Raploz
Member
Those super detailed movie quality models can actually be smaller than traditional low-poly models + LODs + 4K normal maps. Yes, you read that right!
I was reading the UE 5 documentation and there they compare the size of traditional models (plus normal maps and LODs) to Nanite models with millions of polygons. Apparently the normal maps used in current games can be bigger in size than a movie quality Nanite model. Quoting them: "Because the Nanite mesh is very detailed already we can try replacing the unique normal map with a tiling detail normal that is shared with other assets."
Here's the link (go to the section "Data Size" to see the full size comparison and images): https://docs.unrealengine.com/5.0/en-US/RenderingFeatures/Nanite/
I was reading the UE 5 documentation and there they compare the size of traditional models (plus normal maps and LODs) to Nanite models with millions of polygons. Apparently the normal maps used in current games can be bigger in size than a movie quality Nanite model. Quoting them: "Because the Nanite mesh is very detailed already we can try replacing the unique normal map with a tiling detail normal that is shared with other assets."
Here's the link (go to the section "Data Size" to see the full size comparison and images): https://docs.unrealengine.com/5.0/en-US/RenderingFeatures/Nanite/
Because of the micro detail that Nanite is able to achieve, it might be assumed that it means a large increase in geometry data resulting in larger game package sizes and downloads for players. However, the reality isn't that dire. In fact, Nanite's mesh format is significantly smaller than the standard Static Mesh format because of Nanite's specialized mesh encoding.
For example, using the Unreal Engine 5 sample Valley of the Ancients, Nanite meshes average 14.4 bytes per input triangle. This means an average one million triangle Nanite mesh will be ~13.8 megabytes (MB) on disk.
The compressed package size isn't the entire size of the asset though. There are also unique textures only used by this mesh that have to be accounted for. Many of the materials used by meshes have their own unique textures made up of different Normal, BaseColor, Metallic, Specular, Roughness, and Mask textures.
This particular asset only uses two textures (BaseColor and Normal) and thus is not as costly on disk space as one with many other unique textures. For example, note the size of the of the Nanite mesh with ~1.5 million triangles is smaller in size (at 19.64MB) than a 4k normal map texture is.
The total compressed package size for this mesh and its textures is:
Because the Nanite mesh is very detailed already we can try replacing the unique normal map with a tiling detail normal that is shared with other assets. Although this results in some loss in quality in this case, it is fairly small and certainly much smaller than the difference in quality between the low and high poly version. So a 1.5M triangle Nanite mesh can both look better and be smaller than a low poly mesh with 4k normal map.
- Low Poly Mesh: 31.04MB
- High Poly Mesh: 49.69MB
Total compressed package size for the Nanite-enabled mesh and textures: 27.83MB
Comparing the Nanite compression from earlier with a size of 19.64MB is 7.6x smaller than the standard Static Mesh compression with 4 LODs.
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