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Level of detail

“Level of details” by Wojtek “Buddy” Starak
UV MAP
UV maps should also be optimized, there are several tools for this but anyways most of the work needs to be done manually… which means it can be done more precisly. Uv maps should be as tight as possible, have as less free space left as possible and there should be a little gap between several pieces to fix mipmapping issues which may occure. UV maps should be normalised in most cases, which means all segments should share proportions with the model, this means that they should have exacly same sizes like they have on model. But there are exceptions, mostly for weapons, it’s same as with poly count amount in certain places depending on distance to eye… if there’s a iron sight option in the game it would be good if the gunsight part have higher res texture than end of the barrel for example. This means that parts which we see closer or often should be bigger on UV than the parts we see rarely or on higher distance.

NOTE: To check this, apply „Checker” Material to a Model and look at checker squares, if they don’t have exacly same size on all polygons this means that UV map isn’t normalized (bigger squares=higher res/bigger UV segment, smaller squares=lower res/smaller UV segment), if squares are stretched it means that UV of those polygons have incorrect shape.
I personally try to avoid overlapping because it makes two places on model look the same but unfortunatley this optimizes. It works on models when some parts of it can share same place on texture.
Example:

model

good uv

good but overlapped uv (top and bottom of the model share same space on texture, shown as red on rendered UV). It’s half smaller (256×256) than on pic above (512×256).

wrong uv (notice ugly overlap of sides and how they are placed, much free space=bad)
More information about UV maps, several tool whereabouts etc You’ll find in a tutorial which is arleady in production and should be relased soon.

Someone invented a LOD system …
Lod – Level of Detail- used in games, it’s a set of variations of a same model with diffrent amount of detail, in most cases lod 0 is model with highest polycount/detail and higher values means lower polycount/detail. They often are set to a distance from player and/or parented to game video settings (both are in Half-Life 2). It is essential for a good model that it is well optimized even on it’s highest polycount LOD. (LOD system is very simmilar to mipmapping)
If we decide to have, like in example, our mug to have a little more detail, we can create several lower detail models which will replace the higher poly one on distance. If we have a 8 segments and 6 sides mug, we can reduce it on 10 meter distance to, for example 6 seg and 4 sides, it’s hard to notice small changes like this. But we need to be carefull in creating LOD models, we need to keep in mind that those models need to switch without players notice, so it’s very important to keep basic shape outline, you can delete small details, like screws etc. Keep in mind that some of the first lods might be used at closest distances if video settings are changed. Ex: lod 1 can be viewed as lod 0 if video set to medium detail. So You need also to keep in mind that players with lower end hardware don’t want to see leaks in model or bigger parts missing, so it’s better to delete really small things and simplifi bigger ones (like mug handle sides amount). It is prominent to keep UV coordinates same for all LOD models! If the texture will move during the change to lower polycount mesh it will be really ugly and noticeable effect. Try to keep all LODs UVs same, to check if they match each other simply place them next to another and compare. If they all look the same texture-wise it means that UV coordinates are same on all models.

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