Abstract The visual medium evolved from early paintings to the realistic paintings of the classic... more Abstract The visual medium evolved from early paintings to the realistic paintings of the classical era to photographs. The medium of moving imagery started with motion pictures. Television and video recording advanced it to show action “live” or capture and playback later. In all of the above media, the view of the scene is determined at the transcription time, independent of the viewer. We have been developing a new visual medium called virtualized reality.
Abstract Compact representation of geometry using a suitable procedural or mathematical model and... more Abstract Compact representation of geometry using a suitable procedural or mathematical model and a ray-tracing mode of rendering fit the programmable graphics processor units (GPUs) well. Several such representations including parametric and subdivision surfaces have been explored in recent research. The important and widely applicable category of the general implicit surface has received less attention. In this paper, we present a ray-tracing procedure to render general implicit surfaces efficiently on the GPU.
Abstract Linear algebra algorithms are fundamental to many computing applications. Modern GPUs ar... more Abstract Linear algebra algorithms are fundamental to many computing applications. Modern GPUs are suited for many general purpose processing tasks and have emerged as inexpensive high performance co-processors due to their tremendous computing power. In this paper, we present the implementation of singular value decomposition (SVD) of a dense matrix on GPU using the CUDA programming model. SVD is implemented using the twin steps of bidiagonalization followed by diagonalization.
Intermodal (IM) trains are typically the fastest freight trains operated in North America. The ae... more Intermodal (IM) trains are typically the fastest freight trains operated in North America. The aerodynamic characteristics of many of these trains are often relatively poor resulting in high fuel consumption. However, considerable variation in fuel efficiency is possible depending on how the loads are placed on railcars in the train. Consequently, substantial potential fuel savings are possible if more attention is paid to the loading configuration of trains.
Abstract Graphics processing units provide a large computational power at a very low price which ... more Abstract Graphics processing units provide a large computational power at a very low price which position them as an ubiquitous accelerator. General purpose programming on the graphics processing units (GPGPU) is best suited for regular data parallel algorithms. They are not directly amenable for algorithms which have irregular data access patterns such as list ranking, and finding the connected components of a graph, and the like.
Abstract In this paper, we present the design and construction of a simple and inexpensive 3D dis... more Abstract In this paper, we present the design and construction of a simple and inexpensive 3D display made up of polygonal elements. We use a per-pixel transformation of image and depth to produce accurate picture and depth map on an arbitrary planar display facet from any viewpoint. Though the facets are rendered independently, the image and depth for rays from the eye-point through the facet pixels is produced by our method. Thus, there are no artifacts on a facet or at facet boundaries.
Abstract We address a few problems in navigation of automated vehicles using images captured by a... more Abstract We address a few problems in navigation of automated vehicles using images captured by a mounted camera. Specifically, we look at the recognition of sign boards, rectification of planar objects imaged by the camera and estimation of the position of a vehicle with respect to a fixed sign board. Our solutions are based on contour correspondence between a reference view and the current view.
Abstract We propose an object centric representation for easy and intuitive navigation and manipu... more Abstract We propose an object centric representation for easy and intuitive navigation and manipulation of videos. Object centric representation allows a user to directly access and process objects as basic video components. We demonstrate a trajectory based interface and example operations, which allow users to retime, reorder, remove or clone video objects in a'click and drag'fashion. This interface is created by extracting object motion information from the video.
Abstract We present a non-photo realistic, real-time painterly rendering technique for terrains. ... more Abstract We present a non-photo realistic, real-time painterly rendering technique for terrains. The painterly appearance and the impression of terrains is created by effectively rendering several brush strokes. The strokes have fixed locations on the surfaces of the terrain during animation to enable frame to frame coherency. The strokes are rendered as alpha blended sprites in two-dimensions and are oriented along the slope of terrain analogous to the way artists paint on canvas.
Abstract Many image filtering operations provide ample parallelism, but progressive non-linear pr... more Abstract Many image filtering operations provide ample parallelism, but progressive non-linear processing of images is among the hardest to parallelize due to long, sequential, and non-linear data dependency. A typical example of such an operation is error diffusion dithering, exemplified by the Floyd-Steinberg algorithm. In this paper, we present its parallelization on multicore CPUs using a block-based approach and on the GPU using a pixel based approach.
Abstract Graphics models are getting increasingly bulkier with detailed geometry, textures, norma... more Abstract Graphics models are getting increasingly bulkier with detailed geometry, textures, normal maps, etc. There is a lot of interest to model and navigate through detailed models of large monuments. Many monuments of interest have both rich detail and large spatial extent. Rendering them for navigation on a single workstation is practically impossible, even given the power of today's CPUs and GPUs. Many models may not fit the GPU memory, the CPU memory, or even the secondary storage of the CPU.
Abstract Displays have remained flat and passive amidst the many changes in their fundamental tec... more Abstract Displays have remained flat and passive amidst the many changes in their fundamental technologies. In this paper, we present a system to design, render to, and build view-dependent multiplanar displays, of arbitrary shape built using planar, polygonal facets. Our system provides high quality, interactive rendering of 3D environments to a head-tracked viewer on arbitrary planar display shapes. We develop a novel rendering scheme that creates exact image and depth at each display facet.
Abstract Video data is increasing rapidly along with the capacity of storage devices owned by a l... more Abstract Video data is increasing rapidly along with the capacity of storage devices owned by a lay user. Users have moderate to large personal collections of videos and would like to keep them in an organized manner based on its content. Video organizing tools for personal users are way behind even the primitive image organizing tools. We present a mechanism in this paper to help ordinary users organize their personal collection of videos based on categories they choose.
Abstract—Augmenting virtual objects between real objects of a video poses a challenging problem, ... more Abstract—Augmenting virtual objects between real objects of a video poses a challenging problem, primarily because it necessitates accurate knowledge of the scene's depth. In this paper, we propose an approach that generates an approximate depth for every pixel in the vicinity of the virtual object, which we show is enough to decide the ordering of objects in every image. We also draw a similarity between layered segmentation and augmentation.
Abstract A video from a moving camera produces different number of observations of different scen... more Abstract A video from a moving camera produces different number of observations of different scene areas. We can construct an attention map of the scene by bringing the frames to a common reference and counting the number of frames that observed each scene point. Different representations can be constructed from this. The base of the attention map gives the scene mosaic. Super-resolved images of parts of the scene can be obtained using a subset of observations or video frames.
Abstract Advances in cameras and web technology have made it easy to capture and share large amou... more Abstract Advances in cameras and web technology have made it easy to capture and share large amounts of video data over to a large number of people. A large number of cameras oversee public and semi-public spaces today. These raise concerns on the unintentional and unwarranted invasion of the privacy of individuals caught in the videos. To address these concerns, automated methods to de-identify individuals in these videos are necessary. De-identification does not aim at destroying all information involving the individuals.
Abstract—The Graphics Processing Units (GPUs) provide high computation power at a low cost and is... more Abstract—The Graphics Processing Units (GPUs) provide high computation power at a low cost and is an important compute accelerator with a massively multithreaded architecture. In this paper, we present fast implementations of common graph operations like breadth-first search, st-connectivity, single-source shortest path, all-pairs shortest path, minimum spanning tree, and maximum flow for undirected graphs on the GPU using the CUDA programming model.
Abstract Graph cuts has become a powerful and popular optimization tool for energies defined over... more Abstract Graph cuts has become a powerful and popular optimization tool for energies defined over an MRF and have found applications in image segmentation, stereo vision, image restoration, etc. The maxflow/mincut algorithm to compute graph-cuts is computationally heavy. The best-reported implementation of graph cuts takes over 100 milliseconds even on images of size 640times480 and cannot be used for real-time applications or when iterated applications are needed.
Abstract: Several applications today need to digitally capture every frame of a video stream or a... more Abstract: Several applications today need to digitally capture every frame of a video stream or a camera. These range from psychological studies to surveillance to video processing. Some applications also need to capture the fames from multiple video streams synchronously and to correlate them with one another. A video stream of color data, though, represents a sustained bandwidth of about 26 Mbytes per second from the digitizing hardware to a secondary storage service without compression.
Abstract Despite significant progress in automatic recovery of static scene structure from range ... more Abstract Despite significant progress in automatic recovery of static scene structure from range images, little effort has been made toward extending these approaches to dynamic scenes. This disparity is in large part due to the lack of range sensors with the high sampling rates needed to accurately capture dynamic scenes.
Abstract The visual medium evolved from early paintings to the realistic paintings of the classic... more Abstract The visual medium evolved from early paintings to the realistic paintings of the classical era to photographs. The medium of moving imagery started with motion pictures. Television and video recording advanced it to show action “live” or capture and playback later. In all of the above media, the view of the scene is determined at the transcription time, independent of the viewer. We have been developing a new visual medium called virtualized reality.
Abstract Compact representation of geometry using a suitable procedural or mathematical model and... more Abstract Compact representation of geometry using a suitable procedural or mathematical model and a ray-tracing mode of rendering fit the programmable graphics processor units (GPUs) well. Several such representations including parametric and subdivision surfaces have been explored in recent research. The important and widely applicable category of the general implicit surface has received less attention. In this paper, we present a ray-tracing procedure to render general implicit surfaces efficiently on the GPU.
Abstract Linear algebra algorithms are fundamental to many computing applications. Modern GPUs ar... more Abstract Linear algebra algorithms are fundamental to many computing applications. Modern GPUs are suited for many general purpose processing tasks and have emerged as inexpensive high performance co-processors due to their tremendous computing power. In this paper, we present the implementation of singular value decomposition (SVD) of a dense matrix on GPU using the CUDA programming model. SVD is implemented using the twin steps of bidiagonalization followed by diagonalization.
Intermodal (IM) trains are typically the fastest freight trains operated in North America. The ae... more Intermodal (IM) trains are typically the fastest freight trains operated in North America. The aerodynamic characteristics of many of these trains are often relatively poor resulting in high fuel consumption. However, considerable variation in fuel efficiency is possible depending on how the loads are placed on railcars in the train. Consequently, substantial potential fuel savings are possible if more attention is paid to the loading configuration of trains.
Abstract Graphics processing units provide a large computational power at a very low price which ... more Abstract Graphics processing units provide a large computational power at a very low price which position them as an ubiquitous accelerator. General purpose programming on the graphics processing units (GPGPU) is best suited for regular data parallel algorithms. They are not directly amenable for algorithms which have irregular data access patterns such as list ranking, and finding the connected components of a graph, and the like.
Abstract In this paper, we present the design and construction of a simple and inexpensive 3D dis... more Abstract In this paper, we present the design and construction of a simple and inexpensive 3D display made up of polygonal elements. We use a per-pixel transformation of image and depth to produce accurate picture and depth map on an arbitrary planar display facet from any viewpoint. Though the facets are rendered independently, the image and depth for rays from the eye-point through the facet pixels is produced by our method. Thus, there are no artifacts on a facet or at facet boundaries.
Abstract We address a few problems in navigation of automated vehicles using images captured by a... more Abstract We address a few problems in navigation of automated vehicles using images captured by a mounted camera. Specifically, we look at the recognition of sign boards, rectification of planar objects imaged by the camera and estimation of the position of a vehicle with respect to a fixed sign board. Our solutions are based on contour correspondence between a reference view and the current view.
Abstract We propose an object centric representation for easy and intuitive navigation and manipu... more Abstract We propose an object centric representation for easy and intuitive navigation and manipulation of videos. Object centric representation allows a user to directly access and process objects as basic video components. We demonstrate a trajectory based interface and example operations, which allow users to retime, reorder, remove or clone video objects in a'click and drag'fashion. This interface is created by extracting object motion information from the video.
Abstract We present a non-photo realistic, real-time painterly rendering technique for terrains. ... more Abstract We present a non-photo realistic, real-time painterly rendering technique for terrains. The painterly appearance and the impression of terrains is created by effectively rendering several brush strokes. The strokes have fixed locations on the surfaces of the terrain during animation to enable frame to frame coherency. The strokes are rendered as alpha blended sprites in two-dimensions and are oriented along the slope of terrain analogous to the way artists paint on canvas.
Abstract Many image filtering operations provide ample parallelism, but progressive non-linear pr... more Abstract Many image filtering operations provide ample parallelism, but progressive non-linear processing of images is among the hardest to parallelize due to long, sequential, and non-linear data dependency. A typical example of such an operation is error diffusion dithering, exemplified by the Floyd-Steinberg algorithm. In this paper, we present its parallelization on multicore CPUs using a block-based approach and on the GPU using a pixel based approach.
Abstract Graphics models are getting increasingly bulkier with detailed geometry, textures, norma... more Abstract Graphics models are getting increasingly bulkier with detailed geometry, textures, normal maps, etc. There is a lot of interest to model and navigate through detailed models of large monuments. Many monuments of interest have both rich detail and large spatial extent. Rendering them for navigation on a single workstation is practically impossible, even given the power of today's CPUs and GPUs. Many models may not fit the GPU memory, the CPU memory, or even the secondary storage of the CPU.
Abstract Displays have remained flat and passive amidst the many changes in their fundamental tec... more Abstract Displays have remained flat and passive amidst the many changes in their fundamental technologies. In this paper, we present a system to design, render to, and build view-dependent multiplanar displays, of arbitrary shape built using planar, polygonal facets. Our system provides high quality, interactive rendering of 3D environments to a head-tracked viewer on arbitrary planar display shapes. We develop a novel rendering scheme that creates exact image and depth at each display facet.
Abstract Video data is increasing rapidly along with the capacity of storage devices owned by a l... more Abstract Video data is increasing rapidly along with the capacity of storage devices owned by a lay user. Users have moderate to large personal collections of videos and would like to keep them in an organized manner based on its content. Video organizing tools for personal users are way behind even the primitive image organizing tools. We present a mechanism in this paper to help ordinary users organize their personal collection of videos based on categories they choose.
Abstract—Augmenting virtual objects between real objects of a video poses a challenging problem, ... more Abstract—Augmenting virtual objects between real objects of a video poses a challenging problem, primarily because it necessitates accurate knowledge of the scene's depth. In this paper, we propose an approach that generates an approximate depth for every pixel in the vicinity of the virtual object, which we show is enough to decide the ordering of objects in every image. We also draw a similarity between layered segmentation and augmentation.
Abstract A video from a moving camera produces different number of observations of different scen... more Abstract A video from a moving camera produces different number of observations of different scene areas. We can construct an attention map of the scene by bringing the frames to a common reference and counting the number of frames that observed each scene point. Different representations can be constructed from this. The base of the attention map gives the scene mosaic. Super-resolved images of parts of the scene can be obtained using a subset of observations or video frames.
Abstract Advances in cameras and web technology have made it easy to capture and share large amou... more Abstract Advances in cameras and web technology have made it easy to capture and share large amounts of video data over to a large number of people. A large number of cameras oversee public and semi-public spaces today. These raise concerns on the unintentional and unwarranted invasion of the privacy of individuals caught in the videos. To address these concerns, automated methods to de-identify individuals in these videos are necessary. De-identification does not aim at destroying all information involving the individuals.
Abstract—The Graphics Processing Units (GPUs) provide high computation power at a low cost and is... more Abstract—The Graphics Processing Units (GPUs) provide high computation power at a low cost and is an important compute accelerator with a massively multithreaded architecture. In this paper, we present fast implementations of common graph operations like breadth-first search, st-connectivity, single-source shortest path, all-pairs shortest path, minimum spanning tree, and maximum flow for undirected graphs on the GPU using the CUDA programming model.
Abstract Graph cuts has become a powerful and popular optimization tool for energies defined over... more Abstract Graph cuts has become a powerful and popular optimization tool for energies defined over an MRF and have found applications in image segmentation, stereo vision, image restoration, etc. The maxflow/mincut algorithm to compute graph-cuts is computationally heavy. The best-reported implementation of graph cuts takes over 100 milliseconds even on images of size 640times480 and cannot be used for real-time applications or when iterated applications are needed.
Abstract: Several applications today need to digitally capture every frame of a video stream or a... more Abstract: Several applications today need to digitally capture every frame of a video stream or a camera. These range from psychological studies to surveillance to video processing. Some applications also need to capture the fames from multiple video streams synchronously and to correlate them with one another. A video stream of color data, though, represents a sustained bandwidth of about 26 Mbytes per second from the digitizing hardware to a secondary storage service without compression.
Abstract Despite significant progress in automatic recovery of static scene structure from range ... more Abstract Despite significant progress in automatic recovery of static scene structure from range images, little effort has been made toward extending these approaches to dynamic scenes. This disparity is in large part due to the lack of range sensors with the high sampling rates needed to accurately capture dynamic scenes.
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Papers by P J Narayanan