As interactive graphics become more common in a widening range of application domains, the need for ``efficient'' geometry is becoming more urgent. Very often, geometric models are either crude approximations that are unsuitable for serious analysis, or extremely complex databases produced by automated systems. Neither of these types of models are useful for real time applications, for a number of reasons.
Very simple geometry has become popular lately through its effective use in PC applications, games, and even in high-end military simulators. Texture mapping is usually used to produce fairly realistic visuals while keeping the overall polygon count low. However, in order for this technique to work at interactive framerates, the textures must be kept simple (low color and pixel resolution), or specialized texture-mapping hardware is required. Even if these constraints are met, the lack of actual geometric detail is obvious upon anything more than a cursory inspection. And, if manipulation of portions of the geometry is required (for ergonomic analysis, or virtual reality interaction), these crude models are completely inadequate.
At the other extreme, detailed geometry is often overwhelming. CAD systems usually create objects with intricate details; when these objects are exported for use in real time systems, even small features can require hundreds or thousands of polygons. Even the most sophisticated workstations available will quickly grind to a halt when confronted with such a model.
Therefore, there exists a pressing need for tools that will remove unnecessary detail, while maintaining the critical, characteristic features of the object. Of course, these features are task-specific: a detailed dashboard may be essential for a driver visibility simulation, but it is completely superfluous if the car is only being seen from the exterior. Thus, it is also important that this tool have a flexible user interface that allows the user to selectively simplify nonessential regions and maintain control over every aspect of the process.