and this is 520 triangles:
To have this much detail is a brute force and overkill way to get the distribution of samples that you really want on a sub pixel level, but sometimes these things are done in film because with a lot of pain you can make it work.
In this case if they did actually do that, it is through instancing, which in a sense could be thought of as a lookup with polygons to ultimately get that distribution. Usually a huge amount of samples are needed to deal with aliasing as well.
> Every shot in Piper is composed of millions of grains of
> sand, each one of them around 5000 polygons.
I'm guessing the article is just confused. The important point, I think, is about using real geometry for sand particles rather than the beach being a surface with a displacement map.
I'm not ashamed to admit I teared up a bit at how good it was.
They also mention that, "this result was driven by a combination of culling techniques including camera frustum, facing angles and distance, creating a variance of dense to coarse patches of sand for optimum efficiency."
So while they had grains each of ~5000 polygons available to them and positions that they could occupy, they cut down on that polygon count using a combination of techniques (many common in games too) to make it all work. So the polygons of any grains outside the camera frustum were ignored. The faces of the grains point away from, I presume, any light source and therefor not contributing to the path tracer were ignored and also some soft of LOD to reduce polygon count as distance.
As an amateur blender user I'm reminded of microdisplacement as a way for us mere mortals to achieve something in this space:
Didn’t understand most of it, but it is a jaw-droppingly beautiful short, and the stills in the article are well worth the skim.
On the VFX side of the industry we were often jealous of Pixar and Dreamworks being able to do shorts, in terms of having the scope and ability to test out new tech / pipelines.
Pixar was the last holdout for maya, they only converted in the last few years