Mike_RB
Symek: Thanks for the politeness in your response. But I'm a big boy and I can take it. I guess I'm approaching this from a commercial perspective more than hard-core film rendering. Commercials tend to be a beast as their quality requirements have gotten very high and yet their production timelines have gotten shorter. Combine that with even more work being done in post as an additional day on set is so much more expensive than ‘just fixing it later’. Ease of setup can really be a factor when you have no time.
But I wasn't trying to go for a speed comparison, not even a quality one really. I recorded *what* I setup, so that I could see the same setup in Houdini. I don't really care if its dog slow or way smoother, I would just like to be able to get the same images, with the same types of features in Houdini as in modo. It looks like Steve is close already.
Other than isolating the glass object with a fine shading rate, and adding some more samples to the blurry reflection one this scene would animate relatively well. But again, I don't really care about the speed comparison part, I just want to be able to make the same images.
And I agree, the likelyhood of setting up 5 toroidcubes each with a different material on a white table lit by the standard kitchen HDR for a production shot is remote. 
I haven't run across such a thing yet, not even back on Andromeda. However it would have made a ‘very creative’ alien device.
Glad to hear that. I was little rude because I see number of questions about how to use Mantra like VRay which drives me into madness. If someone likes Modo or VRay why to bother with Houdini which is, at the first glance, different kind of tool..? I know a number of people who recently started to consider working in Houdini exactly because of that difference in kind.
It's pretty difficult to explain what makes this difference (at least for me). At the same time this difference makes many people who made one movie in mental ray (rather decent engine for sure) to runaway from it towards any micropoly engine among which Mantra shines with additional capabilities like volumetrics or PBR (not mentioning its price!). I'm also close to conclusion that raytracing engine in Mantra is the best one among all reyes engines. (The only problem I can see now with it, is instancing - instance, threading, and raytracing is a kind of trio which puts Mantra in shame).
You're absolutely right about time factor in commercials. But studios usually don't start from scratch. They build their tools through years. One of the most important quality of Houdini's workflow is how easily one can accumulate knowledge and tools in it. Like in good OOP, nothing has to be done twice.
Anyways, from my perspective work on your scene implies:
- Houdini doesn't come with energy conservation shaders. If you'd like to use one, you are in charge to make them. Personally I don't see the reason for that, but this is my POV.
- Soft Reflections scream for anisotropic shader with custom pdf (probability distribution function) sent to gather() loop or similar solution. I assume most Mantra/PRMan houses have their own version of such shader. Ask Mario about details
. It's crazy fast and flexible but currently needs to be coded by the user.
- Soft shadows could be done in PBR pass in which they are relatively cheap and stable (raytraced soft shadows like to be ugly). Another alternative is an implementation of depth map soft shadow shader based on Disney paper:
http://www.3db-site.com/html/softShadow.php?568f0b00 [
3db-site.com]
Of course you can use, as many of us, simple raytraced area shadows. The problem is that this solution *in any renderer* really fast reaches its limit in heavy or displaced scenes. Mentioned previously difference is that Mantra gives you a choice to avoid this limit.
- GI workflow in Mantra is a kind of broken pipeline with surprisingly good end. There is pretty nice irradiance() call in VEX with an implementation of irradiance cache based on gradients (Ward 1992(?)). One should isolate that call from other shadings and consider baking its data to pointcloud/brickmap. Again PBR seams to be perfect alternative for that. Unfortunately its introduction apparently broke such nice thing like the photon workflow in Mantra. Personally I use mental ray's Final gathering for baking GI in Mantra
.
All of this doesn't change the fact that irradiance() works pretty nice with baking to point cloud what does make a difference in high res animation. Again pretty extensive setup has to be done.
- As you mentioned in previous post, glass rendering likes to be separated for a fine tuning of sampling. Nice thing about VEX is that it lets you control all attributes of rays on per surface bases (or practically per ray bases). Glass is really difficult to render and I haven't seen many nice moving pictures of glass surface.
As I see this now rendering could be challenging also for planing and considerations. I know a beauty of easy setups since I work often with Vray team. I also know the pain of rescuing actions in case easy setup fails - this usually happens in a most destructive moment of production
.
You can of course make a simple setup like above and count seconds but such blind comparison with VRay or Modo is pointless as we don't even touch features which make Mantra competitive to most respected and expensive engine out there.
cheers,
sy.
PS Sorry for a long post. I'm waiting for rendering
