| OCR Text |
Show 15 A collection of such objects comprises a visual database. An image synthesis program creates a computer image from a databas . Ray tracing is one such technique and scan conversion is another. A lighting model is incorporated into the computer image by various models for shading. lmag discrepancies caused by undersampling are called aliasing problems; techniques to avoid such artifacts are called antialiasing. Techniques for adding detailed surface features to objects during rendering are called texture rnapping. Two forms of texture mapping are currently popular: color variation and normal perturbation texture mapping. A new method of texture mapping proposed by this thesis is called surface perturbation or displacement mapping. 2.3 Texture Mapping Objects in the real world often have complex macroscopic structures on their surfaces. The aggregate of these macroscopic features, including such features as bumps, folds, and wrinkles are called texture. Putting texture on objects is important in computer graphics because texture provides the visual cues that allow easy identification of objects, an important goal. Unfortunately, the complexity of these features is difficult and costly to model on a computer. As a result, texture is usually modeled separately from objects, then applied during the rendering process to achieve visual realism. |
