【Level Of Detail】

　　Here‘s one of the ways to set up an object with different LODs.

　　At this point the empty object should contain both versions of the mesh and "know" which mesh to show depending on how far away the camera is.

　　按上述设置完毕后，这个空对象就知道距离Camera多过远的时候该用哪个Mesh了。

[Auto create LODGroup]

　　In order to simplify setup of LODs, Unity has a naming convention for models that are being imported.

　　Simply create your meshes in your modelling tool with names ending with _LOD0, _LOD1, _LOD2, etc., and the LOD group with appropriate settings will be created for you.

　　Note that the convention assumes that the LOD 0 is the highest resolution model.

[LOD-Value]

　　Models which have a LOD below the MaximumLOD level will not be used and omitted from the build (which will save storage and memory space). Unity will use the smallest LOD value from all the MaximumLOD values linked with the quality settings for the target platform. If an LOD level is included then models from that LODGroup will be included in the build and always loaded at runtime for that LODGroup, regardless of the quality setting being used. As an example, if LOD level 0 is used in any quality setting then all the LOD levels will be included in the build and all the referenced models loaded at runtime.

　　The idea with shader LODs is that it enables you to enable/disable various graphical features:

• Each shader has an LOD
• You can specify that shaders above a particular LOD will be disabled

参考：

1、http://game.ceeger.com/Manual/LevelOfDetail.html

2、file://localhost/Applications/Unity/Unity.app/Contents/Documentation/Documentation/Components/class-QualitySettings.html

3、http://answers.unity3d.com/questions/330839/what-does-the-lod-value-for-shaders-represent.html