Papers by Christopher Connolly
Foundations of Digital Games, 2015
In this paper, we examine how behavioral characteristics related to spatial mobility and movement... more In this paper, we examine how behavioral characteristics related to spatial mobility and movement in a multi-player game may differ between male and female players. The study formed part of a large international research project called VERUS. Data was gathered from 380 players in a specially-designed multi-level fantasy game. A machine learning approach was used to identify association rules to differentiate the respective gamer behaviors. Using appropriate threshold levels, the rules achieved a precision of 99% for males and 89% for females. We believe that this quantitative technique offers an innovative way to characterize the gender differences associated with how people interpret and experience their virtual settings.
Proceedings of SPIE, Aug 1, 1991
ABSTRACT Model-based recognition usually begs the question of generation of suitable object model... more ABSTRACT Model-based recognition usually begs the question of generation of suitable object models. Our solid models are face/edge/vertex representations where the faces form 2-cycle(s) properly enclosing a region of 3-D space. These models facilitate generation of rendered images, computing numeric features for the object, and answering questions such as feature visibility for a given orientation. In this paper, a process for the generation of solid models from 2-D images, range images, or line drawings is described. Examples are provided.
Springer eBooks, 1988
With the recent increased interest in model-based matching1, 2, 3, 4 has appeared a concomitant i... more With the recent increased interest in model-based matching1, 2, 3, 4 has appeared a concomitant interest in automated model creation.5, 6, 7 Ideally, models should be constructed automatically from a scene, so that the process of matching (for example) would require no human intervention. In any case when computer models of an object are needed but are not available, it would be convenient to have an automatic method for constructing the models from image data.
Analysis of massive track datasets is a challenging problem, especially when examining n-way rela... more Analysis of massive track datasets is a challenging problem, especially when examining n-way relations inherent in social networks. In this paper, we use the Mitsubishi track database to examine the usefulness of three types of interaction features observable in tracklet networks. We explore ways in which social network information can be extracted and visualized using a statistical sampling of these features from a very large track dataset, with very little ground truth or outside knowledge. Special attention is given to methods that are likely to scale well beyond the size of the Mitsubishi dataset.
Proceedings of SPIE, Feb 1, 1990
ABSTRACT A frequent problem in the use of potential functions for robot path planning is that loc... more ABSTRACT A frequent problem in the use of potential functions for robot path planning is that local minima often occur. These local minima may be eliminated by judicious selection of potential functions for goals and obstacles. Specifically, harmonic functions may be used without introducing such minima. While there are analytic, easily superposed solutions for impenetrable point obstacles, this is not the case for impenetrable obstacles with finite, nonzero extent (e.g., walls). Instead, numerical methods that are well suited to massively parallel computation can be used.
A method is presented for planning obstacle-avoiding paths for a system which exhibits nonholonom... more A method is presented for planning obstacle-avoiding paths for a system which exhibits nonholonomic constraints. The method is based on the use of harmonic functions. Linear constraints on the velocity of a nonholonomic system can be directly expressed as Neumann boundary conditions for a harmonic function. Such boundary conditions are easily represented in a resistive network. The resulting potential represents an integration of nonholonomic constraints over an admissible subset of con guration space. The method is applied to path planning for simple wheeled vehicles.
Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information
Biological Cybernetics, Jun 23, 2000
The juxtaposition of hypokinetic and hyperkinetic symptoms in Parkinson's disease (PD) presents a... more The juxtaposition of hypokinetic and hyperkinetic symptoms in Parkinson's disease (PD) presents a challenge in modeling the basal ganglia. We propose a model of the striatum that can account for the mixture of symptoms seen in PD. In the model, the problem of motor planning is cast in terms of a particle in a potential, where potentials are generated internally in striatal modules, subject to aerent control. Planned movement is governed by Hamilton's equations, where potential energy is supplied by potentials expressed in the striatum. To test the model in realistic situations, a dynamic simulation of a two-link robot arm was used. Normal movement is modeled and shown to exhibit observed experimental properties. Symptoms of PD are reproduced by modeling hypothetical consequences of PD pathology.
Neuroscience Letters, 2007
Learning is important for humans and can be disrupted by disease. However, the essence of how lea... more Learning is important for humans and can be disrupted by disease. However, the essence of how learning may be represented within a neuronal network is still elusive. Spike trains generated by neurons have been demonstrated to carry information which is relevant for learning. The present study uses well-established mutual information (MI) analysis techniques to better understand learning within neuronal ensembles. Spike trains in tetrode recordings from the dorso-lateral striatum were used for computing MI as rats learnt a T-maze procedural task. We demonstrate that in in-vivo recordings the growth of MI is reflected in the behavioral response as learning proceeds. These changes in MI are seen to correspond to three phases, a low MI value, namely early learning, a rapid increase in MI value, task-acquisition and stabilization of MI, over-training. Over multiple training sessions, small changes in MI within the neuronal network suddenly produce a big change in ensemble MI during the task acquisition phase. This phase represents the "tipping point" in the neuronal network where the MI growth builds habits during motor learning in the striatum.
Neural Information Processing Systems, Nov 29, 1993
While exploring to find better solutions, an agent performing online reinforcement learning (RL) ... more While exploring to find better solutions, an agent performing online reinforcement learning (RL) can perform worse than is acceptable. In some cases, exploration might have unsafe, or even catastrophic, results, often modeled in terms of reaching 'failure' states of the agent's environment. This paper presents a method that uses domain knowledge to reduce the number of failures during exploration. This method formulates the set of actions from which the RL agent composes a control policy to ensure that exploration is conducted in a policy space that excludes most of the unacceptable policies. The resulting action set has a more abstract relationship to the task being solved than is common in many applications of RL. Although the cost of this added safety is that learning may result in a suboptimal solution, we argue that this is an appropriate tradeoff in many problems. We illustrate this method in the domain of motion planning.
ABSTRACT There are situations in which one would like to know a good sequence of range-image view... more ABSTRACT There are situations in which one would like to know a good sequence of range-image views for obtaining a complete model of a scene. This paper describes two algorithms which use partial octree models to determine the "best" next view to take.
Toward a Path CO-Processor for ,4utomated Vehicle Control * ... Roderic A. Grupen Chris I. Connol... more Toward a Path CO-Processor for ,4utomated Vehicle Control * ... Roderic A. Grupen Chris I. Connolly Kamal X. Souccar Wayne P. Burleson Computer Science SRI International Computer Science Elec. and Comp: Eng ... University of Massachusetts, Amherst, M-4 01003 ...
Neural Processing Letters, Apr 1, 2006
This paper provides new insights regarding the transfer of information between input signal and t... more This paper provides new insights regarding the transfer of information between input signal and the output of neurons. Simulations of the Hodgkin-Huxley (HH) model combined with computational techniques are used to estimate this transfer of information. Our analysis shows that comparatively, mutual information (MI) between input signal and sodium flux is about two times that between input signal and output spikes during each spike within a millisecond-level time domain. This higher transfer of information provided by ionic fluxes extends the working frequency domain of neural cells beyond those accessible to information transfer within spikes alone.
International Journal of Computer Vision, Dec 1, 1992
Methods for constructing face-edge-vertex models of objects directly from image data are presente... more Methods for constructing face-edge-vertex models of objects directly from image data are presented. These methods, applicable to both range and intensity data, produce refined models using multiple images. Each model bounds the actual positions of surfaces on the object. The techniques rely on topologically significant image features to generate bounding volumes for the object surfaces. Potentially occupied volumes obtained from the multiple image viewpoints are intersected to form a cumulative description of potential surface positions. In conjunction with certain coherence and visibility assumptions, a model can be produced with little or no ambiguity. Typically, several well-chosen views will produce a good approximation to the object under consideration. Illustrative examples of building models from multiple range and intensity images are provided.
Biological Cybernetics, Apr 1, 1993
A model is presented for the operation of the striatum. The model posits that the basal ganglia a... more A model is presented for the operation of the striatum. The model posits that the basal ganglia are responsible for driving smooth transitions of state for an organism. We propose that this is accomplished through the computation of a potential function within the striatum on which a gradient descent is performed toward the goal state. The model suggests that various somatotopic regions of the striatum correspond to state spaces, each of which pertains to a di erent aspect of the organism. This paper discusses this model only in the context of motor control, i.e., egomotion and limb movement. The model appears to account for a variety of experimental results, and for some unusual properties of the striatum.
A method for planning smooth robot paths is presented. The method relies on the use of Laplace's ... more A method for planning smooth robot paths is presented. The method relies on the use of Laplace's Equation to constrain the generation of a potential function over regions of the configuration space of an effector. Once the function is computed, paths may be found very quickly. These functions do not exhibit the local minima which plague the potential field method. Unlike decompositional and algebraic techniques, Laplace's Equation is very well suited to computation on massively parallel architectures.
We describe a system for converting RADIUS site models into a Web-accessible form. Once converted... more We describe a system for converting RADIUS site models into a Web-accessible form. Once converted, the site models can be downloaded and viewed with standard, off-the-shelf Web browsers. Site models themselves are represented in the Virtual Reality Modeling Language (VRML). Each feature in the site model is cross-linked to a Web page that describes that feature in more detail, including image chips and collateral information. A demonstration of work described in this paper is accessible via the URL http://www.ai.sri. com/˜connolly/pathfinder.
Analysis of massive track datasets is a challenging problem, especially when examining n-way rela... more Analysis of massive track datasets is a challenging problem, especially when examining n-way relations inherent in social networks. In this paper, we explore ways in which stable properties of sensor observations can be extracted and visualized using a statistical sampling of features from a very large track dataset, using very little ground truth or outside knowledge. Special attention is given to methods that are likely to scale well beyond the size of the Mitsubishi dataset.
THE `GEOMETER'' MODELING SYSTEM IS DESCRIBED. THE SYSTEM IS DESIGNED TO MANIPULATE SOLID ... more THE `GEOMETER'' MODELING SYSTEM IS DESCRIBED. THE SYSTEM IS DESIGNED TO MANIPULATE SOLID MODELS FOR A VARIETY OF PURPOSES. `GEOMETER'' ALSO SUPPORTS POLYNOMIAL AND TRANSCENDENTAL FUNCTION MANIPULATION, INCLUDING METHODS FOR SOLVING SYSTEMS OF POLYNOMIAL EQUATIONS. THE APPLICATIONS FOR SUCH METHODS IN THE CONTEXT OF SOLID MODELING AND COMPUTER VISION ARE ALSO DISCUSSED.
Uploads
Papers by Christopher Connolly