Real-time per-pixel rendering of textiles for virtual textile catalogues

Abstract We present recent results from an EPSRC funded project VirTex (Virtual Textile Catalogues). The goal of this project is to develop graphics and image-processing software for the capture, storage, search, retrieval and visualisation of 3D textile samples. The ultimate objective is to develop a webbased application that allows the user to search a database for suitable textiles and to visualize selected samples using real-time photorealistic 3D animation. The main novelty of this work is in the combined use of photometric stereo and real-time per-pixelrendering for the capture and visualisation of textile samples. Photometric stereo is a simple method that allows both the bump map and the colour map of a surface texture to be captured digitally. It uses a single fixed camera to obtain three images under three different illumination conditions. The colour map is the image that would be obtained under diffuse lighting. The bump map describes the small undulations of the surface relief. When imported into a standard graphics program these images can be used to texture 3D models. The appearance is particularly photorealistic, especially under changing illumination and viewpoints. The viewer can manipulate both viewpoint and lighting to gain a deeper perception of the properties of the textile sample. In addition, these images can be used with 3D models of products to provide extremely accurate visualisations for the customer. Until recently these images could only be rendered using ray-tracing software. However, recent consumer-level graphics cards from companies such as Nvidia, ATI and 3Dlabs now provide real-time per-pixel shading. We have developed software that takes advantage of the advanced rendering features of these cards to render images in real-time. It uses photometrically acquired bump and colour maps of textiles to provide real-time visualisation of a textile sample, under user-controlled illumination, pose and flex.