Sentence:  Graphical level of detail (<WSD>LOD</WSD>) is a set of techniques for coping with the issue of limited computational resources by reducing the graphical detail of the scene far from the observer. Simulation <WSD>LOD</WSD> reduces quality of the simulation at the places unseen. Contrary to graphical <WSD>LOD</WSD>, simulation <WSD>LOD</WSD> has been almost unstudied. 
Meaning of the word marked with <WSD> tags:  Level of detail.