An algorithm for generating shadows with an umbra and penumbra due to distributed light sources is presented. The method used is based on the inclusion of the shadow volumes in the object data processed by a depth-buffer visible surface computation. The standard depth-buffer data structure is modified to allow the handling of shadows with a depth-buffer hidden surface algorithm. The algorithm i...

Rendering shadows quickly is an active area of computer graphics research. This dissertation improves the practicality of using a small number of point-sampled light sources to approximate soft shadows. Results are presented from two perceptual experiments demonstrating the perceptual efficacy of soft shadows as spatial cues for a specific set of tasks . A third experiment found coarse point-sa...

We report the growth and characterization of patterned ZnCdSe/ZnCdMgSe quantum-well ~QW! structures grown adjacent to each other on a single InP substrate. Each structure emits at a different wavelength range spanning the visible range. Stripe and square-shaped QW structures of different emission wavelengths, with lateral dimensions between 15 and 60 mm, were deposited sequentially by shadow ma...

There is often interest in identifying geometry in a scene. Edge detection is an established method of looking at scene geometry, but naive edge detection in a complex scene discerns little about the physical geometry; light and shadowing effects especially in outdoor scenes can cause edge detectors to mistakenly classify texture and shadow edges as geometry edges. However, with a sample of sev...

Bidirectional path tracing is a fairly new Monte Carlo algorithm for physically based rendering. Introduced as a generalisation of path tracing, the algorithm traces paths for each pixel, not only from the eye point but also from the light sources. It subsequently links the intersection points on the respective paths by means of shadow rays. Each shadow ray determines if a lighting contribution...

We present a method for rendering aesthetically correct soft shadows that exhibit smooth inner and outer penumbrae and self-shadowing. Our approach is an extension of ordinary shadow mapping; in an additional step, occluder shadow silhouette edges, as seen from the center of an area light, are detected and extruded into so-called Skirts. This step is done entirely in image space, and as such do...

We present a new method for interactive illumination computations based on precomputed visibility using coherent shadow maps (CSMs). It is well-known that visibility queries dominate the cost of physically based rendering. Precomputing all visibility events, for instance in the form of many shadow maps, enables fast queries and allows for real-time computation of illumination but requires prohi...