Allen Hanson

Allen Hanson
University of Massachusetts Amherst | UMass Amherst · School of Computer Science

Ph.D.

About

268
Publications
24,634
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7,261
Citations
Additional affiliations
September 1980 - June 2008
University of Massachusetts Amherst
Position
  • Professor (Full)
January 1977 - December 2009
University of Massachusetts Amherst

Publications

Publications (268)
Conference Paper
Full-text available
In moving camera videos, motion segmentation is com- monly performed using the image plane motion of pixels, or optical flow. However, objects that are at different depths from the camera can exhibit different optical flows even if they share the same real-world motion. This can cause a depth-dependent segmentation of the scene. Our goal is to deve...
Article
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In its early implementations, background modeling was a process of building a model for the background of a video with a stationary camera, and identifying pixels that did not conform well to this model. The pixels that were not well-described by the background model were assumed to be moving objects. Many systems today maintain models for the fore...
Article
Smart environments are being developed to support older adults aging in place. However, the design contributions of the older users have not been explicated. The purpose of this review of literature was to determine how older adults' ideas are being incorporated into the design of smart environments. Twenty-one research articles, incorporating olde...
Article
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Joint alignment of a collection of functions is the process of independently transforming the functions so that they appear more similar to each other. Typically, such unsupervised alignment algorithms fail when presented with complex data sets arising from multiple modalities or make restrictive assumptions about the form of the functions or trans...
Article
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In many algorithms for background modeling, a distribution over feature values is modeled at each pixel. These models, however, do not account for the dependencies that may exist among nearby pixels. The joint domain-range kernel density estimate (KDE) model by Sheikh and Shah [7], which is not a pixel-wise model, represents the background and fore...
Conference Paper
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Recent work on background subtraction has shown developments on two major fronts. In one, there has been increasing sophistication of probabilistic models, from mixtures of Gaussians at each pixel [7], to kernel density estimates at each pixel [1], and more recently to joint domainrange density estimates that incorporate spatial information [6]. An...
Article
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We present a set of algorithms that recovers detailed building surface structures from multiple images taken under normal urban conditions, where severe occlusions and lighting variations occur and are difficult to be modeled effectively. An iterative weighted-average algorithm is designed to recover high-quality consensus texture of the wall facad...
Conference Paper
In this paper, a multi-agent search scheme is presented that supports the recognition of activities and, thus, learning methods for cooperative human-robot interaction. In our approach, stochastic models of human search activity are used to estimate state for HRI. The robot updates a Probabilistic Distribution Function of the target object using th...
Article
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This paper describes the design and preliminary imple-mentation of two distributed smart camera applications: a fall detector and an object finder. These functions are part of a novel suite of applications being developed to address "aging in place" health care technologies. Our approach to these applications is unique in that they are based heavil...
Article
In this paper, we present a hierarchical smart resource coordination and reconfiguration framework for distributed systems. We view the coordination problem as one of context aware resource reconfiguration. The fundamental unit in this hierarchy is a Fault Containment Unit (FCU) that provides run-time fault-tolerance by deciding on the best alterna...
Conference Paper
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In this paper we present the design of a decentralized vision-based object search system that can be used for elder care in a smart environment. In our approach, each autonomous search agent maintains separate estimates of the probability density function (PDF) of the object location and makes independent decisions about its search process. Asynchr...
Article
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kaia portualdea z/g_20110 Pasaia (Gipuzkoa)_Spain, xirigoien@azti.es 1. ABSTRACT Digital images of suspended particles in aquatic systems can reveal abundances, size spectra, and biomass distributions of planktonic organisms and non-living particles. Modern imaging systems are capable of recording the contents of defined volumes of water at high ra...
Article
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Scene text recognition (STR) is the recognition of text anywhere in the environment, such as signs and storefronts. Relative to document recognition, it is challenging because of font variability, minimal language context, and uncontrolled conditions. Much information available to solve this problem is frequently ignored or used sequentially. Simil...
Conference Paper
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This paper describes our experiences with the first partial deployment of Presentations Automatically Organized from Lectures (PAOL), a lecture recording system developed and tested at the University of Massachusetts Amherst. PAOL automatically records all information presented during lectures using any combination of computer, whiteboard, and over...
Article
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Object detection and recognition systems, such as face detectors and face recognizers, are often trained separately and operated in a feed-forward fashion. Selecting a small number of features for these tasks is important to prevent over-fitting and reduce computation. However, when a sys- tem has such related or sequential tasks, selecting feature...
Conference Paper
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We present a semi-Markov model for recognizing scene text that integrates character and word segmentation with recognition. Using wavelet features, it requires only approximate location of the text baseline and font size; no binarization or prior word segmentation is necessary. Our system is aided by a lexicon, yet it also allows non-lexicon words....
Conference Paper
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We describe whiteboard content capture system from Presentations Automatically Organized from Lectures (PAOL) that captures content within the setting of a class- room environment. The system acquires a sequence of im- ages from high-resolution, fixed view cameras and extracts a series of content-rich key frames. The key frames are de- rived by ana...
Conference Paper
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For more than a decade, the RIPPLES group at the University of Massachusetts Amherst has developed and deployed content delivery systems to support on-campus and distance education. This has been an effective but expensive approach because of its dependence on content captured by human operators and substantial production effort. Presentations Auto...
Conference Paper
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This paper describes a system designed to automatically capture classroom events as videos and images. This content is delivered in several ways, most commonly as indexed multimedia presentations but also in real time as notes of classroom events. This content creation system identifies when significant events occur, e.g., material presented by com...
Conference Paper
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This paper presents the design and implementation of a dual-camera sensor network that can be used as a memory assistant tool for assisted living. Our system performs energy-efficient object detection and recognition of commonly misplaced objects. The novelty in our approach is the ability to tradeoff between recognition accuracy and computational...
Article
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We describe a methodology for creating new technologies for assisted living in residential environments. The number of eldercare clients is expected to grow dramatically over the next decade as the baby boom generation approaches 65 years of age. The UMass/Smith ASSIST framework aims to alleviate the strain on centralized medical providers and comm...
Conference Paper
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Using a lexicon can often improve character recognition under challenging conditions, such as poor image quality or unusual fonts. We propose a flexible probabilistic model for character recognition that integrates local language properties, such as bigrams, with lexical decision, having open and closed vocabulary modes that operate simultaneously....
Article
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When Victor Hensen deployed the first true plankton1 net in 1887, he and his colleagues were attempting to answer three fundamental questions: What planktonic organisms are present in the ocean? How many of each type are present? How does the plankton’s composition change over time? Although answering these questions has remained a central goal of...
Article
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We describe an automatic classroom capture system that detects and records significant (stable) points in lectures by sampling and analyzing a sequence of screen capture frames from a PC used for presentations, application demonstrations, etc. The system uses visual inspection techniques to scan the screen capture stream to identify points to store...
Conference Paper
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This paper presents the design, implementation and evalua- tion of a distributed network of smart cameras whose func- tion is to detect and localize falls, an important application in elderly living environments. A network of overlapping smart cameras uses a decentralized procedure for comput- ing inter-image homographies that allows the location o...
Conference Paper
Full-text available
We describe an automatic classroom capture system that detects and records significant (stable) points in lec- tures by sampling and analyzing a sequence of screen cap- ture frames from a PC used for presentations, application demonstrations,etc. The system uses visualinspection tech- niques to scan the screen capture stream to identify points to s...
Article
In this paper we address the problem of fusing images from many video cameras or a moving video camera. The captured images have obvious motion parallax, but they will be aligned and integrated into a few mosaics with a large field-of-view (FOV) that preserve 3D information. We have developed a compact geometric representation that can re-organize...
Article
A wide variety of data sets produced by individual investigators are now synthesized to address ecological questions that span a range of spatial and temporal scales. It is important to facilitate such syntheses so that "consumers" of data sets can be confident that both input data sets and synthetic products are reliable. Necessary documentation t...
Article
This paper presents a unified approach to automatically build dynamic and multi-resolution 360° panoramic (DMP) representations from image sequences captured by hand-held cameras mainly undertaking rotation and zooming for natural scenes with moving targets. A simple (yet stable) rigid motion model and a closed-loop-based mosaicing algorithm are pr...
Conference Paper
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In robot and sensor networks, one of the key challenges is to decide when and where to deploy sensory resources to gather information of optimal value. The problem is essentially one of planning, scheduling and controlling the sensors in the network to acquire data from an environment that is constantly varying. The dynamic nature of the problem pr...
Article
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Environmental monitoring applications require seamless registration of optical data into large area mosaics that are geographically referenced to the world frame. Using frame-by-frame image registration alone, we can obtain seamless mosaics, but it will not exhibit geographical accuracy due to frame-to-frame error accumulation. On the other hand, t...
Conference Paper
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Our world is populated with visual information that a sighted person makes use of daily. Unfortunately, the visually impaired are deprived from such information, which limits their mobility in unconstrained environments. To help alleviate this we are developing a wearable system [1, 19] that is capable of detecting and recognizing signs in natural...
Article
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Visually impaired individuals are unable to utilize the significant amount of information in signs. VIDI is a system for detecting and recognizing signs in the environment and voice synthesizing their contents. The wide variety of signs and unconstrained imaging conditions make the problem challenging. We detect signs using local color and texture...
Conference Paper
Pedestrian detection is a challenging vision task, especially applied to the automotive field where the background changes as the vehicle moves. This paper presents an extensive study upon human body models and the techniques suitable for being used ...
Article
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We propose a classification technique for face expression recognition using AdaBoost that learns by selecting the relevant global and local appearance features with the most discriminating information. Selectivity reduces the dimensionality of the feature space that in turn results in significant speed up during online classification. We compare ou...
Conference Paper
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Earth's oceans are a soup of living micro-organisms known as plankton. As the foundation of the food chain for marine life, plankton are also an integral component of the global carbon cycle which regulates the planet's tem- perature. In this paper, we present a technique for auto- matic identification of plankton using a variety of features and cl...
Conference Paper
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Sighted individuals draw a significant amount of information from signs but this information is denied to the visually impaired. VIDI is an evolving system for detecting and recognizing signs in the environment and voice synthesizing their textual contents. The wide variety of signs commonly encountered and the uncontrolled nature of the real world...
Conference Paper
Full-text available
In this paper we address the problem of fusing images from many video cameras or a moving video camera. The captured images have obvious motion parallax, but they will be aligned and integrated into a few mosaics with a large field-of-view (FOV) that preserve 3D information. We have developed a geometric representation that can re-organize the orig...
Article
An adaptive panoramic stereo approach for two cooperative mobile platform is presented. There are four key features in the approach: 1) omnidirectional stereovision with an appropriate vertical FOV, and a simple camera calibration method; 2) cooperative mobile platforms for mutual dynamic calibration and best view planning; 3) 3D matching after mea...
Article
A compact visual representation, called the 3D layered, adaptive-resolution, and multi-perspective panorama (LAMP), is proposed for representing large-scale 3D scenes with large variations of depths and obvious occlusions. Two kinds of 3D LAMP representations are proposed: the relief-like LAMP and the image-based LAMP. Both types of LAMPs concisely...
Conference Paper
Correlation-based stereo matching is very important to the generation of 3D terrain model. One of the difficulties in this stereo matching is the selection of the window size, since there are two competing factors that must be balanced in any stereo reconstruction process – perspective distortion and stereo matching error. This paper presents how t...
Conference Paper
A computer vision application can be defined as a sequence of image processing, feature extraction, and interpretation operations that are used to solve a specific task. In most of the computer vision systems this sequence is pre-defined and static. The work presented here shows a dynamic technique for algorithm selection based on both the value of...
Article
This paper presents a panoramic virtual stereo vision approach to the problem of detecting and localizing multiple moving objects (e.g., humans) in an indoor scene. Two panoramic cameras, residing on different mobile platforms, compose a virtual stereo sensor with a flexible baseline. A novel “mutual calibration” algorithm is proposed, where panora...
Article
We present a set of algorithms that recovers detailed building surface structures from large sets of urban images containing severe occlusions and lighting variations. An iterative weighted-average algorithm is introduced to recover high-quality consensus facade texture. 2D and 3D methods are combined to extract microstructures, facilitating urban...
Article
Full-text available
In this paper, we present a new method for automatically and efficiently generating stereoscopic mosaics by seamless registration of images collected by a video camera mounted on an airborne platform. Using a parallel-perspective representation, a pair of geometrically registered stereo mosaics can be precisely constructed under quite general motio...
Article
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Presents the welcome message from the conference proceedings.
Conference Paper
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Traditional generative Markov random fields for segmenting images model the image data and corresponding labels jointly, which requires extensive independence assumptions for tractability. We present the conditional random field for an application in sign detection, using typical scale and orientation selective texture filters and a nonlinear textu...
Conference Paper
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We combine nonlinear diffusion scale-space and geometric deformable models for segmenting lesions in MR images of ischemic stroke patients. Region and boundary information are integrated in a speed function for robust segmentation with the fast marching level set method. A confidence-based model of segmentation captures the significant variability...
Article
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This paper presents a control structure for a general-purpose image understanding system. It addresses the high level of uncertainty in local hypotheses and the computational complexity of image interpretation. The control of vision algorithms is done by an independent subsystem that uses Bayesian networks and utility theory to compute marginal val...
Article
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This paper presents a control structure for general purpose image understanding that addresses both the high level of uncertainty in local hypotheses and the computational complexity of image interpretation. The control of vision algorithms is performed by an independent subsystem that uses Bayesian networks and utility theory to compute the margin...
Article
We present a model-based approach to the automatic detection and reconstruction of buildings from aerial imagery. Buildings are first segmented from the scene in an optical image followed by a reconstruction process that makes use of a corresponding digital elevation map (DEM). Initially, each segmented DEM region likely to contain a building rooft...
Conference Paper
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This paper presents an efficient method for finding salient differential features in images. We argue that the problem of finding salient features among all the possible ones is equivalent to finding outliers in a high-dimensional data set. We apply outlier detection techniques used in data mining to devise a linear time algorithm to extract the sa...
Article
This paper is organized as follows. Section 2 reviews a num- ber of past and present building extraction systems. Section 3 presents a system-level specification of the Ascender system, followed in Section 4 by a breakdown of the building extraction process into its key algorithmiccomponents.Section 5 presents an in-depth experimental evaluation of...
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There have been attempts in a variety of applications to add 3D information into an image-based mosaic representation. Creating stereo mosaics from two rotating cameras was proposed by [Huang & Hung, 1998], and from a single off-center rotating camera by [Ishiguro, et al, 1990], [Peleg & Ben-Ezra, 1999], and by [Shum & Szeliski, 1999]. In these kin...
Article
Textures and microstructures on the surfaces of cultural objects, such as buildings and parking lots, provide important information for many military and civilian applications. The extraction of this information from aerial imagery is dicult due to problems arising from perspective distortion, data de ciency, and corruption caused by shadows and oc...
Article
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Stereo matching is one of the most active research areas in computer vision. While a large number of algorithms for stereo correspondence have been developed, relatively little work has been done on characterizing their performance. In this paper, we ...
Conference Paper
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This paper describes a robust method for recovering an optimal DEM and its variance from multiple, randomly orientated views of a surface. The method generates a set of DEM tiles in a common coordinate system from multiple overlapping images, and then employs the concept of self-consistency to detect and remove errors from the tiles. The clean tile...
Conference Paper
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As the threat of terrorism becomes more prevalent, the need for technological innovations for tighter security rises. Some of the areas where security needs to be increased are at border customs stations, airports, federal buildings, embassies, sporting events, and the like where checkpoints are being set up to inspect vehicles coming onto the prem...
Conference Paper
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Our goal is to improve the way in which Geographic Information System (GIS) databases are created, updated and utilized. We are building software systems that will enable users to rapidly and inexpensively acquire, update, analyze and visualize high-resolution digital elevation maps (DEM), ortho-images, and other GIS products from digital images co...
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The deployment of large, mobile sensor networks presents a wide range of problems, including 1) effectively communicating the important information to a user (or small set of users) without inundating him/her with irrel-evant data, 2) allowing the user to affect the deployment of the network in an intuitive manner, and 3) making this interaction av...