Results 11  20
of
445
Toward a PsychophysicallyBased Light Reflection Model for Image Synthesis
 Proc. SIGGRAPH
, 2000
"... image synthesis based on experimental studies of surface gloss perception. To develop the model, we've conducted two experiments that explore the relationships between the physical parameters used to describe the reflectance properties of glossy surfaces and the perceptual dimensions of glossy ..."
Abstract

Cited by 79 (15 self)
 Add to MetaCart
image synthesis based on experimental studies of surface gloss perception. To develop the model, we've conducted two experiments that explore the relationships between the physical parameters used to describe the reflectance properties of glossy surfaces and the perceptual dimensions of glossy appearance. In the first experiment we use multidimensional scaling techniques to reveal the dimensionality of gloss perception for simulated painted surfaces. In the second experiment we use magnitude estimation methods to place metrics on these dimensions that relate changes in apparent gloss to variations in surface reflectance properties. We use the results of these experiments to rewrite the parameters of a physicallybased light reflection model in perceptual terms. The result is a new psychophysicallybased light reflection model where the dimensions of the model are perceptually meaningful, and variations along the dimensions are perceptually uniform. We demonstrate that the model can facilitate describing surface gloss in graphics rendering applications. This work represents a new methodology for developing light reflection models for image synthesis.
Graph drawing by stress majorization
 GRAPH DRAWING
, 2004
"... One of the most popular graph drawing methods is based of achieving graphtheoretic target ditsances. This method was used by Kamada and Kawai [15], who formulated it as an energy optimization problem. Their energy is known in the multidimensional scaling (MDS) community as the stress function. In th ..."
Abstract

Cited by 72 (11 self)
 Add to MetaCart
One of the most popular graph drawing methods is based of achieving graphtheoretic target ditsances. This method was used by Kamada and Kawai [15], who formulated it as an energy optimization problem. Their energy is known in the multidimensional scaling (MDS) community as the stress function. In this work, we show how to draw graphs by stress majorization, adapting a technique known in the MDS community for more than two decades. It appears that majorization has advantages over the technique of Kamada and Kawai in running time and stability. We also present a few extensions to the basic energy model which can improve layout quality and computation speed in practice. Majorizationbased optimization is essential to these extensions.
Towards a General Theory of Topological Maps
 Artificial Intelligence
, 2002
"... We present a general theory of topological maps whereby sensory input, topological and local metrical information are combined to define the topological maps explaining such information. Topological maps correspond to the minimal models of an axiomatic theory describing the relationships between ..."
Abstract

Cited by 70 (9 self)
 Add to MetaCart
We present a general theory of topological maps whereby sensory input, topological and local metrical information are combined to define the topological maps explaining such information. Topological maps correspond to the minimal models of an axiomatic theory describing the relationships between the different sources of information explained by a map. We use a circumscriptive theory to specify the minimal models associated with this representation.
GPS free coordinate assignment and routing in wireless sensor networks
 In IEEE INFOCOM
, 2005
"... Abstract — In this paper we consider the problem of constructing a coordinate system in a sensor network where location information is not available. To this purpose we introduce the Virtual Coordinate assignment protocol (VCap) which defines a virtual coordinate system based on hop distances. As co ..."
Abstract

Cited by 63 (0 self)
 Add to MetaCart
Abstract — In this paper we consider the problem of constructing a coordinate system in a sensor network where location information is not available. To this purpose we introduce the Virtual Coordinate assignment protocol (VCap) which defines a virtual coordinate system based on hop distances. As compared to other approaches, VCap is simple and have very little requirements in terms of communication and memory overheads. We compare by simulations the performances of greedy routing using our virtual coordinate system with the one using the physical coordinates. Results show that the virtual coordinate system can be used to efficently support geographic routing. Index Terms — Wireless sensor network, virtual coordinates, hop based greedy routing, performance analysis, simulations I.
Binary Analysis and OptimizationBased Normalization of Gene Expression Data
, 2002
"... Motivation: Most approaches to gene expression analysis use realvalued expression data, produced by highthroughput screening technologies, such as microarrays. Often, some measure of similarity must be computed in order to extract meaningful information from the observed data. The choice of this si ..."
Abstract

Cited by 56 (6 self)
 Add to MetaCart
Motivation: Most approaches to gene expression analysis use realvalued expression data, produced by highthroughput screening technologies, such as microarrays. Often, some measure of similarity must be computed in order to extract meaningful information from the observed data. The choice of this similarity measure frequently has a profound effect on the results of the analysis, yet no standards exist to guide the researcher.
Efficient Computation of IsometryInvariant Distances between Surfaces
"... We present an efficient computational framework for isometryinvariant comparison of smooth surfaces. We formulate the GromovHausdorff distance as a multidimensional scaling (MDS)like continuous optimization problem. In order to construct an efficient optimization scheme, we develop a numerical ..."
Abstract

Cited by 55 (18 self)
 Add to MetaCart
We present an efficient computational framework for isometryinvariant comparison of smooth surfaces. We formulate the GromovHausdorff distance as a multidimensional scaling (MDS)like continuous optimization problem. In order to construct an efficient optimization scheme, we develop a numerical tool for interpolating geodesic distances on a sampled surface from precomputed geodesic distances between the samples. For isometryinvariant comparison of surfaces in the case of partially missing data, we present the partial embedding distance, which is computed using a similar scheme. The main idea is finding a minimumdistortion mapping from one surface to another, while considering only relevant geodesic distances. We discuss numerical implementation issues and present experimental results that demonstrate its accuracy and efficiency.
Knowledge mining with VxInsight: Discovery through interaction
 JOURNAL OF INTELLIGENT INFORMATION SYSTEMS
, 1998
"... The explosive growth in the availability of information is overwhelming traditional information management systems. Although individual pieces of information have become easy to find, the larger context in which they exist has become harder to track. These contextual questions are ideally suited to ..."
Abstract

Cited by 47 (4 self)
 Add to MetaCart
The explosive growth in the availability of information is overwhelming traditional information management systems. Although individual pieces of information have become easy to find, the larger context in which they exist has become harder to track. These contextual questions are ideally suited to visualization since the humrex visual system is remarkably adept at interpreting large quantities of information, and at detecting patterns and anomalies. The challenge is to present the information in a manner that maximally leverages our v/sual skills. This paper discusses a set of properties that such a presentation should have, and describes the design and functionality of Vxlnsight, a visualization tool built to these principles.
Correspondence analysis of genes and tissue types and finding genetic links from microarray data
 Genome Informatics
, 2000
"... In this paper, we propose and use two novel procedures for the analysis of microarray gene expression data. The first is correspondence analysis which visualizes the relationship between genes and tissues as two 2 dimensional graphs, oriented so that distances between genes are preserved, distances ..."
Abstract

Cited by 44 (1 self)
 Add to MetaCart
In this paper, we propose and use two novel procedures for the analysis of microarray gene expression data. The first is correspondence analysis which visualizes the relationship between genes and tissues as two 2 dimensional graphs, oriented so that distances between genes are preserved, distances between tissues are preserved, and so that genes which primarily distinguish certain types of tissue are spatially close to those tissues. For the inference of genetic links, partial correlations rather than correlations are the key issue. A partial correlation between i and j is the relationship between i and j after the effect of surrounding genes has been subtracted out of their pairwise correlation. This leads to the area of graphical modeling. A limitation of the graphical modeling approach is that the correlation matrix of expression profiles between genes is degenerate whenever the number of genes to be analyzed exceeds the number of distinct expression measurements. This can cause considerable problems, as calculation of partial correlations typically uses the inverse of the correlation matrix. To avoid this limitation, we propose two practical multiple regression procedures with variable selection to measure the net, screened, relationship between pairs of genes. Possible biases arising from the analysis of a subset of genes from the genome are examined in the worked examples. It seems that both these approaches are more natural ways of analyzing gene expression data than the currently popular approach of two way clustering.