# Rendering antialiased shadows with depth maps

@inproceedings{Reeves1987RenderingAS, title={Rendering antialiased shadows with depth maps}, author={William T. Reeves and D. Salesin and Robert L. Cook}, booktitle={SIGGRAPH '87}, year={1987} }

We present a solution to the aliasing problem for shadow algorithms that use depth maps. The solution is based on a new filtering technique called percentage closer filtering. In addition to antialiasing, the improved algorithm provides soft shadow boundaries that resemble penumbrae. We describe the new algorithm in detail, demonstrate the effects of its parameters, and analyze its performance.

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#### References

SHOWING 1-10 OF 37 REFERENCES

Generating soft shadows with a depth buffer algorithm

- Computer Science
- IEEE Computer Graphics and Applications
- 1984

An algorithm is developed that combines an existing shadowing method with a popular visible surface rendering technique, called a depth buffer, to generate soft shadows resulting from light sources of finite extent. Expand

Algorithms for antialiased cast shadows

- Computer Science
- Comput. Graph.
- 1985

The purpose of this study is to explore in depth the most common problem present in images, the aliasing, or more generally speaking, the sampling problem, and imply a specific approach in the hidden surface determination, the introduction of a variation of the already used A-buffer or Z-buffers, as well as an extensive study of the filtering problem. Expand

Atmospheric illumination and shadows

- Physics, Computer Science
- SIGGRAPH
- 1986

The shadow volume algorithm of Frank Crow was reorganized to provide information on the regions of illuminated space in front of each visible surface, so when the atmosphere is partly in shadow, columns of scattered light will be visible. Expand

Shadow algorithms for computer graphics

- Computer Science
- SIGGRAPH '77
- 1977

A classification of shadow algorithms delineates three approaches: shadow computation during scanout; division of object surfaces into shadowed and unshadowed areas prior to removal of hidden surfaces; and inclusion of shadow volumes in the object data. Expand

Ray tracing with cones

- Computer Science
- SIGGRAPH '84
- 1984

A new approach to ray tracing is introduced, which tries to model light propagation with more fidelity and includes a better method of anti-aliasing, a way of calculating fuzzy shadows and dull reflections, and a method of calculating the correct level of detail in a procedural model and texture map. Expand

An improved illumination model for shaded display

- Computer Science
- CACM
- 1980

Consideration of all of these factors allows the shader to accurately simulate true reflection, shadows, and refraction, as well as the effects simulated by conventional shaders. Expand

Casting curved shadows on curved surfaces

- Computer Science
- SIGGRAPH '78
- 1978

A simple algorithm is described which utilizes Z-buffer visible surface computation to display shadows cast by objects modelled of smooth surface patches, and is contrasted with a less costly method for casting the shadows of the environment on a single ground plane. Expand

Beam tracing polygonal objects

- Computer Science, Mathematics
- SIGGRAPH
- 1984

An algorithm that utilizes the spatial coherence of polygonal environments by combining features of both image and object space hidden surface algorithms is described, which enables very fast scan conversion and high resolution output. Expand

Stochastic sampling in computer graphics

- Computer Science
- TOGS
- 1986

It is shown that aliasing artifacts are not an inherent part of point sampling, but a consequence of using regularly spaced samples, and frequencies above the Nyquist limit do not alias, but instead appear as noise of the correct average intensity. Expand

Polygon shadow generation

- Mathematics, Computer Science
- SIGGRAPH '78
- 1978

A general purpose method for generating shadows using a polygonal coordinate data base based on an object space polygon clipping hidden surface removal algorithm, which may be easily created and viewed from any observer position with no additional depth sorting time required. Expand