This paper, authored by James F. Blinn and Martin E. Newell from the University of Utah, discusses extensions to Catmull's 1974 algorithm for rendering continuous-tone images of bivariate surface patches. The extensions focus on texture simulation and lighting models, leveraging digital signal processing theory and curved surface mathematics to enhance image quality. **Texture Mapping:** - Catmull's algorithm subdivide patches into smaller fragments until each fragment covers only one picture element. - Texture mapping uses the parametric values of the patch within each picture element to map patterns onto the surface. - Aliasing issues are addressed by filtering high spatial frequency components, implemented through a weighted average of surrounding pattern values. - Various texture patterns, including simple grids, hand-drawn images, photographs, and Fourier synthesis, are demonstrated. **Reflection in Curved Surfaces:** - The algorithm provides accurate surface normals at every picture element, enabling realistic reflection simulations. - Reflection directions are determined using the surface normal and viewing position. - The environment is modeled as a two-dimensional projection, and reflected light intensity is read from an environment map. - Combining texture mapping and reflection techniques produces images with patterned shiny surfaces. **Resource Requirements:** - Images were generated on a PDP-11/45 computer with a 256K-byte frame buffer. - Non-textured objects took about 25 minutes to render, with texture or reflection increasing the time by about 10%. **Conclusions:** - The refined and extended Catmull's algorithm significantly improves the naturalness of generated images, enhancing pattern and texture generation and reflection simulation. The paper also includes several figures illustrating the techniques and their applications.This paper, authored by James F. Blinn and Martin E. Newell from the University of Utah, discusses extensions to Catmull's 1974 algorithm for rendering continuous-tone images of bivariate surface patches. The extensions focus on texture simulation and lighting models, leveraging digital signal processing theory and curved surface mathematics to enhance image quality. **Texture Mapping:** - Catmull's algorithm subdivide patches into smaller fragments until each fragment covers only one picture element. - Texture mapping uses the parametric values of the patch within each picture element to map patterns onto the surface. - Aliasing issues are addressed by filtering high spatial frequency components, implemented through a weighted average of surrounding pattern values. - Various texture patterns, including simple grids, hand-drawn images, photographs, and Fourier synthesis, are demonstrated. **Reflection in Curved Surfaces:** - The algorithm provides accurate surface normals at every picture element, enabling realistic reflection simulations. - Reflection directions are determined using the surface normal and viewing position. - The environment is modeled as a two-dimensional projection, and reflected light intensity is read from an environment map. - Combining texture mapping and reflection techniques produces images with patterned shiny surfaces. **Resource Requirements:** - Images were generated on a PDP-11/45 computer with a 256K-byte frame buffer. - Non-textured objects took about 25 minutes to render, with texture or reflection increasing the time by about 10%. **Conclusions:** - The refined and extended Catmull's algorithm significantly improves the naturalness of generated images, enhancing pattern and texture generation and reflection simulation. The paper also includes several figures illustrating the techniques and their applications.