudy w/Chance of Meatballs, Tron Legacy, Real Steel and Green Lantern was “impossible” much less “not viable”. These all had full cg and/or photoreal feature quality rendering with radiosity, and no point clouds. They also didn’t need terabytes of extra drive space, hundreds of man hours debugging point clouds, and more, higher-priced labor, all for a lower quality result. Point clouds and ambient occlusion cannot match raytracing accuracy, and the difference would be visible to anyone if they were shown side-by-side examples.

You may think it’s impossible after listening to Renderman people, and that’s because in one context, it is true; using raytracing for everything in Renderman is not the least bit viable. The last time I tested it, rendering the exact same Maya scene in Mental Ray and Renderman, the score was (MR), 4 seconds and (RM), 17 … wait for it … minutes. A plain lambert shaded character with 12 raytrace shadow lights, no soft shadows, low quality settings, 1024x786. Apparently the latest version of Renderman is 4 times faster at raytracing, but 4 x faster than 17x60sec. is about 250 sec., against 4 sec. with Mental Ray, it has a lot further to go.

Renderman definitely has it’s strengths, it’s handling of tons of geo and textures, displacement and motion blur are hard to beat, but the photorealism is only ‘good enough’ to fool the average movie-goer - some of whom thought Beowulf had live actors. Just look at stills from the latest Pixar movie - do they really look like real miniatures? Of course not, and Pixar isn’t worried about that, they’re more interested in the overall look, and they do look great, and maybe that’s why they put reasonably fast raytracing on the back burner.

#93

sorry, but a lambert shaded character has nothing to do with a production like renderbenchmark.

#94

Pixar Pixar Pixar Pixar Maya Maya Maya Renderman Renderman Renderman Pixar Pixar Pixar Pixar Maya Maya Maya Renderman Renderman Renderman Pixar Pixar Pixar Pixar Maya Maya Maya Renderman Renderman Renderman…

Pixar is awesome
Pixar is amazing
Pixar is sublime
Pixar is God
Pixar is Goddess
Pixar is everything

Without Pixar world would split in two. Without Pixar hungry people couldn’t found anything to eat. Without Pixar there wouldn’t be peace in the world. Without Pixar there wouldn’t be time & space & quantum physics.

…

And remember as ALL the production articles on the internet says the same thing over and over; “that sort of huge animation productions is not for faint of heart”

LOL

#95

WETA is using pantaray with renderman. pantaray for raytracing
http://www.fxguide.com/featured/tintin-weta-goes-animated/

would it be possible to render Avatar,TinTin and Rango with a 100% raytracer at the same time and money?

#96

You can’t have a mocap equipment without Andy Serkis packed with it. And remember VFX is not for faint for heart!

#97

to answer this you have to know which parts of the shots of rango for example are raytraced and how much of the scene was visible for the rays. also, how complex was the reyes generated geometry (and shading effects) so you know how much you have to trace. but i am not sure if someone will answer, perhaps you get the same answer like for avatar and for this, it would not be possible to trace all the stuff like reyes need to render. would be great to get some more indepth informations here. :wink:

#98

I was testing raytrace shadow speed, not overall speed, so I didn’t use textues. Personally I think that comparing overall speeds, when one traces and the other does not, is pointless, unless they look identical. Speaking of which, the time it takes to render shadow maps and point clouds (and re-render if anything changes or is broken) is almost never included in the comparisons. It was a feature film production model w/ half mil polygons, bigger and more complex than a human, if that makes any difference. I also noted that in a (production) scene with several spotlights, switching just one of them from shadow map to raytrace would double the rendertime.

Nobody thinks that renderman (and by that I mean PRman, Renderman itself is not software, only a specification) raytraces as fast as others, it’s not designed from the ground-up to trace as the others are, and as far as I can tell they are so biased against tracing there’s no way it’s a priority for them.

Pixar has created some amazing technology, like motion blur that renders about as fast as no motion blur, point clouds got them an Emmy - why they throw out the baby with the bathwater when it comes to raytracing is beyond me - but maybe it really is because they don’t have the need to do or the experience with live action rendering, and don’t care if their work is photoreal.

The reason motion blur is so fast in PRman is because anything that will be blurry is dropped in quality at rendertime. If you’re willing to lose a little more realism, it can even render faster with motion blur than without. So why on earth do they simply say “raytracing takes too long to evaluate shaders multiple times and needs too much memory” when they could simply do the same thing - use low-res geo and textures, no displacement or subdivision, and ignore everything in the shaders except diffuse and maybe spec/reflection - and end up with a better looking render?

#99

You cant just ignore stuff when using raytracing… You cant just ‘drop’ displacement, for example. The whole point of usig raytracing is because its more detailed.

#100

They don’t use PRman afaik, I know ILM does not, they use their own implementation of the renderman spec and their own raytrace code. When you consider the downsides to ambient occlusion and point clouds, yes it’s quite possible it could be done as fast in a raytracer as you could in PRman. But fast & cheap are not the greatest things to judge renders by :slight_smile: Raytraced images would look far more real. These look like paintings by comparison :
http://images3.wikia.nocookie.net/jamescameronsavatar/images/5/5f/Valkyrie.jpg
http://www.zastavki.com/pictures/1280x800/2009/Movies_Movies_A_Avatar_ship_019167_.jpg

If the dozens of brilliant people at Weta or ILM decided to use a raytracer, there’s no way they’d fail at it. Renderman became the established tool because machines used to be slow and low on ram, but that’s all changed. When computers double in speed and ram yet again, will they still be saying raytracing is too slow?