Level of detail, LOD, techniques can be a useful tool to maximize scene efficiency and provide maximum throughput of geometry, while also providing other benefits. The idea behind LOD is to provide multiple versions of a model to the renderer.  Now, it can decide to use one or more of the models based on quality and efficiency considerations. This can reduce the memory footprint and time required to render the object. Level of detail is especially relevant for very large, complicated, models and in situations where many characters or objects are running around. In a shot of a crowd, characters up close to the camera will have sufficient intricacies, while on a distant ridge a much simpler model can be substituted for the character. 

• Models of different complexities can be substituted during certain ranges, measured in pixels.
• Versions of a model must be blended together, to provide seamless transitions.
• LOD increases scene efficiency and decreases render times, by minimizing memory footprints. 
• Reduce aliasing artifacts by using models with appropriate detail for their size.

With MTOR you can attach level of detail attributes to groups of objects.  Here's the basic workflow:

1. construct several (3 or 4) versions of your model
2. group them under a single grouping node
3. attach MTOR LOD Control attributes to the grouping node
4. attach MTOR LOD Detail Range attributes to the top node of each model version
5. assign a Slim Archive appearance to the top node of each model version