## Photon Maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects (1994)

Citations: | 39 - 3 self |

### BibTeX

@MISC{Jensen94photonmaps,

author = {Henrik Wann Jensen and Niels Jørgen Christensen},

title = { Photon Maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects},

year = {1994}

}

### Years of Citing Articles

### OpenURL

### Abstract

This paper describes a bidirectional Monte Carlo ray tracing method simu-lating global illumination in models containing complex objects that do not have to be tessellated. The two pass method combines a first pass light ray tracing (ray casting) with a second pass optimized Monte Carlo ray tracing. In the first pass, the light emitted from the light sources hit objects in the scene and may be reflected or transmitted- a kind of backward path tracing. This step handles all kinds of reflections and not only the specular to diffuse reflections. This turns out to be a valuable optimization. At every object-interaction, energy is stored on the surface of the object. For simple objects an illumination map is used. For complex objects e.g. procedurally based objects like fractals, energy is stored in a photon map. This new concept makes it possible to treat caustics upon such objects without having to parameterize the surface of the objects. The second pass, Monte Carlo ray tracing from the eye, visualizes the scene based upon the result from the rst pass. We use the irradiance gradient method to model diffuse reflections seen directly from the eye. All secondary reflections are taken from the photon maps or the illumination maps. Only the caustic part of the ray casting step is visualized directly.

### Citations

716 | The rendering equation
- KAJIYA
- 1986
(Show Context)
Citation Context ...surfaces and not mirrors. Both methods have been extended into the primary domain of the other. By introducing directional form factors the radiosity methodwas extended to non-di use environment [4]. =-=[5]-=- used Monte Carlo techniques and extended ray tracing into a method called path tracing which intheorysimulates all types of re ections. However, the radiosity extension uses a huge amount of storage ... |

538 |
An image synthesizer
- Perlin
- 1985
(Show Context)
Citation Context ...y 5 10 5 spheres. The rst of the two light sources is an adjustable lamp on the table while the second is xed above the table. The wood and the marble textures have been created using solid texturing =-=[25]-=- and the dices have been created using constructive solid geometry. HERE IS FIGURE 4 HERE IS FIGURE 5 16Photon Maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects HERE IS FIGURE 6 Test s... |

333 | Modelling the interaction of light between diffuse surfaces - Goral, Torrance, et al. - 1984 |

235 | A Ray Tracing Solution for Diffuse Interreflection - Ward, Rubinstein, et al. - 1988 |

154 | A comprehensive physical model for light reflection - HE, TORRANCE, et al. - 1991 |

153 | Adaptive radiosity textures for bidirectional ray tracing - Heckbert - 1990 |

150 |
J.H.: Data structures for range searching
- Bentley, Freidman
- 1979
(Show Context)
Citation Context ...rrgy packed as 4 bytes using Wards real pixels [21], a byte containing the ags and nally two pointers to the remaining data-structure). We store the photons in a multidimensional search tree, kd-tree =-=[22]-=-, and this allows relatively e cient look up and storing of the 11Photon Maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects photons. Alternatives like Voronoi diagrams could have beenus... |

140 | A global illumination solution for general reflectance distributions - Sillion, Arvo, et al. - 1991 |

139 |
A Two-Pass Solution to the Rendering Equation: A Synthesis of Ray Tracing and Radiosity Methods
- Wallace, Cohen, et al.
- 1987
(Show Context)
Citation Context ...the second pass is ray tracing visualizing the radiosity solution and computing specular re ections. Such amethod would only simulate LD*S*E. Thus lacking for instance caustics. To solve this problem =-=[9, 10, 11, 12]-=- uses mirror form factors. However only [12] simulates caustics on non-Lambertian surfaces. Caustics are not simulated well using radiosity, and more advanced hybrid methods use ray tracing from the l... |

125 | A radiosity method for non-diffuse environments - Immel, Cohen, et al. - 1986 |

113 | A Progressive Multi-Pass Method for Global Illumination
- Chen, Rushmeier, et al.
- 1991
(Show Context)
Citation Context ... simulate the caustics visualized directly and then he used radiosity with mirror form factors to simulate indirect illumination. The solution is visualized using distributed ray tracing. Chen et al. =-=[15]-=- re ned Shirleys method by adding path tracing to the visualization stage. Path tracing is used to calculate all re ections seen directly from the eye. All secondary di use re ections are calculated u... |

105 | A general two-pass method integrating specular and diffuse reflection
- Sillion, Puech
- 1989
(Show Context)
Citation Context ...the second pass is ray tracing visualizing the radiosity solution and computing specular re ections. Such amethod would only simulate LD*S*E. Thus lacking for instance caustics. To solve this problem =-=[9, 10, 11, 12]-=- uses mirror form factors. However only [12] simulates caustics on non-Lambertian surfaces. Caustics are not simulated well using radiosity, and more advanced hybrid methods use ray tracing from the l... |

88 |
Particle transport and image synthesis
- ARVO, KIRK
- 1990
(Show Context)
Citation Context ...ed by the ray is deposited into the irradiance map at the given location. Then it is decided whether the ray is absorbed or re ected. The approach used is Russian roulette as described by Arvo et al. =-=[18]-=-. This technique helps us avoid bias and at the same time avoid having to trace a ray through an in nite number of re ections. If the ray is re ected we use the BRDF of the surface to generate a direc... |

54 |
Adaptive Shadow Testing for Ray Tracing
- Ward
- 1991
(Show Context)
Citation Context ...rom the light sources is in principle easily determined. However, it can be very time consuming for scenes with many light sources. [23] have optimized this by using a xed number of shadow rays while =-=[24]-=- uses an adaptive light sampling approach. Both of these methods can be used here. Currently we use simple strati ed sampling of each light source. 14Photon Maps in Bidirectional Monte Carlo Ray Trac... |

46 | The light buffer: A shadow-testing accelerator - Haines, Greenberg - 1986 |

42 |
Real pixels
- Ward
- 1991
(Show Context)
Citation Context ...sable. We can limit the storage requirements by each photon to 28 bytes (12 bytes for the irradiance position, 3 bytes for the normal, 3 oats for the enerrgy packed as 4 bytes using Wards real pixels =-=[21]-=-, a byte containing the ags and nally two pointers to the remaining data-structure). We store the photons in a multidimensional search tree, kd-tree [22], and this allows relatively e cient look up an... |

39 |
B.: Modeling the Interaction of Light Between Di use Surfaces. siggraph
- Goral, Torrance, et al.
- 1984
(Show Context)
Citation Context ...epartment of Graphical Communication Technical University of Denmark Building 116, DK-2800 Lyngby, Denmark 1 Introduction The traditional methods of global illumination: Ray tracing [1] and radiosity =-=[2]-=- do not account for all kinds of indirect illumination in a model. According to the L(SjD)*E classi cation of light paths from the light source, L, to the eye, E, via di use, D, or specular, S, re ect... |

38 | Extending the radiosity method to include specularly reflecting and translucent materials
- Rushmeier, Torrance
- 1990
(Show Context)
Citation Context ...the second pass is ray tracing visualizing the radiosity solution and computing specular re ections. Such amethod would only simulate LD*S*E. Thus lacking for instance caustics. To solve this problem =-=[9, 10, 11, 12]-=- uses mirror form factors. However only [12] simulates caustics on non-Lambertian surfaces. Caustics are not simulated well using radiosity, and more advanced hybrid methods use ray tracing from the l... |

38 |
Backward ray tracing. Developments in Ray Tracing
- Arvo
- 1986
(Show Context)
Citation Context ... caustics on non-Lambertian surfaces. Caustics are not simulated well using radiosity, and more advanced hybrid methods use ray tracing from the light sources (light raytracing) as introduced by Arvo =-=[13]-=- to catch the high irradiance gradients often seen in caustics. Shirley [14] used light raytracing to simulate the caustics visualized directly and then he used radiosity with mirror form factors to s... |

29 |
Computational methods for global illumination and visualisation of complex 3D environments
- Pattanaik
- 1993
(Show Context)
Citation Context ...hotons. With every photon we store the intersection point, the normal, the energy and a bit saying whether this photon is part of a caustic. Such a similar naive approach was rejected by Pattanaik in =-=[20]-=- because of the storage and computational requirements. However, by limiting the photon maps to special objects and using an optimized representation we can make the approach usable. We can limit the ... |

24 | Adaptive Splatting for Specular to Diffuse Light Transport - Collins - 1994 |

22 |
A radiosity method for non-di use environments
- Immel, Cohen, et al.
- 1986
(Show Context)
Citation Context ... use surfaces and not mirrors. Both methods have been extended into the primary domain of the other. By introducing directional form factors the radiosity methodwas extended to non-di use environment =-=[4]-=-. [5] used Monte Carlo techniques and extended ray tracing into a method called path tracing which intheorysimulates all types of re ections. However, the radiosity extension uses a huge amount of sto... |

16 | Measuring and Modeling Anisotropic Re ection - Ward - 1992 |

15 |
A global illumination solution for general re ectance distributions
- Sillion, Arvo, et al.
- 1991
(Show Context)
Citation Context |

11 |
A comprehensive physical model for light re ection
- He, Torrance, et al.
- 1991
(Show Context)
Citation Context ...fore cannot be used in conjunction with illumination maps (texture maps). We would also like the method to be able to deal with arbitrary bidirectional re ectance distribution functions, BRDF's, like =-=[16, 17]-=-. It should however be more e cient than the classic Monte Carlo methods and not su er from noisy results and bias on the solution. 5Photon Maps in Bidirectional Monte Carlo Ray Tracing of Complex Ob... |

7 |
Luminaire Sampling in Distribution Ray Tracing. Global Illumination
- Shirley, Wang
- 1992
(Show Context)
Citation Context ...d in the following sections. 4.0.1 L r�d�l The direct contribution from the light sources is in principle easily determined. However, it can be very time consuming for scenes with many light sources. =-=[23]-=- have optimized this by using a xed number of shadow rays while [24] uses an adaptive light sampling approach. Both of these methods can be used here. Currently we use simple strati ed sampling of eac... |

6 |
Adaptive Splatting for Specular to Di use Light Transport
- Collins
- 1994
(Show Context)
Citation Context ...it energy. Therefore we had to use a rather large number of rays in order to reduce the noise in the image to an acceptable level. A more advanced kernel combined with perhaps wavefront-tracking (See =-=[26]-=-) could very likely help reducing the number of rays in the illumination maps case signi cantly. One of the main purposes of the work was to handle caustics on complex surfaces like fractals. The imag... |

4 |
The Light Bu er: A Shadow-Testing Accelerator
- Haines, Greenberg
- 1986
(Show Context)
Citation Context ... in nite number of re ections. If the ray is re ected we use the BRDF of the surface to generate a direction of the re ected ray. 3.1 Projection maps The projection map is inspired by the light bu er =-=[19]-=-. It is used to localize specular as well as di use surfaces. [14] used feeler rays to solve this problem, however this method might neglect small but important specular objects and edges of mirrors c... |

3 |
A RayTracing Solution for Di use Interre ection
- Ward, Rubinstein, et al.
- 1988
(Show Context)
Citation Context ...thods require a substantial amount of computation time and they have not been of great practical value until now. 3Photon Maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects Ward et al. =-=[6, 7]-=- introduced a caching scheme which signi cantly reduced the computational e ort of path tracing. This technique is however limited to di use surfaces and like path tracing, the method has di culties s... |

2 |
An Improved Illumination Model for Computer Graphics
- Whitted
- 1980
(Show Context)
Citation Context ...rgen Christensen Department of Graphical Communication Technical University of Denmark Building 116, DK-2800 Lyngby, Denmark 1 Introduction The traditional methods of global illumination: Ray tracing =-=[1]-=- and radiosity [2] do not account for all kinds of indirect illumination in a model. According to the L(SjD)*E classi cation of light paths from the light source, L, to the eye, E, via di use, D, or s... |

2 |
The RADIANCE Lighting Simulation System. Global Illumination
- Ward
- 1992
(Show Context)
Citation Context ...ich signi cantly reduced the computational e ort of path tracing. This technique is however limited to di use surfaces and like path tracing, the method has di culties simulating caustics adequately. =-=[8]-=- has solved this problem by using a deterministic calculation of caustics. However, this method is limited to polygon mirrors and it is very expensive in models with more mirrors. The most successful ... |

2 | A Ray Tracing Method for Illumination Calculation - Shirley - 1990 |

1 |
Irradiance Gradients. Global Illumination
- Ward, Heckbert
- 1992
(Show Context)
Citation Context ...thods require a substantial amount of computation time and they have not been of great practical value until now. 3Photon Maps in Bidirectional Monte Carlo Ray Tracing of Complex Objects Ward et al. =-=[6, 7]-=- introduced a caching scheme which signi cantly reduced the computational e ort of path tracing. This technique is however limited to di use surfaces and like path tracing, the method has di culties s... |

1 |
Adaptive RadiosityTextures for Bidirectional RayTracing
- Heckbert
- 1990
(Show Context)
Citation Context ...ot account for all kinds of indirect illumination in a model. According to the L(SjD)*E classi cation of light paths from the light source, L, to the eye, E, via di use, D, or specular, S, re ections =-=[3]-=-, ray tracing only models the LDS*E and LS*E paths. The indirect illumination L(S|D)+DE is only included as a constant ambient term. Radiosity only models LD*E and thus only di use surfaces and not mi... |

1 |
Shirley,ARayTracing Method for Illumination Calculation in Di useSpecular Scenes
- Peter
- 1990
(Show Context)
Citation Context ...radiosity, and more advanced hybrid methods use ray tracing from the light sources (light raytracing) as introduced by Arvo [13] to catch the high irradiance gradients often seen in caustics. Shirley =-=[14]-=- used light raytracing to simulate the caustics visualized directly and then he used radiosity with mirror form factors to simulate indirect illumination. The solution is visualized using distributed ... |