8653140
Multibaseline stereo in the presence of specular reflections
We address the problem of accurate depth estimation using multibaseline stereo in the presence of specular reflections. Specular reflections can cause the intensity and color of corresponding points to change dramatically according to different viewpoints, thus producing severe matching errors for various stereo algorithms. In this paper we propose a new method to deal with this problem by treating specular reflections as occlusions. Our idea is to first detect specular pixels by computing the uncertainty of depth estimates. Then we combine the use of flexible windows and an adaptively selected subset of images to avoid these specular areas in all the multibaseline stereo images. Even though specularities may exist in the reference image, accurate depth is nevertheless estimated for all pixels. Experiments show that our consideration of specular reflections leads to improved stereo results.
14760859
Multiple-cue illumination estimation in textured scenes
In this paper, we present a method that integrates cues from shading, shadow and specular reflections for estimating directional illumination in a textured scene. Texture poses a problem for lighting estimation, since texture edges can be mistaken for changes in illumination condition, and unknown variations in albedo make reflectance model fitting impractical. Unlike previous works which all assume known or uniform reflectance, our method can deal with the effects of textures by capitalizing on physical consistencies that exist among the lighting cues. Since scene textures do not exhibit such coherence, we use this property to minimize the influence of texture on illumination direction estimation. For the recovered light source directions, a technique for estimating their intensities in the presence of texture is also proposed.
2702895
Single-image reflectance estimation for relighting by iterative soft grouping
Reflectance values for image-based relighting are often estimated from grouped pixels with similar reflectance, but such groupings are difficult to compute with certainty for sparse image data. To address this problem, we propose an iterative method that aggregates BRDF data in a single image with known geometry and lighting by soft grouping, where pixels contribute to one another's estimate according to their degree of reflectance similarity. Estimation of specular reflectance is further improved by albedo-independent soft grouping of pixels based on shape continuity. With recovered reflectances, we demonstrate realistic relighting for synthetic and real scenes, including surfaces with spatially-varying reflectance.
24872800
Face Recognition using Patch-based Spin Images
This paper explores how spin images can be constructed using shape-from-shading information and used for the purposes of face recognition. We commence by extracting needle-maps from gray-scale images of faces, using a mean needle-map to enforce the correct pattern official convexity and concavity. Spin images (Johnson and Hebert, 1999) are estimated from the needle maps using local spherical geometry to approximate the facial surface. Our representation is based on the spin image histograms for an arrangement of image patches. We demonstrate how this representation can be used to perform face recognition across different subjects and illumination conditions. Experiments show the method to be reliable and accurate
8996068
A mobile sensor network using autonomously controlled animals
Recent research has demonstrated that it is possible to use wireless communication to deliver brain stimulation to guide the movements of rats through a variety of terrains by stimulating multiple brain regions to produce stimulus cues for various commanded movements. The rats can be controlled not only while in direct line of sight of a human controller, but also by teleoperation, using signals transmitted from a wireless video camera mounted on the animal's backpack. Remotely guided rats or other animals are ideal for search and rescue operations because they are highly adept at negotiating difficult 3D terrain, in both light and dark. The animals autonomously choose their own methods for traversing particular obstacles. Primarily for these reasons, they can be more effective than mechanical robots in search and rescue applications. They can also be trained to detect and home in on specific sensory targets, allowing them to be used as biosensors. To meet these challenges, a cluster of interrelated research studies, including network topology design, routing algorithms, media access control techniques, radio resource management, radio propagation modeling, and mobility modeling are comprised. In this paper, the authors have designed and implemented the hardware of backpacks and set up a simple wireless ad hoc network by using static routing.
1475500
Efficient XML Data Management: An Analysis
With XML rapidly gaining popularity as the standard for data exchange on the World Wide Web, a variety of XML management systems (XMLMS) are becoming available. The choice of an XMLMS is made difficult by the significant difference in the expressive power of the queries and the performance shown by these XMLMS. Most XMLMS are legacy systems (mostly relational) extended to load, query, and publish data in XML format. A few are native XMLMS and capture all the characteristics of XML data representation. This paper looks at expressive power and efficiency of various XMLMS. The performance analysis relies on the testbed provided by XOO7, a benchmark derived from OO7 to capture both data and document characteristics of XML. We present efficiency results for two native XMLMS, an XML-enabled semistructured data management system and an XML-enabled RDBMS, which emphasize the need for a delicate balance between the data-centric and document-centric aspects of XML query processing.
7384853
Consistent line clusters for building recognition in CBIR
This paper introduces a new mid-level feature, the consistent line cluster for use in content-based image retrieval. The color, orientation, and spatial features of line segments are exploited to group them into line clusters. The interrelationships among different clusters and the intra relationships within single clusters are used to recognize and roughly locate buildings in photographic images. Experiments are performed on a database of color images of outdoor scenes.
16207650
Term Disambiguation in Natural Language Query for XML
Converting a natural language query sentence into a formal database query is a major challenge. We have constructed NaLIX, a natural language interface for querying XML data. Through our experience with NaLIX, we find that failures in natural language query understanding can often be dealt with as ambiguities in term meanings. These failures are typically the result of either the user's poor knowledge of the database schema or the system's lack of linguistic coverage. With automatic term expansion techniques and appropriate interactive feedback, we are able to resolve these ambiguities. In this paper, we describe our approach and present results demonstrating its effectiveness.