Search For:

Displaying 1-29 out of 29 total
A coaxial optical scanner for synchronous acquisition of 3D geometry and surface reflectance
Found in: ACM Transactions on Graphics (TOG)
By Jason Lawrence, Michael Holroyd, Todd Zickler, Jason Lawrence, Michael Holroyd, Todd Zickler, Jason Lawrence, Michael Holroyd, Todd Zickler, Jason Lawrence, Michael Holroyd, Todd Zickler
Issue Date:July 2010
pp. 1-10
We present a novel optical setup and processing pipeline for measuring the 3D geometry and spatially-varying surface reflectance of physical objects. Central to our design is a digital camera and a high frequency spatially-modulated light source aligned to...
     
Modeling Radiometric Uncertainty for Vision with Tone-Mapped Color Images
Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence
By Ayan Chakrabarti,Ying Xiong,Baochen Sun,Trevor Darrell,Daniel Scharstein,Todd Zickler,Kate Saenko
Issue Date:November 2014
pp. 1-1
To produce images that are suitable for display, tone-mapping is widely used in digital cameras to map linear color measurements into narrow gamuts with limited dynamic range. This introduces non-linear distortion that must be undone, through a radiometric...
 
The Geometry of Reflectance Symmetries
Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence
By Ping Tan,Long Quan,Todd Zickler
Issue Date:December 2011
pp. 2506-2520
Different materials reflect light in different ways, and this reflectance interacts with shape, lighting, and viewpoint to determine an object's image. Common materials exhibit diverse reflectance effects, and this is a significant source of difficulty for...
 
Shape from Specular Flow
Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence
By Yair Adato, Yuriy Vasilyev, Todd Zickler, Ohad Ben-Shahar
Issue Date:November 2010
pp. 2054-2070
An image of a specular (mirror-like) object is nothing but a distorted reflection of its environment. When the environment is unknown, reconstructing shape from such an image can be very difficult. This reconstruction task can be made tractable when, inste...
 
Toward Wide-Angle Microvision Sensors
Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence
By Sanjeev J. Koppal,Ioannis Gkioulekas,Travis Young, Hyunsung Park,Kenneth B. Crozier,Geoffrey L. Barrows,Todd Zickler
Issue Date:December 2013
pp. 2982-2996
Achieving computer vision on microscale devices is a challenge. On these platforms, the power and mass constraints are severe enough for even the most common computations (matrix manipulations, convolution, etc.) to be difficult. This paper proposes and an...
 
Analyzing spatially-varying blur
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Ayan Chakrabarti, Todd Zickler, William T. Freeman
Issue Date:June 2010
pp. 2512-2519
Blur is caused by a pixel receiving light from multiple scene points, and in many cases, such as object motion, the induced blur varies spatially across the image plane. However, the seemingly straight-forward task of estimating spatially-varying blur from...
 
Autotagging Facebook: Social network context improves photo annotation
Found in: Computer Vision and Pattern Recognition Workshop
By Zak Stone, Todd Zickler, Trevor Darrell
Issue Date:June 2008
pp. 1-8
Most personal photos that are shared online are embedded in some form of social network, and these social networks are a potent source of contextual information that can be leveraged for automatic image understanding. In this paper, we investigate the util...
 
Color constancy beyond bags of pixels
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Ayan Chakrabarti, Keigo Hirakawa, Todd Zickler
Issue Date:June 2008
pp. 1-6
Estimating the color of a scene illuminant often plays a central role in computational color constancy. While this problem has received significant attention, the methods that exist do not maximally leverage spatial dependencies between pixels. Indeed, mos...
 
Dense specular shape from multiple specular flows
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Yuriy Vasilyev, Yair Adato, Todd Zickler, Ohad Ben-Shahar
Issue Date:June 2008
pp. 1-8
The inference of specular (mirror-like) shape is a particularly difficult problem because an image of a specular object is nothing but a distortion of the surrounding environment. Consequently, when the environment is unknown, such an image would seem to c...
 
Photometric stereo with non-parametric and spatially-varying reflectance
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Neil Alldrin, Todd Zickler, David Kriegman
Issue Date:June 2008
pp. 1-8
We present a method for simultaneously recovering shape and spatially varying reflectance of a surface from photometric stereo images. The distinguishing feature of our approach is its generality; it does not rely on a specific parametric reflectance model...
 
What do color changes reveal about an outdoor scene?
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Kalyan Sunkavalli, Fabiano Romeiro, Wojciech Matusik, Todd Zickler, Hanspeter Pfister
Issue Date:June 2008
pp. 1-8
In an extended image sequence of an outdoor scene, one observes changes in color induced by variations in the spectral composition of daylight. This paper proposes a model for these temporal color changes and explores its use for the analysis of outdoor sc...
 
The von Kries Hypothesis and a Basis for Color Constancy
Found in: Computer Vision, IEEE International Conference on
By Hamilton Y. Chong, Steven J. Gortler, Todd Zickler
Issue Date:October 2007
pp. 1-8
Color constancy is almost exclusively modeled with diagonal transforms. However, the choice of basis under which diagonal transforms are taken is traditionally and hoc. Attempts to remedy the situation have been hindered by the fact that no joint character...
 
Toward a Theory of Shape from Specular Flow
Found in: Computer Vision, IEEE International Conference on
By Yair Adato, Yuriy Vasilyev, Ohad Ben-Shahar, Todd Zickler
Issue Date:October 2007
pp. 1-8
The image of a curved, specular (mirror-like) surface is a distorted reflection of the environment. The goal of our work is to develop a framework for recovering general shape from such distortions when the environment is neither calibrated nor known. To a...
 
Reciprocal Image Features for Uncalibrated Helmholtz Stereopsis
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Todd Zickler
Issue Date:June 2006
pp. 1801-1808
Helmholtz stereopsis is a surface reconstruction method that exploits reciprocity for the recovery of 3D shape without an assumed BRDF model, and it has been shown to yield high quality results when the cameras and light sources are carefully calibrated. I...
 
Color Subspaces as Photometric Invariants
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Todd Zickler, Satya P. Mallick, David J. Kriegman, Peter N. Belhumeur
Issue Date:June 2006
pp. 2000-2010
Complex reflectance phenomena such as specular reflections confound many vision problems since they produce image ?features? that do not correspond directly to intrinsic surface properties such as shape and spectral reflectance. A common approach to mitiga...
 
From Shading to Local Shape
Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence
By Ying Xiong,Ayan Chakrabarti,Ronen Basri,Steven J. Gortler,David W. Jacobs,Todd Zickler
Issue Date:August 2014
pp. 1
We develop a framework for extracting a concise representation of the shape information available from diffuse shading in a small image patch. This produces a mid-level scene descriptor, comprised of local shape distributions that are inferred separately a...
 
Rethinking color cameras
Found in: 2014 IEEE International Conference on Computational Photography (ICCP)
By Ayan Chakrabarti,William T. Freeman,Todd Zickler
Issue Date:May 2014
pp. 1-8
Digital color cameras make sub-sampled measurements of color at alternating pixel locations, and then “demosaick” these measurements to create full color images by up-sampling. This allows traditional cameras with restricted processing hardware to produce ...
   
Finding Group Interactions in Social Clutter
Found in: 2013 IEEE Conference on Computer Vision and Pattern Recognition (CVPR)
By Ruonan Li,Parker Porfilio,Todd Zickler
Issue Date:June 2013
pp. 2722-2729
We consider the problem of finding distinctive social interactions involving groups of agents embedded in larger social gatherings. Given a pre-defined gallery of short exemplar interaction videos, and a long input video of a large gathering (with approxim...
 
Isotropy, Reciprocity and the Generalized Bas-Relief Ambiguity
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Ping Tan, Satya P. Mallick, Long Quan, David J. Kriegman, Todd Zickler
Issue Date:June 2007
pp. 1-8
A set of images of a Lambertian surface under varying lighting directions defines its shape up to a three-parameter Generalized Bas-Relief (GBR) ambiguity. In this paper, we examine this ambiguity in the context of surfaces having an additive non-Lambertia...
 
Beyond Lambert: Reconstructing Surfaces with Arbitrary BRDFs
Found in: Computer Vision, IEEE International Conference on
By Sebastian Magda, David J. Kriegman, Todd Zickler, Peter N. Belhumeur
Issue Date:July 2001
pp. 391
We address an open and hitherto neglected problem in computer vision, how to reconstruct the geometry of objects with arbitrary and possibly anisotropic bidirectional reflectance distribution functions (BRDFs). Present reconstruction techniques, whether st...
 
Inverse volume rendering with material dictionaries
Found in: ACM Transactions on Graphics (TOG)
By Anat Levin, Ioannis Gkioulekas, Shuang Zhao, Todd Zickler, Kavita Bala
Issue Date:November 2013
pp. 1-13
Translucent materials are ubiquitous, and simulating their appearance requires accurate physical parameters. However, physically-accurate parameters for scattering materials are difficult to acquire. We introduce an optimization framework for measuring bul...
     
Understanding the role of phase function in translucent appearance
Found in: ACM Transactions on Graphics (TOG)
By Bei Xiao, Edward H. Adelson, Ioannis Gkioulekas, Kavita Bala, Shuang Zhao, Todd Zickler
Issue Date:September 2013
pp. 1-19
Multiple scattering contributes critically to the characteristic translucent appearance of food, liquids, skin, and crystals; but little is known about how it is perceived by human observers. This article explores the perception of translucency by studying...
     
Fabricating BRDFs at high spatial resolution using wave optics
Found in: ACM Transactions on Graphics (TOG)
By Anat Levin, Daniel Glasner, Frédo Durand, Todd Zickler, William Freeman, Wojciech Matusik, Ying Xiong
Issue Date:July 2013
pp. 1-14
Recent attempts to fabricate surfaces with custom reflectance functions boast impressive angular resolution, yet their spatial resolution is limited. In this paper we present a method to construct spatially varying reflectance at a high resolution of up to...
     
A coaxial optical scanner for synchronous acquisition of 3D geometry and surface reflectance
Found in: ACM SIGGRAPH 2010 papers (SIGGRAPH '10)
By Jason Lawrence, Michael Holroyd, Todd Zickler
Issue Date:July 2010
pp. 10-18
We present a novel optical setup and processing pipeline for measuring the 3D geometry and spatially-varying surface reflectance of physical objects. Central to our design is a digital camera and a high frequency spatially-modulated light source aligned to...
     
A photometric approach for estimating normals and tangents
Found in: ACM Transactions on Graphics (TOG)
By Greg Humphreys, Jason Lawrence, Michael Holroyd, Todd Zickler
Issue Date:December 2008
pp. 1-49
This paper presents a technique for acquiring the shape of real-world objects with complex isotropic and anisotropic reflectance. Our method estimates the local normal and tangent vectors at each pixel in a reference view from a sequence of images taken un...
     
Principles of appearance acquisition and representation
Found in: ACM SIGGRAPH 2008 classes (SIGGRAPH '08)
By Hendrik Lensch, Jason Lawrence, Szymon Rusinkiewicz, Tim Weyrich, Todd Zickler
Issue Date:August 2008
pp. 110-110
Algorithms for scene understanding and realistic image synthesis require accurate models of the way real-world materials scatter light. This class describes recent work in the graphics community to measure the spatially- and directionally-varying reflectan...
     
A perception-based color space for illumination-invariant image processing
Found in: ACM Transactions on Graphics (TOG)
By Hamilton Y. Chong, Steven J. Gortler, Todd Zickler
Issue Date:August 2008
pp. 1-49
Motivated by perceptual principles, we derive a new color space in which the associated metric approximates perceived distances and color displacements capture relationships that are robust to spectral changes in illumination. The resulting color space can...
     
Dichromatic separation: specularity removal and editing
Found in: ACM SIGGRAPH 2006 Sketches (SIGGRAPH '06)
By David Kriegman, Peter Belhumeur, Satya P. Mallick, Todd Zickler
Issue Date:July 2006
pp. 166-es
With the rise of web-based tagging systems, it has become important to help users search and browse the index of tags that are being created. One promising approach is visualization, but existing techniques rely on hard-to-interpret network diagrams or foc...
     
Dichromatic separation: specularity removal and editing
Found in: Material presented at the ACM SIGGRAPH 2006 conference (SIGGRAPH '06)
By David Kriegman, Peter Belhumeur, Satya P. Mallick, Todd Zickler
Issue Date:July 2006
pp. 166-es
With the rise of web-based tagging systems, it has become important to help users search and browse the index of tags that are being created. One promising approach is visualization, but existing techniques rely on hard-to-interpret network diagrams or foc...
     
 1