18462898
Rendering with Non-uniform Approximate Concentric Mosaics
In this paper, we explore the more practical aspects of building and rendering concentric mosaics. First, we use images captured with only approximately circular camera trajectories. The image sequence capture can be achieved by holding a camcorder in position and rotating the body all around. In addition, we investigate the use of variable input sampling and fidelity of scene geometry based on the level of interest (and hence quality of view synthesized) on the objects in the scene. We achieve the tolerance for minor perturbations about the exact circular camera path and variable input sampling by using and analyzing a variant of the Hough space of all captured rays. Examples using real scenes are shown to validate our approach.
16190492
Noise Estimation from a Single Image
In order to work well, many computer vision algorithms require that their parameters be adjusted according to the image noise level, making it an important quantity to estimate. We show how to estimate an upper bound on the noise level from a single image based on a piecewise smooth image prior model and measured CCD camera response functions. We also learn the space of noise level functions how noise level changes with respect to brightness and use Bayesian MAP inference to infer the noise level function from a single image. We illustrate the utility of this noise estimation for two algorithms: edge detection and featurepreserving smoothing through bilateral filtering. For a variety of different noise levels, we obtain good results for both these algorithms with no user-specified inputs.
47117010
Stylizing 2.5-D video
In recent years considerable interest has been given to non-photorealistic rendering of photographs, video, and 3D models for illustrative or artistic purposes. Conventional 2D inputs such as photographs and video are easy to create and capture, while 3D models allow for a wider variety of stylization techniques, such as cross-hatching. In this paper, we propose using video with depth information (2.5-D video) to combine the advantages of 2D and 3D input. 2.5-D video is becoming increasingly easy to capture, and with the additional depth information, stylization techniques that require shape information can be applied. However, because 2.5-D video contains only limited shape information and 3D correspondence over time is unknown, it is difficult to create temporally coherent stylized animations directly from raw 2.5-D video. In this paper, we present techniques for processing 2.5-D video to overcome these drawbacks, and demonstrate several styles that can be created using these techniques.
44673585
Characterization of Errors in Compositing Panoramic Images
A panoramic image has a 360° horizontal field of view, and it can provide the viewer the impression of being immersed in the scene. A panorama is created by first taking a sequence of images while rotating the camera about a vertical axis. These images are then projected onto a cylindrical surface before being seamlessly composited. The cross-sectional circumference of the cylindrical panorama is called thecompositing length. This work characterizes the error in compositing panoramic images due to errors in some of the intrinsic parameters. The intrinsic camera parameters that are considered are the camera focal length and the radial distortion coefficient. We show that the error in the compositing length is more sensitive to the error in the camera focal length. Especially important is the discovery that the relative error in compositing length is always smaller than the relative error in the focal length. This means that the error in focal length can be corrected by iteratively using the composited length to compute a new and more correct focal length. Thiscompositing approach to camera calibrationhas the advantages of not requiring both feature detection and separate prior calibration.
2096181
Video editing using figure tracking and image-based rendering
We describe a new approach to video editing based on the semi-automatic segmentation of video into multiple layers and the composition of layers using image-based rendering. Using figure tracking and background motion estimation, we can segment a moving figure and reconstruct the background. Using geometrically-correct pixel reprojection, layers can be composited on the basis of the geometry of the underlying scene and the position of a virtual camera. We have implemented a prototype editing system called SpliceWorld.
40596005
Survey of image-based representations and compression techniques
We survey the techniques for image-based rendering (IBR) and for compressing image-based representations. Unlike traditional three-dimensional (3-D) computer graphics, in which 3-D geometry of the scene is known, IBR techniques render novel views directly from input images. IBR techniques can be classified into three categories according to how much geometric information is used: rendering without geometry, rendering with implicit geometry (i.e., correspondence), and rendering with explicit geometry (either with approximate or accurate geometry). We discuss the characteristics of these categories and their representative techniques. IBR techniques demonstrate a surprising diverse range in their extent of use of images and geometry in representing 3-D scenes. We explore the issues in trading off the use of images and geometry by revisiting plenoptic-sampling analysis and the notions of view dependency and geometric proxies. Finally, we highlight compression techniques specifically designed for image-based representations. Such compression techniques are important in making IBR techniques practical.
8573619
NMOS energy recovery logic
In this paper, we describe NMOS Energy Recovery Logic (NERL) which exhibits high throughput with low energy consumption due to efficient energy transfer and recovery using adiabatic and bootstrapping techniques. NERL shows full output voltage swing, insensitivity to output load capacitance, less dependency on power-clock frequency and complementary outputs for balanced capacitance load to power-clock. We have designed an 8-bit CLA and inverter chain using 0.6 /spl mu/m CMOS technology and verified that NERL saves energy over ECRL by 2 to 3 times.
35282259
New algorithms for circuit simulation of device breakdown
Numerical algorithms that enable extension of device models into avalanche breakdown region without disturbing the convergence of modified nodal-analysis-based circuit simulators are introduced. Details of model implementation into circuit simulators are presented along with applications. In particular, circuit-level simulation of nondestructive electrostatic discharge phenomena is discussed along with the time-step size on the simulation of negative resistance structures. >
353647
On Estimating Tight-Link Bandwidth Characteristics over Multi-Hop Paths
In this paper, we explore multi-hop bandwidth estimation assuming arbitrary cross-traffic at each node and develop a new probing method called Envelope that can asymptotically estimate not only the available bandwidth but also the raw capacity of the tight link. Envelope is based on a multi-link recursive extension of unbiased single-hop estimators proposed in the past (e.g., [14]) and a variation of the packet-cartouche technique [6]. Through extensive simulations, we evaluate Envelope in various network settings and cross-traffic conditions and find that it can measure tight-link bandwidth characteristics with accuracy that significantly surpasses that of the existing methods. We also find that Envelope can measure non-tight links in certain path and cross-traffic configurations.
14376041
Feasible region approximation using convex polytopes
A new technique for polytope approximation of the feasible region for a design is presented. This method is computationally less expensive than the simplicial approximation method. Results on several circuits are presented. It is shown that the quality of the polytope approximation is substantially better than an ellipsoidal approximation.<<ETX>>
8305231
Packet-pair bandwidth estimation: stochastic analysis of a single congested node
We examine the problem of estimating the capacity of bottleneck links and available bandwidth of end-to-end paths under non-negligible cross-traffic conditions. We present a simple stochastic analysis of the problem in the context of a single congested node and derive several results that allow the construction of asymptotically-accurate bandwidth estimators. We first develop a generic queuing model of an Internet router and solve the estimation problem assuming renewal cross-traffic at the bottleneck link. Noticing that the renewal assumption on Internet flows is too strong, we investigate an alternative filtering solution that asymptotically converges to the desired values of the bottleneck capacity and available bandwidth under arbitrary (including non-stationary) cross-traffic. This is one of the first methods that simultaneously estimates both types of bandwidth and is provably accurate. We finish the paper by discussing the impossibility of a similar estimator for paths with two or more congested routers.