1332259
On the Motion and Appearance of Specularities in Image Sequences
Real scenes are full of specularities (highlights and reflections), and yet most vision algorithms ignore them. In order to capture the appearance of realistic scenes, we need to model specularities as separate layers. In this paper, we study the behavior of specularities in static scenes as the camera moves, and describe their dependence on varying surface geometry, orientation, and scene point and camera locations. For a rectilinear camera motion with constant velocity, we study how the specular motion deviates from a straight trajectory (disparity deviation) and how much it violates the epipolar constraint (epipolar deviation). Surprisingly, for surfaces that are convex or not highly undulating, these deviations are usually quite small. We also study the appearance of specularities, i.e., how they interact with the body reflection, and with the usual occlusion ordering constraints applicable to diffuse opaque layers. We present a taxonomy of specularities based on their photometric properties as a guide for designing separation techniques. Finally, we propose a technique to extract specularities as a separate layer, and demonstrate it using an image sequence of a complex scene.
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.
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.
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.
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.
14227015
Towards an Efficient Semantic Prefetching for Location Based Services
Location-Based Services(LBSs) in a wireless location-aware network are public and personal services intended to be available for users. It is important to support Location Dependent Data(LDD) that users want to get to their moving location properly. If we get many LDD in a local device, the communication cost increased by frequent connections can remarkably reduce. General prefetching scheme make it possible to send data to mobile clients in advance. But, after analyzing queries fixed to users’ interests in current location, it is difficult to support proper data in LBSs. Therefore, we propose a Semantic Prefetching scheme to efficiently prefetch LDD and semantic description through servers with large scale data. Also, with our semantic prefetching scheme for LDD in LBSs, we propose a new cache management scheme to manage data needed by mobile users. A performance study shows efficiency of these schemes when compared to traditional semantic cache scheme.
42528571
Modeling of nMOS transistors for simulation of hot-carrier-induced device and circuit degradation
The authors present an accurate one-dimensional device model for the simulation of nMOS transistors with hot-carrier-induced oxide damage. The model uses a realistic charge density distribution profile to account for the localization of the oxide-interface charge near the drain. Model simulation results obtained for nMOS transistors with hot-carrier-induced oxide damage demonstrate good agreement with the experimental data. The amount and the location of the hot-carrier-induced oxide damage are simulated by using only a few parameters, which simplifies the implementation of the model in a reliability simulation environment. The proposed model has been implemented in the iSMILE circuit simulator, and the capabilities of the model have been explored by various circuit simulation examples. The damaged-MOSFET model presented offers a simple and accurate approach for simulating the circuit behavior after hot-carrier damage. >
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.
40491047
Domino logic synthesis based on implication graph
In this paper, we present a new approach to the problem of inverter elimination in domino logic synthesis. A small piece of static CMOS logic is introduced to the circuit to avoid significant area penalty resulting from duplication. To maximize the domino logic part and to minimize the static CMOS logic part, a generalized automatic test pattern generation (ATPG)-based logic transformation is proposed to eliminate or relocate a target inverter. Based on the new concept of dominating set of mandatory assignment (DSMA) and the corresponding implication graph, we propose algorithms to identify a minimum candidate set for a target inverter. Experimental results show that logic transformation based on the implication graph can reduce transistor counts by 25% on average, while the delay increases less than 3%.
53239407
Logic Transformation for Low Power Synthesis
In this paper we present a new approach to the problem of local logic transformation for reduction of power dissipation in logic circuits. Based on the finite-state input transition (FIT) power dissipation model, we introduce a cost function which accounts for the effects of input capacitance, input slew rate, internal parasitic capacitance of logic gates, interconnect capacitance, as well as switching power. Our approach provides an efficient way of estimating estimating the global effect of local logic transformations in logic circuits. In our approach, the FIT model for the transitive fanout cells of a locally transformed subcircuit can be reused to measure the global power dissipation by varying the input probabilities of the transitive fanout cells. Local logic transformation is carried our based on compatible sets of permissible functions (CSPF). Experimental results show that local logic transformation based on CSPF using our cost function can reduce power consumption by about 36% on average without increase in the worst-case circuit delay.