Lods having its own normal maps ?
polycounter
I see many rock objects in megascan have each own normal map texture for each lod level. Is it a common practice nowadays? Just wonder because I always tried to do it look ok with a same single normal map for all lod levels. it makes a lot of pain in your a... although . So having a new normal map for each lod looks like an easy fix.
Replies
I've worked on some projects where LODs would have different normal maps. The most common is having something like a first-person view weapon model and a third-person version with a lower resolution texture and rebaked normal map.
In any case where the geometry differs significantly, a different normal map could make sense. But I'm not sure how common this is in practice. I image with LODs being auto-generated much of the time, unique normal maps are rarely used.
Depending on the number of LODs you have, the number of unique textures needed can get out of hand quickly. Plus, at the distance that LODs are viewed, the size on screen and mip level is going to be so low that you probably wouldn't notice it in many (most?) cases.
For something like Quixel Megascans assets, it makes more sense. You're probably going to pick a detail level appropriate to your project as the base content, so having normal maps for each pre-generated LOD is useful.
For assets like really big rocks, normal maps for LODs can be useful, but one for every LOD level is overkill. Currently I'm working with a bunch of big (100m high) cliff meshes that have a low res normal map specifically for the last LOD.
Thanks guys . I am working at some 20m high cliffs from lidar laser scanner. With hard /split edges the lods are usually is lesser of a problem since vertex normals stay in same direction usually . But because of number of reason I had to go all smooth and face weighted normals and when it came to lods the whole thing looks alive now :( Everything is twitchy . Had to manually rotate gazilion of vertex normals now since regular attribute transfer is not that great too.
Couldn't you pick LOD2, use that to bake the normal normal maps, and transfer the normals to the other LODs? Seems like it should work well for a large rock.
That's more or less what I'm doing, yeah. For technical reasons the lowest LOD has to be so heavily decimated that it needs its own UV unwrap and normal map.
I use Maya's transfer attributes without issue - is that what you're using? You want to transfer from lower to higher. You may have to manually fix the occasional vertex, but it shouldn't be a big issue.
Yeah, it's what I do too as a general rule for any kind of object for more than a decade already but for the big rock wall it's getting too few vertexes further ahead after lod2 . So it should be lod3 probably . For some uncertain reason data transfer in Blender (it's what I use ) , actually "capture attribute" node from its construction nodes does too many errors .