## Rendering Caustics on Non-Lambertian Surfaces (1996)

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Venue: | Computer Graphics Forum |

Citations: | 36 - 3 self |

### BibTeX

@ARTICLE{Jensen96renderingcaustics,

author = {Henrik Wann Jensen},

title = {Rendering Caustics on Non-Lambertian Surfaces},

journal = {Computer Graphics Forum},

year = {1996},

volume = {16},

pages = {116--121}

}

### Years of Citing Articles

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### Abstract

This paper presents a new technique for rendering caustics on non-Lambertian surfaces. The method is based on an extension of the photon map which removes previous restrictions limiting the usage to Lambertian surfaces. We add information about the incoming direction to the photons and this allows us to combine the photon map with arbitrary reflectance functions. Furthermore we introduce balancing of the photon map which not only reduces the memory requirements but also significantly reduces the rendering time. We have used the method to render caustics on surfaces with reflectance functions varying from Lambertian to glossy specular. Keywords: Caustics, Photon Map, Ray Tracing, Rendering. 1 Introduction Caustics provides some of the most spectacular patterns of light in nature. Caustics are formed when light reflected from or transmitted through a specular surfaces strikes a diffuse surface. An example is the caustic formed as light shines through a glass of wine onto a table. In ...

### Citations

1117 |
Multidimensional binary search trees used for associative senrching
- BENTLEY
- 1975
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Citation Context ...In this way we obtain an unbiased solution without 3shave to trace each photon through an infinite number of specular reflections. Every photon is stored within the photon map.As [9] we use a kd-tree =-=[2]-=- to store the photons.While rendering the scene we need a data-structure that allows us to quickly locate photons within a given volume.Furthermore we need a very compact data-structure since we want ... |

713 | The rendering equation
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- 1986
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Citation Context ...cing [22] diffuse surfaces are only illuminated by the light sources. Caustics which are indirect illumination on the diffuse surfaces are not rendered at all. Even the stochastic ray tracing methods =-=[5, 8]-=- cannot render caustics properly. In order to integrate the computation of caustics into ray tracing it is necessary to compute illumination from light transmitted via specular surfaces. This computat... |

368 |
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Citation Context ...cing [22] diffuse surfaces are only illuminated by the light sources. Caustics which are indirect illumination on the diffuse surfaces are not rendered at all. Even the stochastic ray tracing methods =-=[5, 8]-=- cannot render caustics properly. In order to integrate the computation of caustics into ray tracing it is necessary to compute illumination from light transmitted via specular surfaces. This computat... |

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- 1990
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Citation Context ... are created as textures on the Lambertian surfaces within the scene. A problem with this approach is the fact that a large number of photons must be used to eliminate noise in the caustics. Heckbert =-=[7]-=- introduced a method that adaptively subdivided the illumination map into area elements (rexes) with a size corresponding to the local density of the photon-hits. Chen et al. [3] and Collins [4] use a... |

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- 1993
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Citation Context ...mbertian surfaces. With backwards beam tracing the illumination map can be replaced by caustic polygons that represent illumination from caustics on Lambertian surfaces. In bidirectional path tracing =-=[11, 18]-=- the rendering of caustics is significantly improved compared to traditional path tracing [8]. The method is however still purely stochastic and it still requires a large amount of sample rays to prod... |

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Citation Context ...he caustics. Heckbert [7] introduced a method that adaptively subdivided the illumination map into area elements (rexes) with a size corresponding to the local density of the photon-hits. Chen et al. =-=[3]-=- and Collins [4] use a fixed illumination map. To eliminate noise they use different filter-kernels to spread the energy from each photon onto several area-elements. Jensen et al. [9] stored all photo... |

65 | A ray tracing method for illumination calculation in diffuse specular scenes
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- 1990
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Citation Context ... are clearly the backward ray tracing techniques as introduced by Arvo. These methods are often faster and more general than other approaches and they are often used in global illumination techniques =-=[3, 9, 16]-=- to render caustics. They do unfortunately have one significant drawback - they are limited to Lambertian surfaces. In many situations this is not a problem. However, within global illumination where ... |

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- 1992
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Citation Context ...om light transmitted via specular surfaces. This computation is in most situations very complex and it has been solved only for a simple class of specular objects (ie. polygons [20]). Mitchell et al. =-=[12]-=- has presented a very comprehensive technique and their method is capable of handling caustics from implicit surfaces. The method is unfortunately very complex and also very time consuming. Arvo [1] e... |

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- 1993
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Citation Context ...tely simulating the physical behavior of different materials. However we are only interested in a simple model that can be used to validate our algorithm. A suitable model was presented by Schlick in =-=[13]-=-. This model is simple and it has the very nice property that it provides a continuous transition from Lambertian reflection to glossy specular reflection. We omit the usage of anisotropic reflection ... |

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Light-water interaction using backward beam tracing
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- 1990
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Citation Context ...owever require large amounts of memory in complex scenes. In scenes with simple objects it is possible to avoid the photon based approach.If the specular objects are polyhedral backwards beam tracing =-=[14, 15, 21]-=- can be used to render caustics on the Lambertian surfaces.With backwards beam tracing the illumination map can be replaced by caustic polygons that represent illumination from caustics on Lambertian ... |

42 |
Real pixels
- Ward
- 1991
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Citation Context ...wo child pointers which would otherwise increase the memory requirements for each photon with 8 bytes (40%). The energy is represented as 3 floats packed into 4 bytes using the technique described in =-=[19]-=-. 3 Rendering Caustics with the Photon Map In standard ray tracing diffuse surfaces are only illuminated by the light sources. By introducing the photon map we have photons representing energy from ca... |

38 |
Backward ray tracing. Developments in Ray Tracing
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- 1986
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Citation Context ...l.[12] has presented a very comprehensive technique and their method is capable of handling caustics from implicit surfaces.The method is unfortunately very complex and also very time consuming. Arvo =-=[1]-=- extended the standard ray tracing algorithm by introducing a preprocessing step in which caustics are computed.This preprocessing step uses backward ray tracing (also known as light ray tracing, illu... |

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24 | Adaptive Splatting for Specular to Diffuse Light Transport
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Citation Context ...kbert [7] introduced a method that adaptively subdivided the illumination map into area elements (rexes) with a size corresponding to the local density of the photon-hits. Chen et al. [3] and Collins =-=[4]-=- use a fixed illumination map. To eliminate noise they use different filter-kernels to spread the energy from each photon onto several area-elements. Jensen et al. [9] stored all photon-hits explicitl... |

9 |
The RADIANCE Lighting Simulation System
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Citation Context ...compute illumination from light transmitted via specular surfaces. This computation is in most situations very complex and it has been solved only for a simple class of specular objects (ie. polygons =-=[20]-=-). Mitchell et al. [12] has presented a very comprehensive technique and their method is capable of handling caustics from implicit surfaces. The method is unfortunately very complex and also very tim... |

6 | Adaptive Splatting for Specular to Di use Light Transport - Collins - 1994 |

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Backward Ray Tracing". Developments in Ray Tracing
- Arvo
- 1986
(Show Context)
Citation Context ... [12] has presented a very comprehensive technique and their method is capable of handling caustics from implicit surfaces. The method is unfortunately very complex and also very time consuming. Arvo =-=[1]-=- extended the standard ray tracing algorithm by introducing a preprocessing step in which caustics are computed. This preprocessing step uses backward ray tracing (also known as light ray tracing, ill... |

3 |
and Niels Jrgen Christensen: "Photon maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects
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- 1995
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Citation Context ...its. Chen et al. [3] and Collins [4] use a fixed illumination map. To eliminate noise they use different filter-kernels to spread the energy from each photon onto several area-elements. Jensen et al. =-=[9]-=- stored all photon-hits explicitly in a photon map and avoided using the illumination map. Instead they introduced a new technique for estimating the number of photons per area by looking only on the ... |

3 |
and Niels Jørgen Christensen: ”Photon maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects
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(Show Context)
Citation Context ...ton-hits.Chen et al.[3] and Collins [4] use a fixed illumination map.To eliminate noise they use different filter-kernels to spread the energy from each photon onto several area-elements.Jensen et al.=-=[9]-=- stored all photon-hits explicitly in a photon map and avoided using the illumination map.Instead they introduced a new technique for estimating the number of photons per area by looking only on the d... |

3 | A customizable re ectance model for everyday rendering - Schlick - 1993 |

2 |
Louis: "Multidimensional Binary Search Trees Used for Associative Searching
- Bentley
- 1975
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Citation Context ... In this way we obtain an unbiased solution without have to trace each photon through an infinite number of specular reflections. Every photon is stored within the photon map. As [9] we use a kd-tree =-=[2]-=- to store the photons. While rendering the scene we need a data-structure that allows us to quickly locate photons within a given volume. Furthermore we need a very compact datastructure since we want... |

2 | Wann: "Importance Driven Path Tracing using the Photon Map - Jensen - 1995 |

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2 |
Eric and Leonidas Guibas: "Bidirectional Estimators for Light Transport
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Citation Context ...mbertian surfaces. With backwards beam tracing the illumination map can be replaced by caustic polygons that represent illumination from caustics on Lambertian surfaces. In bidirectional path tracing =-=[11, 18]-=- the rendering of caustics is significantly improved compared to traditional path tracing [8]. The method is however still purely stochastic and it still requires a large amount of sample rays to prod... |

2 |
An Improved Illumination Model for Computer Graphics
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- 1980
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Citation Context ...t reflected from or transmitted through a specular surfaces strikes a diffuse surface.An example is the caustic formed as light shines through a glass of wine onto a table. In traditional ray tracing =-=[22]-=- diffuse surfaces are only illuminated by the light sources.Caustics which are indirect illumination on the diffuse surfaces are not rendered at all.Even the stochastic ray tracing methods [5, 8] cann... |

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1 |
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Citation Context ...wever require large amounts of memory in complex scenes. In scenes with simple objects it is possible to avoid the photon based approach. If the specular objects are polyhedral backwards beam tracing =-=[14, 15, 21]-=- can be used to render caustics on the Lambertian surfaces. With backwards beam tracing the illumination map can be replaced by caustic polygons that represent illumination from caustics on Lambertian... |

1 |
Takafumi Saito and Tokiichiro Takahashi: "Rendering Techniques for Transparent Objects
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- 1989
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Citation Context ...wever require large amounts of memory in complex scenes. In scenes with simple objects it is possible to avoid the photon based approach. If the specular objects are polyhedral backwards beam tracing =-=[14, 15, 21]-=- can be used to render caustics on the Lambertian surfaces. With backwards beam tracing the illumination map can be replaced by caustic polygons that represent illumination from caustics on Lambertian... |

1 |
Eric and Leonidas Guibas: ”Bidirectional Estimators for Light Transport
- Veach
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Citation Context ...bertian surfaces.With backwards beam tracing the illumination map can be replaced by caustic polygons that represent illumination from caustics on Lambertian surfaces. 2sIn bidirectional path tracing =-=[11, 18]-=- the rendering of caustics is significantly improved compared to traditional path tracing [8].The method is however still purely stochastic and it still requires a large amount of sample rays to produ... |

1 | rgen Christensen: "Photon maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects - Jensen, Niels - 1995 |