Pixar point clouds in maya

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Old 06 June 2010   #1
Pixar point clouds in maya

Hi all render artists.
I was reading this article http://features.cgsociety.org/story..._id=5615&page=1 about pixar new solution for point based rendering.
I wonder if there is any way in maya_mentalray to have an almost similar result .
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Old 06 June 2010   #2
Do you mean being able to see photons and Final Gather points?
there's a utility that loads those maps into your workspace ...
Old 06 June 2010   #3
dneg has a nice opensource ptc for maya plugin on github
Old 06 June 2010   #4
I think he's just looking for point cloud based renderings in maya/mr, as on the other side best solution would be simply to have prman for maya ;-) Btw, both have nothing todo with GI or FG pre-calc points.

However in mray there's a crucial issue that puts pcloudz not as a natural extension to mray tool set (at least for the above pixar approach).. in prman you have micropoligons almost for free .. while in mray not. I still have to see what kind of results we can obtain with 'ordinary' meshes .. following is a pcloud surfel implementation ( points with a radius as the underlying tri area ) on mray.

ciao, max
Old 06 June 2010   #5
Thats intersting Max. And is it possible to use those pointcloud information to generate things like AO or color bleeding effects?

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Old 07 July 2010   #6
well yeah, that's the goal. for AO we have already everthing we need for a bruteforce approach, kind of element-to-element approach. for color bleeding instead we need to bake irradiance to the points to have a chance to get some bleeding effect. For both however would be preferable to have some kind of acc structures for faster lookups. That's what I'm working on actually.

ciao, max
Old 07 July 2010   #7
here a mr point cloud with irrad baked into, ie. diffuse illum + shadows.

From here would be easy to go on, however going to use that raw pcloud just for test, as shading map .. you see what's the problem.. artifacts coming from poor tessellation (around half milion tris, ie. points).

Here instead rendered with a pcloud up to 3mil points .. interpolating a bit over the point lookup. et voilà. :-)
(black spotchies are bad geometry, no overlapping tris !! which is anyway a req for any pcloud or lightmap render approach).

I think I'll gonna try an sss impl.. a funny one is simply to use a rapid falloff for the point map as for lewis&borshukov approach but on point cloud lookup directly.

ciao, max

Last edited by MaxTarpini : 07 July 2010 at 03:17 PM.
Old 07 July 2010   #8
I'm keeping an eye on this thread!
keep us updated max.
Old 07 July 2010   #9
Red face

hi, had some time to refine displace and surface approx support as most of the time micropolys are needed to get fine details from pclouds. so I changed subject .. and I applied to a body model a fine displace noise just to test micropoly support, around 25mils. as the overall base model is not offset by the diplace I just render the pcloud with displace data over the base mesh (750k polys).

took a couple of mins to bake the displaced mesh, while the render of pcloud only (the image above, where the pcloud is used as shading base) takes 20secs with minimal ram use. pclouds itself is around 1gb.

ciao, max
Old 07 July 2010   #10

ok, here mr point cloud subsurface scattering implementation ala pixar.

here I use a coarse point cloud just for test (around 100k points). 25secs for pclouds generations (irrad and sss), 16 sec for the final render (1300, 1000). take care that this is 3D baked SSS (on the pcloud) and as long objs pos and lights do not change, one can re-render just the baked sss with no extra time than the map lookup (of couse the detail is related to the pcloud density).

ciao, max

Last edited by MaxTarpini : 07 July 2010 at 06:27 PM.
Old 07 July 2010   #11
Would love to see a step-by-step tutorial on how to achieve this with Mental Ray & Maya. So if anyone knows how-to I would appreciate the thorough explanation in the end.

And, nice results. So..

now, another question:
Is it worth it? (usable for animation?)
Old 07 July 2010   #12
max, that's peachy!
any chance to have a public shader for this?
my mental ray book my website
Old 07 July 2010   #13
Well 'pclouding' as for this approach needs a whole set of tools, a workflow, to be consistent. That's not really a one-button solution. And I have also the feeling you need to be introduced quite a bit to that. We'll see maybe something of that while dev'ing the toolset. Of course I'l consider some betatesting at some point, and for that you're already on the list !

ciao, max
Old 07 July 2010   #14
fyi: 3delight has full point based occlusion, indirect diffuse and subsurface scattering, and the first license is free.

Also i'm pretty sure renderman for maya supports it, I know renderman studio does.
Old 07 July 2010   #15
fyi: that's just trivial at this point going to support ao and bleeding for mr pclouds. Plus I've already support for prman ptc .. so one may create a pcloud with 3delight and render it with mentalray.
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