Perceptual issues in substituting texture for geometry

An important goal in interactive computer graphics is to allow the user to interact dynamically with three-dimensional objects. The computing resources required to represent, transmit and display a three dimensional object depends on the number of polygons used to represent it. Many geometric simplification algorithms have been developed to represent the geometry with as few polygons as possible, without substantially changing the appearance of the rendered object. A popular method for achieving geometric simplification is to replace fine scale geometric detail with texture images mapped onto the simplified geometry. However the effectiveness of replacing geometry with texture has not been explored experimentally. In this paper we describe a visual experiment in which we examine the perceived quality of various representations of textured, geometric objects, viewed under direct and oblique illumination. We used a pair of simple large scale objects with different fine-scale geometric detail. For each object we generated many representations, varying the resources allocated to geometry and texture. The experimental results show that while replacing geometry with texture can be very effective, in some cases the addition of texture does not improve perceived quality, and can sometimes reduce the perceived quality.