unity scene algorithm
4327732
A computer algorithm for reconstructing a scene from two projections
A simple algorithm for computing the three dimensional structure of a scene from a correlated pair of perspective projections is described here, when the spatial relationship between the two projections is unknown. This problem is relevant not only to photographic surveying1 but also to binocular vision2, where the non visual information available to the observer about the orientation and focal length of each eye is much less accurate than the optical information supplied by the retinal images themselves. The problem also arises in monocular perception of motion3, where the two projections represent views which are separated in time as well as space. As Marr and Poggio4 have noted, the fusing of two images to produce a three dimensional percept involves two distinct processes: the establishment of a 1:1 correspondence between image points in the two views the 'correspondence problem' and the use of the associated disparities for determining the distances of visible elements in the scene. I shall assume that the correspondence problem has been solved; the problem of reconstructing the scene then reduces to that of finding the relative orientation of the two viewpoints.
Nature
Hugh Christopher Longuet-Higgins
142854058
Consilience: The Unity of Knowledge
In this groundbreaking new book, one of the world's greatest living scientists argues for the fundamental unity of all knowledge and the need to search for what he calls consilience, the composition of the principles governing every branch of learning. Edward O Wilson, the pioneer of sociobiology and biodiversity, once again breaks out of the conventions of current thinking. He shows how our explosive rise in intellectual mastery of the truths of our universe has its roots in the ancient Greek concept of an intrinsic orderliness that governs our cosmos. It is a vision that found its apogee in the Age of Enlightenment, then gradually was lost in the increasing fragmentation and specialisation of knowledge in the last two centuries. Professor Wilson shows why the goals of the original Enlightenment are surging back to life, why they are reappearing on the very frontiers of science and human scholarship, and how they are beginning to sketch themselves as the blueprint of our world.
Edward O Wilson
6575336
Multi level Partition of Unity Implicits
1. Briefly summarize the paper's contributions. Does it address a new problem? Does it present a new approach? Does it show new types of results? [AS] This paper presents a new approach to construct surface models from extremely large point sets using piecewise quadratic functions that capture the local shape of the surface, and then blending them together using multi level partitions of unity as weighting functions. This is the first method to use partitions of the point set into regions to fit implicit functions to, as opposed to function fitting at every point, in previous methods. [DS] The paper presents a surface representation using multi level partition of unity (MPU) implicit surfaces. Presents an approach with the 3 key concepts: 1. Piecewise quadratic functions used as local shape estimates for the surface. 2. Weighing functions (partition of unity) to blend the local shape functions. 3. Octree subdivision that adapts based on shape complexity. This approach is adaptive based on the desired accuracy. The use of implicit functions provide data repairing capabilities for scattered data and an easy way to perform implicit modeling operations. [FP] This paper proposes a method to implicitly define a surface as the zero level of a distance function. The space is partitioned in octree cells and a shape function is fitted to each cell. In contrast to previous approaches (such as Hoppe 92) the distance to the surface (i.e. the implicit function evaluation) is not computed respect to a single element of the space partition (in this case, an octree cell) but is a weighted sum. Due to the partition of unity approach and the use of smooth weighting function, the distance function changes smoothly along the 3D space. [JD] [LF] The paper introduces the partition of unity approach for approximation of the signed distance function of a set of scattered points with normals. The method breaks up the point set using octree subdivision (can handle complex topology) It then uses piecewise quadratic function as local approximations of the surface. These local approximations are blended together using smooth, local weights (can represent sharp features) [MK] This paper proposes an efficient, octree based, algorithm for reconstructing surfaces from oriented point samples. The approach falls somewhere between global implicit methods and MLS approaches, as the approach partitions space, computes a local implicit surface around each partition, and then glues these together using a partition
Yutaka Ohtake Alexander G Belyaev Marc Alexa Greg Turk Hans-Peter Seidel
8430733
Scene completion using millions of photographs
What can you do with a million images? In this paper, we present a new image completion algorithm powered by a huge database of photographs gathered from the Web. The algorithm patches up holes in images by finding similar image regions in the database that are not only seamless, but also semantically valid. Our chief insight is that while the space of images is effectively infinite, the space of semantically differentiable scenes is actually not that large. For many image completion tasks, we are able to find similar scenes which contain image fragments that will convincingly complete the image. Our algorithm is entirely data driven, requiring no annotations or labeling by the user. Unlike existing image completion methods, our algorithm can generate a diverse set of image completions and we allow users to select among them. We demonstrate the superiority of our algorithm over existing image completion approaches.
Commun. ACM
James Hays Alexei A Efros
220996717
Auditory Scene Analysis
A mixture of sounds, though distinct in the environment, arrives in the form of a single pressure wave at each ear. From it, listeners must extract the signals coming from individual sources of sound, a process called auditory scene analysis (ASA) ASA first characterizes the incoming waveform by its frequency components and other features, then creates subsets (auditory streams) that extend over time, each representing a single environmental sound source. ASA exploits regularities in the signal to determine how to parse it. ASA is present at birth in humans and has been found in other animals.
Albert S Bregman
123450931
Adaptive speckle filters and scene heterogeneity
The presence of speckle in radar images makes the radiometric and textural aspects less efficient for class discrimination. Many adaptive filters have been developed for speckle reduction, the most well known of which are analyzed. It is shown that they are based on a test related to the local coefficient of variation of the observed image, which describes the scene heterogeneity. Some practical criteria are introduced to modify the filters in order to make them more efficient. The filters are tested on a simulated synthetic aperture radar (SAR) image and an SAR 580 image. As was expected, the new filters perform better, i.e. they average the homogeneous areas better and preserve texture information, edges, linear features, and point target responses better at the same time. Moreover, they can be adapted to features other than the coefficient of variation to reduce the speckle while preserving the corresponding information.
Armand Lopes Ridha Touzi Edmond Nezry
195592487
The Auditory Scene. (Book Reviews: Auditory Scene Analysis. The Perceptual Organization of Sound.
Auditory Scene Analysis addresses the problem of hearing complex auditory environments, using a series of creative analogies to describe the process required of the human auditory system as it analyzes mixtures of sounds to recover descriptions of individual sounds. In a unified and comprehensive way, Bregman establishes a theoretical framework that integrates his findings with an unusually wide range of previous research in psychoacoustics, speech perception, music theory and composition, and computer modeling.
Albert S Bregman
18603445
Scene Labeling by Relaxation Operations
Given a set of objects in a scene whose identifications are ambiguous, it is often possible to use relationships among the objects to reduce or eliminate the ambiguity. A striking example of this approach was given by Waltz [13] This paper formulates the ambiguity reduction process in terms of iterated parallel operations (i.e. relaxation operations) performed on an array of (object, identification) data. Several different models of the process are developed, convergence properties of these models are established, and simple examples are given.
IEEE Transactions on Systems, Man, and Cybernetics
Azriel Rosenfeld Robert A Hummel Steven W Zucker
7276309
Computational auditory scene analysis
Abstract Although the ability of human listeners to perceptually segregate concurrent sounds is well documented in the literature, there have been few attempts to exploit this research in the design of computational systems for sound source segregation. In this paper, we present a segregation system that is consistent with psychological and physiological findings. The system is able to segregate speech from a variety of intrusive sounds, including other speech, with some success. The segregation system consists of four stages. Firstly, the auditory periphery is modelled by a bank of bandpass filters and a simulation of neuromechanical transduction by inner hair cells. In the second stage of the system, periodicities, frequency transitions, onsets and offsets in auditory nerve firing patterns are made explicit by separate auditory representations. The representations, auditory maps are based on the known topographical organization of the higher auditory pathways. Information from the auditory maps is used to construct a symbolic description of the auditory scene. Specifically, the acoustic input is characterized as a collection of time frequency elements, each of which describes the movement of a spectral peak in time and frequency. In the final stage of the system, a search strategy is employed which groups elements according to the similarity of their fundamental frequencies, onset times and offset times. Following the search, a waveform can be resynthesized from a group of elements so that segregation performance may be assessed by informal listening tests. The system has been evaluated using a database of voiced speech mixed with a variety of intrusive noises such as music, "office" noise and other speech. A technique for quantitative evaluation of the system is described, in which the signal to noise ratio (SNR) is compared before and after the segregation process. After segregation, an increase in SNR is obtained for each noise condition. Additionally, the performance of our system is significantly better than that of the frame based segregation scheme described by Meddis and Hewitt (1992)
Comput. Speech Lang.
Guy J Brown Martin Cooke
6740010
The Dynamic Representation of Scenes
One of the more powerful impressions created by vision is that of a coherent, richly detailed world where everything is present simultaneously. Indeed, this impression is so compelling that we tend to ascribe these properties not only to the external world, but to our internal representations as well. But results from several recent experiments argue against this latter ascription. For example, changes in images of real world scenes often go unnoticed when made during a saccade, flicker, blink, or movie cut. This change blindness provides strong evidence against the idea that our brains contain a picture like representation of the scene that is everywhere detailed and coherent. How then do we represent a scene? It is argued here that focused attention provides spatiotemporal coherence for the stable representation of one object at a time. It is then argued that the allocation of attention can be coordinated to create a virtual representation. In such a scheme, a stable object representation is formed whenever needed, making it appear to higher levels as if all objects in the scene are represented in detail simultaneously.
Ronald A Rensink