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.
122813254
Shape Ambiguities in Structure From Motion
This paper examines the fundamental ambiguities and uncertainties inherent in recovering structure from motion. By examining the eigenvectors associated with null or small eigenvalues of the Hessian matrix, we can quantify the exact nature of these ambiguities and predict how they affect the accuracy of the reconstructed shape. Our results for orthographic cameras show that the bas-relief ambiguity is significant even with many images, unless a large amount of rotation is present. Similar results for perspective cameras suggest that three or more frames and a large amount of rotation are required for metrically accurate reconstruction.
17348246
Lighting interpolation by shadow morphing using intrinsic lumigraphs
Densely-sampled image representations such as the light field or lumigraph have been effective in enabling photorealistic image synthesis. Unfortunately, lighting interpolation with such representations has not been shown to be possible without the use of accurate 3D geometry and surface reflectance properties. In this paper we propose an approach to image-based lighting interpolation that is based on estimates of geometry and shading from relatively few images. We decompose captured light fields at different lighting conditions into intrinsic images (reflectance and illumination images), and estimate view-dependent scene geometries using multi-view stereo. We call the resulting representation an intrinsic lumigraph. In the same way that the lumigraph uses geometry to permit more accurate view interpolation, the intrinsic lumigraph uses both geometry and intrinsic images to allow high-quality interpolation at different views and lighting conditions. Joint use of geometry and intrinsic images is effective in the computation of shadow masks for shadow prediction at new lighting conditions. We illustrate our approach with images of real scenes.
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.
26233543
Appearance-Based Structure from Motion Using Linear Classes of 3-D Models
In this paper, we address the problem of recovering 3-D models from sequences of partly calibrated images with unknown correspondence. To that end, we integrate tracking, structure from motion with geometric constraints (specifically in the form of linear class models) in a single framework. The key to making the proposed approach work is the use of appearance-based model matching and refinement which updates the estimated correspondences on each iteration of the algorithm. Another key feature is the matching of a 3-D model directly with the input images without the conventional 2-step approach of stereo data recovery and 3-D model fitting. Initialization of the linear class model to one of the input images (the reference image) is currently partly manual.This synthesis and refine approach, or appearance-based constrained structure from motion (AbCSfm), is especially useful in recovering shapes of objects whose general structureis known but which may have little discernable texture in significant parts of their surfaces. We applied the proposed approach to 3-D face modeling from multiple images to create new 3-D faces for DECface, a synthetic talking head developed at Cambridge Research Laboratory, Digital Equipment Corporation. The DECface model comprises a collection of 3-D triangular and rectangular facets, with nodes as vertices. In recovering the DECface model, we assume that the sequence of images is taken with a camera with unknown focal length and pose. The geometric constraints used are of the form of linear combination of prototypes of 3-D faces of real people. Results of this approach show its good convergence properties and its robustness against cluttered backgrounds.
41028764
Large environment rendering using plenoptic primitives
One of the most difficult tasks in computer graphics is to enable virtual walkthroughs in very large and complicated environments that are photorealistic, seamless, and in real time. Current image-based rendering techniques, while capable of photorealism and interactive speeds, have failed in practice to extend to visualizations of such environments. We demonstrate an approach that defines a virtual walkthrough experience using plenoptic primitives (PPs). A PP can be any type of local visual experience: 360/spl deg/ static panorama, panoramic video (PV), lumigraph/light field representation, or concentric mosaics (CMs). By combining them judiciously, user experience can be authored with significantly reduced effort while maintaining high-quality user experience. We illustrate our technique on synthetic and real environments using PVs and CMs and show how the problem of achieving smooth transitions among PVs and CMs can be solved by using position-dependent local geometries.
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. >
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.
17977437
Technology independent arbitrary device extractor
This paper presents the technology independent arbitrary device specification language and device extraction algorithm used in our layout extractor iLEX. Device models specified in the device specification language are converted to graphs, and subgraph isomorphism is used to extract device instances in given layouts. Finally, experimental data are provided to show the capability of our device extraction algorithms.
16869035
An approach to virtual allocation in storage systems
This article presents virtual allocation, a scheme for flexible storage allocation. Virtual allocation separates storage allocation from the file system. It employs an allocate-on-write strategy which lets applications fit into the actual usage of storage space, without regard to the configured file system size. This improves flexibility by allowing storage space to be shared across different file systems. This article presents the design of virtual allocation and its evaluation through benchmarks. To illustrate our approach, we implemented a prototype system on PCs running Linux. We present the results from the prototype implementation and its evaluation.
205396452
Video dejittering by bake and shake
Video jittering occurs when the horizontal lines of video image frames are randomly displaced due to the corruption of synchronization signals or electromagnetic interference during video transmission. Inspired by the recent Bayesian/variational dejittering model of Shen (SIAM J. Appl. Math., vol. 64, pp. 1691-1708, 2004), in the current paper we propose a novel dejittering approach nicknamed 'bake-and-shake.' The bake step is to apply Perona-Malik type nonlinear diffusions to 'melt away' or heat up the jittered video frames, based upon which the shake step is able to optimally estimate the individual line jitters and renormalize the jittered images. Numerical implementation of the bake-and-shake algorithm as well as several computational results are presented.