16309802
Virtual Navigation of Complex Scenes using Clusters of Cylindrical Panoramic Images
The traditional approach of generating novel virtual views of an object or a scene is to render the appropriate 3-D model. Higher realism can be achieved by texture-mapping object surfaces or simulating surface reflectance properties. The alternative is to render directly from the original images; this approach, which is based on pixel interpolation or reprojection, is called image-based rendering. In this technical report, we describe a technique that enables virtual navigation within a complex environment using an image-based rendering technique. In particular, we make use of clusters of cylindrical panoramic images. Each cluster of panoramic images allows the user to smoothly navigate within a particular area, say within a single room. Having a collection of such interconnected clusters would enable the user to seamlessly navigate within a complex environment, such as an entire floor of a building, with each cluster representing a room. To achieve this goal, we examine a few techniques for image-based rendering using a cluster of cylindrical panoramic images to synthesize views from virtual viewpoints. We also describe our method for enabling smooth transition between clusters. 1Computer Science Dept., Duke University, Durham, NC 27708 c Digital Equipment Corporation, 1997 This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of the Cambridge Research Laboratory of Digital Equipment Corporation in Cambridge, Massachusetts; an acknowledgment of the authors and individual contributors to the work; and all applicable portions of the copyright notice. Copying, reproducing, or republishing for any other purpose shall require a license with payment of fee to the Cambridge Research Laboratory. All rights reserved. CRL Technical reports are available on the CRL’s web page at http://www.crl.research.digital.com. Digital Equipment Corporation Cambridge Research Laboratory One Kendall Square, Building 700 Cambridge, Massachusetts 02139
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.
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.
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.
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.
29231099
A new circuit optimization technique for high performance CMOS circuits
A novel transistor sizing technique with a concise problem formulation and rigorous optimization scheme is described. A circuit optimization technique for high-performance CMOS circuits is presented for proper balance of chip speed and area. The timing specification is accommodated as a design constraint, and reliability issues in the charge sharing and noise margin, which have been neglected in previous optimization tools, are also embedded into the design constraints. The optimization scheme used in this approach does not require derivatives, and therefore, can be used for a broad class of continuous cost functions. Special attention is given to the most effective use of silicon area based on the sensitivity of the delay time with respect to the transistor size. Excessively large transistor sizes are avoided by using the resource redistribution scheme. This timing allocation scheme allows the computation time to be linearly proportional to the number of gates. >
12383139
Thermal failure simulation for electrical overstress in semiconductor devices
Electrical overstress (EOS) and electrostatic discharge (ESD) constitute one of the most dominant threats to integrated circuits (ICs). A nonlinear 2-D/1-D thermal simulator suitable for ESD/EOS thermal failure modeling in ICs is reported. The unboundedness of the thermal problem is addressed by a special set of boundary conditions, making the thermal simulation task computationally efficient. Simulated power-to-failure vs. time-to-failure relationships (power profiles) for various combinations of major IC structural parameters are presented and compared with experimental data.<<ETX>>
16084555
2.4GHz ZigBee radio architecture with fast frequency offset cancellation loop
This paper describes a radio architecture with fast analog frequency offset cancellation loop which is based on a SigmaDelta fractional-N frequency synthesizer and a frequency offset detector. The offset detector is composed of a frequency/phase detector (PFD) and a new non-uniform resolution time-to-digital converter (TDC). By adopting the weighted delay-length for the TDC, only 60-DFFs are used to generate digitized timing difference of 250ns with a minimum resolution of 1ns. For the 2.4GHz ZigBee transceiver with 4MHz IF, designed for 0.18mum CMOS process, the frequency offset cancellation time takes about 30mus under the PLL loop-bandwidth of 100 kHz
5129503
Detailed layer assignment for MCM routing
A new routing environment model, called the k-MCM model, is developed to take into account the unique features of a multilayer MCM, such as the availability of “segmented vias” , and the presence of two “active” or terminal-bearing layers. A detailed layer assignment problem is formulated on the k-MCM model. A fast heuristic algorithm for the layer assignment problem is proposed. and experimental results on twelve test examples with net counts up to 842 are presented.
5192887
Convexity-based algorithms for design centering
A new technique for design centering and polytope approximation of the feasible region for a design are presented. In the first phase, the feasible region is approximated by a convex polytope, using a method based on a theorem on convex sets. As a natural consequence of this approach, a good approximation to the design center is obtained. In the next phase, the exact design center is estimated using one of two techniques that we present in this paper. The first inscribes the largest Hessian ellipsoid, which is known to be a good approximation to the shape of the polytope, within the polytope. This represents an improvement over previous methods, such as simplicial approximation, where a hypersphere or a crudely estimated ellipsoid is inscribed within the approximating polytope. However, when the probability density functions of the design parameters are known, the design center does not necessarily correspond to the center of the largest inscribed ellipsoid. Hence, a second technique is developed that incorporates the probability distributions of the parameters, under the assumption that their variation is modeled by Gaussian probability distributions. The problem is formulated as a convex programming problem and an efficient algorithm is used to calculate the design center, using fast and efficient Monte Carlo methods to estimate the yield gradient. An example is provided to illustrate how ellipsoid-based methods fail to incorporate the probability density functions and is solved using the convex programming-based algorithm. >