Micro-appearance models explicitly model the interaction of light with microgeometry at the fiber scale to produce realistic appearance. To effectively match them to real fabrics, we introduce a new appearance matching framework to determine their parameters. Given a micro-appearance model and photographs of the fabric under many different lighting conditions, we optimize for parameters that best match the photographs using a method based on calculating derivatives during rendering. This highly applicable framework, we believe, is a useful research tool because it simplifies development and testing of new models. Using the framework, we systematically compare several types of micro-appearance models. We acquired computed microtomography (micro CT) scans of several fabrics, photographed the fabrics under many viewing/illumination conditions, and matched several appearance models to this data. We compare a new fiber-based light scattering model to the previously used microflake model. We also compare representing cloth microgeometry using volumes derived directly from the micro CT data to using explicit fibers reconstructed from the volumes. From our comparisons, we make the following conclusions: (1) given a fiber-based scattering model, volume- and fiber-based microgeometry representations are capable of very similar quality, and (2) using a fiber-specific scattering model is crucial to good results as it achieves considerably higher accuracy than prior work.

Abstract This practice and experience paper describes a robust C++ implementation of several non‐linear solid three‐dimensional deformable object strategies commonly employed in computer graphics, named the Vega finite element method (FEM) simulation library. Deformable models supported include co‐rotational linear FEM elasticity, Saint–Venant Kirchhoff FEM model, mass–spring system and invertible FEM models: neo‐Hookean, Saint–Venant Kirchhoff and Mooney–Rivlin. We provide several timestepping schemes, including implicit Newmark and backward Euler integrators, and explicit central differences. The implementation of material models is separated from integration, which makes it possible to employ our code not only for simulation, but also for deformable object control and shape modelling. We extensively compare the different material models and timestepping schemes. We provide practical experience and insight gained while using our code in several computer animation and simulation research projects.

Although laboratory user studies are the most common method for validating the utility of information visualization systems, it may be difficult to determine if such studies accurately reflect the tasks of real users. In this paper, we describe a longitudinal real-world user evaluation of a visual and interactive Web search interface designed to support exploratory searching: the HotMap.com. Although we experienced some attrition during the course of the four-week study, the results indicate that many of the features of the system are beneficial and useful in real-world use. Although exploratory search comprised a small portion of the total search activities undertaken, the features of the HotMap.com which support query refinement and search results exploration did not interfere with the more common targeted searching tasks. As a result, most participants indicated that they found the system useful and easy to use.

TheHotMap.com is an example of a next-generation Web search interface, wherein users are able to take an active role in the Web search process. Information that can assist searchers in their Web search tasks is presented in a visual manner. The system supports user interaction both during the query refinement process, as well as the search results exploration process. This paper describes the features of TheHotMap.com; usage log analysis illustrates the benefits of supporting flexible interaction within a single unified Web search interface.