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Displaying 1-50 out of 148 total
NETRA: interactive display for estimating refractive errors and focal range
Found in: ACM Transactions on Graphics (TOG)
By Ankit Mohan, Manuel M. Oliveira, Ramesh Raskar, Vitor F. Pamplona, Ankit Mohan, Manuel M. Oliveira, Ramesh Raskar, Vitor F. Pamplona, Ankit Mohan, Manuel M. Oliveira, Ramesh Raskar, Vitor F. Pamplona, Ankit Mohan, Manuel M. Oliveira, Ramesh Raskar, Vitor F. Pamplona
Issue Date:July 2010
pp. 1-10
We introduce an interactive, portable, and inexpensive solution for estimating refractive errors in the human eye. While expensive optical devices for automatic estimation of refractive correction exist, our goal is to greatly simplify the mechanism by put...
     
Bokode: imperceptible visual tags for camera based interaction from a distance
Found in: ACM Transactions on Graphics (TOG)
By Ankit Mohan, Grace Woo, Quinn Smithwick, Ramesh Raskar, Shinsaku Hiura, Ankit Mohan, Grace Woo, Quinn Smithwick, Ramesh Raskar, Shinsaku Hiura, Ankit Mohan, Grace Woo, Quinn Smithwick, Ramesh Raskar, Shinsaku Hiura, Ankit Mohan, Grace Woo, Quinn Smithwick, Ramesh Raskar, Shinsaku Hiura
Issue Date:July 2009
pp. 1-2
We show a new camera based interaction solution where an ordinary camera can detect small optical tags from a relatively large distance. Current optical tags, such as barcodes, must be read within a short range and the codes occupy valuable physical space ...
     
Invertible motion blur in video
Found in: ACM Transactions on Graphics (TOG)
By Amit Agrawal, Ramesh Raskar, Yi Xu, Amit Agrawal, Ramesh Raskar, Yi Xu, Amit Agrawal, Ramesh Raskar, Yi Xu, Amit Agrawal, Ramesh Raskar, Yi Xu
Issue Date:July 2009
pp. 1-2
We show that motion blur in successive video frames is invertible even if the point-spread function (PSF) due to motion smear in a single photo is non-invertible. Blurred photos exhibit nulls (zeros) in the frequency transform of the PSF, leading to an ill...
     
Table-Top Spatially-Augmented Reality: Bringing Physical Models to Life with Projected Imagery
Found in: Augmented Reality, International Workshop on
By Ramesh Raskar, Greg Welch, Wei-Chao Chen
Issue Date:October 1999
pp. 64
Despite the availability of high-quality graphics systems, architects and designers still build scaled physical models of buildings and products. These physical models have many advantages, however they are typically static in structure and surface charact...
 
Keynote speeches - The poor man's palace: special effects in the real world / Do we have six brains?
Found in: Mixed and Augmented Reality, IEEE / ACM International Symposium on
By Ramesh Raskar, Thomas Furness
Issue Date:October 2006
pp. xxii-xxiii
No summary available.
   
Single view reflectance capture using multiplexed scattering and time-of-flight imaging
Found in: ACM Transactions on Graphics (TOG)
By Andreas Velten, Kavita Bala, Nikhil Naik, Ramesh Raskar, Shuang Zhao, Andreas Velten, Kavita Bala, Nikhil Naik, Ramesh Raskar, Shuang Zhao
Issue Date:December 2011
pp. 1-15
This paper introduces the concept of time-of-flight reflectance estimation, and demonstrates a new technique that allows a camera to rapidly acquire reflectance properties of objects from a single view-point, over relatively long distances and without enci...
     
Axial-cones: modeling spherical catadioptric cameras for wide-angle light field rendering
Found in: ACM Transactions on Graphics (TOG)
By Amit Agrawal, Ashok Veeraraghavan, Ramesh Raskar, Srikumar Ramalingam, Yuichi Taguchi, Amit Agrawal, Ashok Veeraraghavan, Ramesh Raskar, Srikumar Ramalingam, Yuichi Taguchi
Issue Date:December 2010
pp. 1-12
Catadioptric imaging systems are commonly used for wide-angle imaging, but lead to multi-perspective images which do not allow algorithms designed for perspective cameras to be used. Efficient use of such systems requires accurate geometric ray modeling as...
     
Content-adaptive parallax barriers: optimizing dual-layer 3D displays using low-rank light field factorization
Found in: ACM Transactions on Graphics (TOG)
By Douglas Lanman, Matthew Hirsch, Ramesh Raskar, Yunhee Kim, Douglas Lanman, Matthew Hirsch, Ramesh Raskar, Yunhee Kim
Issue Date:December 2010
pp. 1-12
We optimize automultiscopic displays built by stacking a pair of modified LCD panels. To date, such dual-stacked LCDs have used heuristic parallax barriers for view-dependent imagery: the front LCD shows a fixed array of slits or pinholes, independent of t...
     
BiDi screen: a thin, depth-sensing LCD for 3D interaction using light fields
Found in: ACM Transactions on Graphics (TOG)
By Douglas Lanman, Henry Holtzman, Matthew Hirsch, Ramesh Raskar, Douglas Lanman, Henry Holtzman, Matthew Hirsch, Ramesh Raskar
Issue Date:December 2009
pp. 1-2
We transform an LCD into a display that supports both 2D multi-touch and unencumbered 3D gestures. Our BiDirectional (BiDi) screen, capable of both image capture and display, is inspired by emerging LCDs that use embedded optical sensors to detect multiple...
     
VRCodes: Unobtrusive and active visual codes for interaction by exploiting rolling shutter
Found in: 2012 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)
By Grace Woo,Andy Lippman,Ramesh Raskar
Issue Date:November 2012
pp. 59-64
We show a new visible tagging solution for active displays which allows a rolling-shutter camera to detect active tags from a relatively large distance in a robust manner. Current planar markers are visually obtrusive for the human viewer. In order for the...
 
Refractive shape from light field distortion
Found in: Computer Vision, IEEE International Conference on
By Gordon Wetzstein,David Roodnick,Wolfgang Heidrich,Ramesh Raskar
Issue Date:November 2011
pp. 1180-1186
Acquiring transparent, refractive objects is challenging as these kinds of objects can only be observed by analyzing the distortion of reference background patterns. We present a new, single image approach to reconstructing thin transparent surfaces, such ...
 
Analysis of light transport in scattering media
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Yasuhiro Mukaigawa, Yasushi Yagi, Ramesh Raskar
Issue Date:June 2010
pp. 153-160
We propose a new method to analyze light transport in homogeneous scattering media. The incident light undergoes multiple bounces in translucent objects, and produces a complex light field. Our method analyzes the light transport in two steps. First, singl...
 
Coded Strobing Photography: Compressive Sensing of High Speed Periodic Videos
Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence
By Ashok Veeraraghavan, Dikpal Reddy, Ramesh Raskar
Issue Date:April 2011
pp. 671-686
We show that, via temporal modulation, one can observe and capture a high-speed periodic video well beyond the abilities of a low-frame-rate camera. By strobing the exposure with unique sequences within the integration time of each frame, we take coded pro...
 
A Unified Calibration Method with a Parametric Approach for Wide-Field-of-View Multiprojector Displays
Found in: Virtual Reality Conference, IEEE
By Masato Ogata, Hiroyuki Wada, Jeroen van Baar, Ramesh Raskar
Issue Date:March 2009
pp. 235-236
In this paper, we describe techniques for supporting a wide-field-of-view multiprojector curved screen display system. Our main contribution is in achieving automatic geometric calibration and efficient rendering for seamless displays, which is effective e...
 
Characterizing the shadow space of camera-light pairs
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Daniel A. Vaquero, Rogerio S. Feris, Matthew Turk, Ramesh Raskar
Issue Date:June 2008
pp. 1-8
We present a theoretical analysis for characterizing the shadows cast by a point light source given its relative position to the camera. In particular, we analyze the epipolar geometry of camera-light pairs, including unusual camera-light configurations su...
 
Non-refractive modulators for encoding and capturing scene appearance and depth
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Ashok Veeraraghavan, Amit Agrawal, Ramesh Raskar, Ankit Mohan, Jack Tumblin
Issue Date:June 2008
pp. 1-8
We analyze the modulation of a light field via non-refracting attenuators. In the most general case, any desired modulation can be achieved with attenuators having four degrees of freedom in ray-space. We motivate the discussion with a universal 4D ray mod...
 
Sensing increased image resolution using aperture masks
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Ankit Mohan, Xiang Huang, Jack Tumblin, Ramesh Raskar
Issue Date:June 2008
pp. 1-8
We present a technique to construct increased-resolution images from multiple photos taken without moving the camera or the sensor. Like other super-resolution techniques, we capture and merge multiple images, but instead of moving the camera sensor by sub...
 
Multiflash Stereopsis: Depth-Edge-Preserving Stereo with Small Baseline Illumination
Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence
By Rogerio Feris, Ramesh Raskar, Longbin Chen, Karhan Tan, Matthew Turk
Issue Date:January 2008
pp. 147-159
Traditional stereo matching algorithms are limited in their ability to produce accurate results near depth discontinuities, due to partial occlusions and violation of smoothness constraints. In this paper, we use small baseline multi-flash illumination to ...
 
Resolving Objects at Higher Resolution from a Single Motion-blurred Image
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Amit Agrawal, Ramesh Raskar
Issue Date:June 2007
pp. 1-8
Motion blur can degrade the quality of images and is considered a nuisance for computer vision problems. In this paper, we show that motion blur can in-fact be used for increasing the resolution of a moving object. Our approach utilizes the information in ...
 
Dealing with Multi-Scale Depth Changes and Motion in Depth Edge Detection
Found in: Graphics, Patterns and Images, SIBGRAPI Conference on
By Rogerio Feris, Matthew Turk, Ramesh Raskar
Issue Date:October 2006
pp. 3-10
Sharp discontinuities in depth, or depth edges, are very important low-level features for scene understanding. Recently, we have proposed a solution to the depth edge detection problem using a simple modification of the capture setup: a multi-flash camera ...
 
Edge Suppression by Gradient Field Transformation Using Cross-Projection Tensors
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Amit Agrawal, Ramesh Raskar, Rama Chellappa
Issue Date:June 2006
pp. 2301-2308
We propose a new technique for edge-suppressing operations on images. We introduce cross projection tensors to achieve affine transformations of gradient fields. We use these tensors, for example, to remove edges in one image based on the edge-information ...
 
Tags are Coming: Exploiting Photosensing Wireless Tags for Assisting Geometric Procedures
Found in: Computer Vision for Interactive and Intelligent Environment
By Ramesh Raskar, Paul Beardsley, Paul Dietz, Jeroen Van Baar
Issue Date:November 2005
pp. 145-150
Radio frequency tags allow objects to become self-describing, communicating their identity to a close at hand RF reader. Our goal is to build a radio frequency identity and geometry (RFIG) transponder that can also communicate geometry, inter-tag location ...
 
Discontinuity Preserving Stereo with Small Baseline Multi-Flash Illumination
Found in: Computer Vision, IEEE International Conference on
By Rogerio Feris, Ramesh Raskar, Longbin Chen, Kar-Han Tan, Matthew Turk
Issue Date:October 2005
pp. 412-419
Currently, sharp discontinuities in depth and partial occlusions in multiview imaging systems pose serious challenges for many dense correspondence algorithms. However, it is important for 3D reconstruction methods to preserve depth edges as they correspon...
 
An Algebraic Approach to Surface Reconstruction from Gradient Fields
Found in: Computer Vision, IEEE International Conference on
By Amit Agrawal, Rama Chellappa, Ramesh Raskar
Issue Date:October 2005
pp. 174-181
Several important problems in computer vision such as Shape from Shading (SFS) and Photometric Stereo (PS) require reconstructing a surface from an estimated gradient field, which is usually non-integrable, i.e. have non-zero curl. We propose a purely alge...
 
Videoshop: A New Framework for Spatio-Temporal Video Editing in Gradient Domain
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Hongcheng Wang, Ning Xu, Ramesh Raskar, Narendra Ahuja
Issue Date:June 2005
pp. 1201
No summary available.
   
Handheld Projectors for Mixing Physical and Digital Textures
Found in: Computer Vision and Pattern Recognition Workshop
By Paul Beardsley, Clifton Forlines, Ramesh Raskar, Jeroen VanBaar
Issue Date:June 2005
pp. 112
<p>Handheld projectors offer a new type of display modality, not tied to a physical screen or to a fixed projection area, yet providing a larger display than is available from a handheld device with fixed screen. This paper begins with a review of ou...
 
Why I Want a Gradient Camera
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Jack Tumblin, Amit Agrawal, Ramesh Raskar
Issue Date:June 2005
pp. 103-110
We propose a camera that measures static gradients instead of static intensities. Quantizing sensed intensity differences between adjacent pixel values permits an ordinary A/D converter to measure detailed high contrast (HDR) scenes. We measure alternating...
 
Harnessing Real-World Depth Edges with Multiflash Imaging
Found in: IEEE Computer Graphics and Applications
By Ramesh Raskar, Kar-Han Tan, Rogerio S. Feris, Matthew Turk, James Kobler, Jingyi Yu
Issue Date:January 2005
pp. 32-38
A method for capturing geometric features of real-world scenes relies on a simple modification of the capture setup: A multiflash camera is used with flashes strategically positioned to cast shadows along depth discontinuities in the scene, allowing effici...
 
Interaction Using a Handheld Projector
Found in: IEEE Computer Graphics and Applications
By Paul Beardsley, Jeroen Van Baar, Ramesh Raskar, Clifton Forlines
Issue Date:January 2005
pp. 39-43
Interactive projection shows that handheld projection is a practical and useful addition to mobile computing. Two aspects of the work, familiar from different areas of the existing literature, are keystone correction to remove warping effects when the proj...
 
Specular Reflection Reduction with Multi-Flash Imaging
Found in: Graphics, Patterns and Images, SIBGRAPI Conference on
By Rogerio Feris, Ramesh Raskar, Kar-Han Tan, Matthew Turk
Issue Date:October 2004
pp. 316-321
We present a novel method to reduce the effect of specularities in digital images. Our approach relies on a simple modification of the capture setup: a multi-flash camera is used to take multiple pictures of the scene, each one with a differently positione...
 
Seamless Video Editing
Found in: Pattern Recognition, International Conference on
By Hongcheng Wang, Ramesh Raskar, Narendra Ahuja
Issue Date:August 2004
pp. 858-861
This paper presents a new framework for seamless video editing in the gradient domain. The spatio-temporal gradient fields of target videos are modified or mixed to generate a new gradient field, which is usually not integrable. We propose a 3D video integ...
 
Exploiting Depth Discontinuities for Vision-Based Fingerspelling Recognition
Found in: Computer Vision and Pattern Recognition Workshop
By Rogerio Feris, Matthew Turk, Ramesh Raskar, Karhan Tan, Gosuke Ohashi
Issue Date:July 2004
pp. 155
We present a novel method for automatic fingerspelling recognition which is able to discriminate complex hand configurations with high amounts of finger occlusions. Such a scenario, while common in most fingerspelling alphabets, presents a challenge for vi...
 
Blending Multiple Views
Found in: Computer Graphics and Applications, Pacific Conference on
By Ramesh Raskar, Kok-Lim Low
Issue Date:October 2002
pp. 145
<p>Current blending methods in image-based rendering use local information such as
 
Merging Fossil Specimens with Computer-Generated Information
Found in: Computer
By Oliver Bimber, Stephen M. Gatesy, Lawrence M. Witmer, Ramesh Raskar, L. Miguel Encarnação
Issue Date:September 2002
pp. 25-30
<p>While dinosaur fossils reveal much, they keep us guessing about the original organisms' color, sound, and behavior. For several years, modern paleontologists have used 3D computer graphics to help reconstruct these pieces of the past. Augmented re...
 
A Self-Correcting Projector
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Ramesh Raskar, Paul Beardsley
Issue Date:December 2001
pp. 504
We describe a calibration and rendering technique for a projector that can render rectangular images under keystoned position. The projector utilizes a rigidly attached camera to form a stereo pair. We describe a very easy to use technique for calibration ...
 
Dynamic Shader Lamps: Painting on Movable Objects
Found in: Augmented Reality, International Symposium on
By Deepak Bandyopadhyay, Ramesh Raskar, Henry Fuchs
Issue Date:October 2001
pp. 207
We present a Dynamic Spatially Augmented Reality system for augmenting movable 3D objects in an indoor environment using multiple projectors. We describe a real-time system for applying virtual paint and textures to real objects simply by direct physical m...
 
Projected Imagery in Your
Found in: IEEE Computer Graphics and Applications
By Greg Welch, Henry Fuchs, Ramesh Raskar, Herman Towles, Michael S. Brown
Issue Date:July 2000
pp. 62-67
Someday, high-resolution projected imagery will surround you in your office. The walls, your desk, and even the floor will serve as your computer desktop. Our dream is that your office will have ceiling-mounted digital cameras and projectors that work toge...
 
Immersive Planar Display Using Roughly Aligned Projectors
Found in: Virtual Reality Conference, IEEE
By Ramesh Raskar
Issue Date:March 2000
pp. 109
When a projector is oblique with respect to a planar display surface, it creates keystoning and the projected image is distorted. We present a rendering technique to display perspectively correct images for a moving user. This allows using roughly aligned ...
 
Multi-Projector Displays Using Camera-Based Registration
Found in: Visualization Conference, IEEE
By Ramesh Raskar, Michael S. Brown, Ruigang Yang, Wei-Chao Chen, Greg Welch, Herman Towles, Brent Seales, Henry Fuchs
Issue Date:October 1999
pp. 26
<div>Conventional projector-based display systems are typically designed around precise and regular configurations of projectors and display surfaces. While this results in rendering simplicity and speed, it also means painstaking construction and on...
 
Skin perfusion photography
Found in: 2014 IEEE International Conference on Computational Photography (ICCP)
By Guy Satat,Christopher Barsi,Ramesh Raskar
Issue Date:May 2014
pp. 1-8
The separation of global and direct light components of a scene is highly useful for scene analysis, as each component offers different information about illumination-scene-detector interactions. Relying on ray optics, the technique is important in computa...
   
A switchable light field camera architecture with Angle Sensitive Pixels and dictionary-based sparse coding
Found in: 2014 IEEE International Conference on Computational Photography (ICCP)
By Matthew Hirsch,Sriram Sivaramakrishnan,Suren Jayasuriya,Albert Wang,Alyosha Molnar,Ramesh Raskar,Gordon Wetzstein
Issue Date:May 2014
pp. 1-10
We propose a flexible light field camera architecture that is at the convergence of optics, sensor electronics, and applied mathematics. Through the co-design of a sensor that comprises tailored, Angle Sensitive Pixels and advanced reconstruction algorithm...
   
Demultiplexing illumination via low cost sensing and nanosecond coding
Found in: 2014 IEEE International Conference on Computational Photography (ICCP)
By Achuta Kadambi,Ayush Bhandari,Refael Whyte,Adrian Dorrington,Ramesh Raskar
Issue Date:May 2014
pp. 1-10
Several computer vision algorithms require a sequence of photographs taken in different illumination conditions, which has spurred development in the area of illumination multiplexing. Various techniques for optimizing the multiplexing process already exis...
   
Phase messaging method for time-of-flight cameras
Found in: 2014 IEEE International Conference on Computational Photography (ICCP)
By Wenjia Yuan,Richard E. Howard,Kristin J. Dana,Ramesh Raskar,Ashwin Ashok,Marco Gruteser,Narayan Mandayam
Issue Date:May 2014
pp. 1-8
Ubiquitous light emitting devices and low-cost commercial digital cameras facilitate optical wireless communication system such as visual MIMO where handheld cameras communicate with electronic displays. While intensity-based optical communications are mor...
   
Discovering the Structure of a Planar Mirror System from Multiple Observations of a Single Point
Found in: 2013 IEEE Conference on Computer Vision and Pattern Recognition (CVPR)
By Ilya Reshetouski,Alkhazur Manakov,Ayush Bandhari,Ramesh Raskar,Hans-Peter Seidel,Ivo Ihrke
Issue Date:June 2013
pp. 89-96
We investigate the problem of identifying the position of a viewer inside a room of planar mirrors with unknown geometry in conjunction with the room's shape parameters. We consider the observations to consist of angularly resolved depth measurements of a ...
 
Coded focal stack photography
Found in: 2013 IEEE International Conference on Computational Photography (ICCP)
By Xing Lin,Jinli Suo,Gordon Wetzstein,Qionghai Dai,Ramesh Raskar
Issue Date:April 2013
pp. 1-9
We present coded focal stack photography as a computational photography paradigm that combines a focal sweep and a coded sensor readout with novel computational algorithms. We demonstrate various applications of coded focal stacks, including photography wi...
   
High-rank coded aperture projection for extended depth of field
Found in: 2013 IEEE International Conference on Computational Photography (ICCP)
By Chenguang Ma,Jinli Suo,Qionghai Dai,Ramesh Raskar,Gordon Wetzstein
Issue Date:April 2013
pp. 1-9
Projectors require large apertures to maximize light throughput. Unfortunately, this leads to shallow depths of field (DOF), hence blurry images, when projecting on non-planar surfaces, such as cultural heritage sites, curved screens, or when sharing visua...
   
Second Skin: Motion capture with actuated feedback for motor learning
Found in: Virtual Reality Conference, IEEE
By Dennis Miaw,Ramesh Raskar
Issue Date:March 2010
pp. 289-290
Second Skin aims to combine three-dimensional motion tracking with real-time tactile feedback for the purpose of improving a user's motor-learning ability. Body and limb movements are tracked in 3D as a user performs an action, and the user is given automa...
 
Coded time of flight cameras: sparse deconvolution to address multipath interference and recover time profiles
Found in: ACM Transactions on Graphics (TOG)
By Achuta Kadambi, Ayush Bhandari, Adrian Dorrington, Christopher Barsi, Lee Streeter, Ramesh Raskar, Refael Whyte
Issue Date:November 2013
pp. 1-10
Time of flight cameras produce real-time range maps at a relatively low cost using continuous wave amplitude modulation and demodulation. However, they are geared to measure range (or phase) for a single reflected bounce of light and suffer from systematic...
     
Focus 3D: Compressive accommodation display
Found in: ACM Transactions on Graphics (TOG)
By Andrew Maimone, Douglas Lanman, Gordon Wetzstein, Henry Fuchs, Matthew Hirsch, Ramesh Raskar
Issue Date:September 2013
pp. 1-13
We present a glasses-free 3D display design with the potential to provide viewers with nearly correct accommodative depth cues, as well as motion parallax and binocular cues. Building on multilayer attenuator and directional backlight architectures, the pr...
     
Multifrequency time of flight in the context of transient renderings
Found in: ACM SIGGRAPH 2013 Posters (SIGGRAPH '13)
By Achuta Kadambi, Adrian Dorrington, Ayush Bhandari, Christopher Barsi, Lee Streeter, Ramesh Raskar, Refael Whyte
Issue Date:July 2013
pp. 1-1
The emergence of commercial time of flight (ToF) cameras for realtime depth images has motivated extensive study of exploitation of ToF information. In principle, a ToF camera is an active sensor that emits an amplitude modulated near-infrared (NIR) signal...
     
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