Are image quality metrics adequate to evaluate the quality of geometric objects?

Geometric objects are often represented by many millions of triangles or polygons, which limits the ease with which they can be transmitted and displayed electronically. This has lead to the development of many algorithms for simplifying geometric models, and to the recognition that metrics are required to evaluate their success. The goal is to create computer graphic renderings of the object that do not appear to be degraded to a human observer. The perceptual evaluation of simplified objects is a new topic. One approach has been to sue image-based metrics to predict the perceived degradation of simplified 3D models. Since that 2D images of 3D objects can have significantly different perceived quality, depending on the direction of the illumination, 2D measures of image quality may not adequately capture the perceived quality of 3D objects. To address this question, we conducted experiments in which we explicitly compared the perceived quality of animated 3D objects and their corresponding 2D still image projections. Our results suggest that 2D judgements do not provide a good predictor of 3D image quality, and identify a need to develop 'object quality metrics.'