## Estimation of Illuminant Direction and Intensity of Multiple Light Sources (2002)

Venue: | Department of Computer Science, Drexel University. Prior |

Citations: | 20 - 3 self |

### BibTeX

@INPROCEEDINGS{Zhou02estimationof,

author = {Wei Zhou and Chandra Kambhamettu and Ra Kambhamettu},

title = {Estimation of Illuminant Direction and Intensity of Multiple Light Sources},

booktitle = {Department of Computer Science, Drexel University. Prior},

year = {2002},

pages = {206--220}

}

### Years of Citing Articles

### OpenURL

### Abstract

This paper presentsanovel scheme for locating multiple light sources and estimating their intensities from a pair of stereo images of a sphere. No prior knowledge of the location and radius of the sphere is necessary. The sphere surface is not assumed to be a pure Lambertian surface, instead, it has both Lambertian and specular properties.

### Citations

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(Show Context)
Citation Context ...sity estimation. 1 Introduction Light source location information is an important issue for both computer vision and computer graphics applications. For example, shape from shading algorithms [1] [2] =-=[5]-=- need the light source directions as a prior knowledge, segmentation algorithms can be improved if we know the information about the illumination source [15], and we can combine synthetic imagery with... |

86 |
Improved methods of estimating shape from shading using the light source coordinate system
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Citation Context ...ntensity estimation. 1 Introduction Light source location information is an important issue for both computer vision and computer graphics applications. For example, shape from shading algorithms [1] =-=[2]-=- [5] need the light source directions as a prior knowledge, segmentation algorithms can be improved if we know the information about the illumination source [15], and we can combine synthetic imagery ... |

78 |
Finding the illuminant direction
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(Show Context)
Citation Context ...ombine synthetic imagery with a real scene in a seamless manner if the illumination information is available. The works in estimating light source direction can be traced back to the work of Pentland =-=[9]-=- in the early 1980's. Since then, many schemes have been proposed in the context of shape from shading [5] [6] [2] [3] [4], where a point source that is far away is assumed. Multiple light sources det... |

78 |
Computer Graphics
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(Show Context)
Citation Context ...(i1;j1;i2;j2) = D i=1 (i) (i1;j1;i2;j2): (13) From above formula, we know that the intensity di erence D(i1;j1;i2;j2) only depends on the specular intensities. Based on Phong specular-re ection model =-=[12]-=- and using notations shown in gure 2, we have: I (i) specular (i1;j1) =Is (i) (cos 1) ns (14) I (i) specular (i2;j2) =Is (i) (cos 2) ns (15) 1 + 2 (16) where Is (i) is a constant representing the maxi... |

56 |
Linear Shape From Shading
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(Show Context)
Citation Context ...s in estimating light source direction can be traced back to the work of Pentland [9] in the early 1980's. Since then, many schemes have been proposed in the context of shape from shading [5] [6] [2] =-=[3]-=- [4], where a point source that is far away is assumed. Multiple light sources detection is more challenging, and there are relatively few papers dealing with such a problem. In [13], Yang and Yuille ... |

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YUILLE A.: Sources from shading
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(Show Context)
Citation Context ...hading [5] [6] [2] [3] [4], where a point source that is far away is assumed. Multiple light sources detection is more challenging, and there are relatively few papers dealing with such a problem. In =-=[13]-=-, Yang and Yuille show that information on the occluding boundary imposes strong constrains on the light source direction. In [11], Hougen and Ahuja use the least squares technique to solve the multip... |

23 | D.: A simple strategy for calibrating the geometry of light sources
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Citation Context ...mple, shape from shading algorithms [1] [2] [5] need the light source directions as a prior knowledge, segmentation algorithms can be improved if we know the information about the illumination source =-=[15]-=-, and we can combine synthetic imagery with a real scene in a seamless manner if the illumination information is available. The works in estimating light source direction can be traced back to the wor... |

17 |
Illuminant Direction Determination for Multiple Light Sources
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(Show Context)
Citation Context ...ighly ill-posed problem. Recently, many researchers have tried to extract illumination information from a single image together with other information, such as the shape of the object in question. In =-=[7]-=-, Yufei and Yee-Hong use the image of a sphere of known size, where Lambertian surface and directional light sources are assumed. In real world, since the intensities of an object always contains both... |

15 | N.: Estimation of the light source distribution and its use in integrated shape recovery from stereo shading
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(Show Context)
Citation Context ..., and there are relatively few papers dealing with such a problem. In [13], Yang and Yuille show that information on the occluding boundary imposes strong constrains on the light source direction. In =-=[11]-=-, Hougen and Ahuja use the least squares technique to solve the multiple light source problem. But as [13] pointedsII out, without any extra information, estimating light sources from a single image i... |

7 |
D.: Revisiting Pentlandâ€™s estimator of light source direction. Journal of the Optical Society of America A 11
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(Show Context)
Citation Context ...The works in estimating light source direction can be traced back to the work of Pentland [9] in the early 1980's. Since then, many schemes have been proposed in the context of shape from shading [5] =-=[6]-=- [2] [3] [4], where a point source that is far away is assumed. Multiple light sources detection is more challenging, and there are relatively few papers dealing with such a problem. In [13], Yang and... |

4 |
R.: Estimation of illumination, albedo, and shape from shading
- Zheng, Chellappa
- 1991
(Show Context)
Citation Context ...te intensity estimation. 1 Introduction Light source location information is an important issue for both computer vision and computer graphics applications. For example, shape from shading algorithms =-=[1]-=- [2] [5] need the light source directions as a prior knowledge, segmentation algorithms can be improved if we know the information about the illumination source [15], and we can combine synthetic imag... |

4 |
3D shape and light source location from depth and reflectance
- Mancini, Wolff
- 1992
(Show Context)
Citation Context ...i1;j1) in the left image corresponds to pixel (i2;j2) in the right image, from the rst observation we have: Let then Iambient(i1;j1) =Iambient(i2;j2) (9) I (i) diffuse (i1;j1) =I (i) diffuse (i2;j2): =-=(10)-=- The intensity di erence between these two pixels is: D(i1;j1;i2;j2) =I(i1;j1) , I(i2;j2) nX nX = Iambient(i1;j1)+ (I i=1 (i) (i) diffuse (i1;j1)+I specular (i1;j1)) , Iambient(i2;j2) , nX i=1 (I (i) ... |

4 |
Calibration of Light Sources
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(Show Context)
Citation Context ...lways contains both specular and di use intensities and the size of the object is always unknown, the assumption of pure Lambertian surface and known size of the sphere restricts its applications. In =-=[14]-=- [15], two or three spheres are used, and the specular properties of a shining surface is used to triangulate the locations of light sources. Since it only uses the specular information, the intensiti... |

1 |
Determining re ectance parameters using range and brightness images
- Ikeuchi, Sato
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(Show Context)
Citation Context ... estimating light source direction can be traced back to the work of Pentland [9] in the early 1980's. Since then, many schemes have been proposed in the context of shape from shading [5] [6] [2] [3] =-=[4]-=-, where a point source that is far away is assumed. Multiple light sources detection is more challenging, and there are relatively few papers dealing with such a problem. In [13], Yang and Yuille show... |