Automatic synthesis of simplified three-dimensional models from detailed data
Modeling and displaying complex objects in Computer Graphics often requires using multiple levels of detail for display practicality and efficiency. We develop a computational scheme for automatically constructing a hierarchical representation of successively more detailed 3D object surfaces, given a 3D object represented as a connected network of surface points. In our scheme, successive levels of object representation provide progressively detailed descriptions of the object. Thus, each object is represented in a hierarchical format with gradually improving detail. Dynamic models with global and local deformations were adopted in constructing the hierarchical representation for their reliable recovery procedure and complexity control process. The models can capture the prominent shape of the object with a few global parameters while their local deformations can represent the detail of the shape. We develop a locally adaptive subdivision technique for finite elements to increase representational efficiency and accuracy in recovery of the dynamic model. With locally adaptive finite elements, we were able to obtain a better fit to the 3D data with significantly fewer elements than with non-subdivided elements. We construct a smooth hierarchy of object details of complex 3D input object by applying progressively refined deformations to the dynamic models: first by applying global deformations only, then global and local deformations, and finally global and local deformations with various levels of locally adaptive subdivision. Based on the constructed detail hierarchy, a rendering system is able to display objects at various detail levels, depending on the viewing transformations or user-specified importance. A display mechanism employs a metric based on the screen area of the object which is used in selecting the appropriate level of detail. We develop an area metric threshold (AMT) predicate in order to determine the threshold values of this metric for each level of description in the hierarchy. We show that our object detail hierarchy affords substantially more efficient rendering than full detail data sets.
Koh, Eunyoung, "Automatic synthesis of simplified three-dimensional models from detailed data" (1993). Dissertations available from ProQuest. AAI9413863.