Ok, returning to my initial question, just how much more detailed is Thanos in Endgame compared to, say, Kratos in the new God of War? Gimme numbers on those polycounts and material resolutions.
In terms of raw numbers, films generally use "UDIM" textures which basically means multiple UV tiles per model, in game terms you can think of a UV tile as a single texture, since games generally only use a single tile (unless they're laying out the UV islands across tiles in which case the texture generally just repeats rather then the game loading an entirely new one).
How many UV tiles? Well, some films are known to use quite literally
hundreds of 4K tiles per hero asset (characters etc). the software Mari is generally used since it's designed to handle that level of texture resolution, alongside really beefy workstations.
(Or if you're Disney, "PTex" textures which is a non human readable format where each face gets it's own UV island which removes to stretching artefacting that normal UVing gives you. Same level of resolution applies though.)
In terms of polycount, this can actually be slightly surprising. Films generally use subdivision surfaces nowadays, which you can think of as an advanced form of tessellation that takes a low poly mesh and then smooths out the raw edges by adding more polygons:
Something that sets this apart from standard tessellation in games is that the result is predictable - a cube subdivided will always become a smooth sphere with enough levels of subdividion. Because of this models in films can actually be fairly low poly to begin with:
(I think this was from Toy Story 3?
Here's the article they were from.)
Once loaded into the renderer however the models are generally subdivided to a level where there's more polygons then there are pixels, then displaced using displacement maps to create more complex shapes that mimic say, the Zbrush sculpt. In many cases this means not using normal maps, but rather just having enough polygons to model the pore level detail itself directly. So the end result is multiple orders of magnitude more polygons then what the artist sees in the viewport.
Pixar actually released a video showing how they use subd surfaces which contains some actual film assets, if you're interested:
And to get an idea of the level of detail we're talking about, a while ago Disney released the
background assets for the Island in Moana for free for background purposes. The data for just that one shot comes out to be around 100GB, and there is
an interesting blog post where someone tries to actually render that data at home - the end result is slightly different owing to the lack of additional lights and the proprietary engine that Disney use, but they still managed to get fairly close. This isn't even close to real time though, they had to disable a significant amount of geometry to even get it to render on their PC without it instantly crashing. and using a render farm they managed to render the whole scene after 3.5 hours at less then HD resolutions. So yeah, games still have a long way to go.
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