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Papers by Norman Badler

Lecture Notes in Computer Science, 2000

Digital Media: The Future, 2000

We discuss how the combination of a realistic human figure with a high-level behavioral control i... more We discuss how the combination of a realistic human figure with a high-level behavioral control interface allow the construction of detailed simulations of humans performing manual tasks from which inferences about human performance requirements can be made. The Jack human modeling environment facilitates the real-time simulation of humans performing sequences of tasks such as walking, lifting, reaching, and grasping in a complex simulated environment . Analysis capabilities include strength , reachability, and visibility ; moreover results from these tests can affect an unfolding simulation.

This paper describes a collision free path planning and animation system for anthropometric figur... more This paper describes a collision free path planning and animation system for anthropometric figures. It can also take into consideration the strength limit of human figures and plan the motion accordingly. The algorithm breaks down the degrees of freedom of the figure into Cspace groups and computes the free motion for each of these groups in a sequential fashion. It traverses the tree in a depth first order to compute the motion for all the branches. A special playback routine is then used to traverse the tree in a reverse order to playback the final motion. Strength value measures are incorporated directly into the searching function so that path computed will obey strength availability criteria. The planner runs in linear time with respect to the total number of Cspace groups. The planner can interface with other simulation techniques to simulate complex human motions. We believe that the planner would find a path in most cases and is fast enough for practical use in a wide range...

Bonnie L. Webber, University of Pennsylvania Norman I. Badler, University of Pennsylvania F. Brec... more Bonnie L. Webber, University of Pennsylvania Norman I. Badler, University of Pennsylvania F. Breckenridge Baldwin, University of Pennsylvania Welton Becket, University of Pennsylvania Barbara Di Eugenio, University of Pennsylvania Christopher W. Geib, University of Pennsylvania Moon Ryul Jung, University of Pennsylvania Libby Levison, University of Pennsylvania Michael B. Moore, University of Pennsylvania Michael White, University of Pennsylvania

An algorithm for generating shadows with an umbra and penumbra due to distributed light sources i... more An algorithm for generating shadows with an umbra and penumbra due to distributed light sources is presented. The method used is based on the inclusion of the shadow volumes in the object data processed by a depth-buffer visible surface computation. The standard depth-buffer data structure is modified to allow the handling of shadows with a depth-buffer hidden surface algorithm. The algorithm involves breaking the light source up into a set of point sources and superimposing the shadows generated by each point source to obtain the final shadow. Disciplines Computer Engineering | Computer Sciences Comments University of Pennsylvania Department of Computer and Information Science Technical Report No. MSCIS-84-12. This technical report is available at ScholarlyCommons: http://repository.upenn.edu/cis_reports/1006 GENERATING SHADOWS WITH AN UMBRA AND PENUMBRA Lynne Shapiro Norman I. Badler MS.CIS-84-12 Department of Computer and Information Science Moore School/D2 University of Pennsylv...

Animating realistic human agents involves more than just creating movements that look "real&... more Animating realistic human agents involves more than just creating movements that look "real". A principal characteristic of humans is their ability to plan and make decisions based on intentions and the local environmental context. "Animated agents" must therefore react to and deliberate about their environment and other agents. Our agent animation uses various low-level behaviors, sense-control-action loops, high-level planning, and parallel task networks. Several systems we developed will illustrate how these components contribute to the realism and efficacy of human agent animation.

Figure 1: Plans computed for several agents and goals on challenging benchmarks.

Creating animations of a human figure performing a task requires that the agent interact with obj... more Creating animations of a human figure performing a task requires that the agent interact with objects in the environment in a realistic way. Agent-object interaction is not completely specified from a task description alone. In this paper we sketch an architecture for the Object-Specific Reasoner (OSR), an intermediate planning module which tailors high-level plans to the specifics of the agent and objects. As plans are elaborated, the OSR generates a sequence of motion directives which are ultimately executed by a simulator. Descriptions of failures can be used to identify possible tools for the agent to use. An ObjectSpecific Reasoner is necessary in a system which allows an agent, equipped with a set of action behaviors, to interact in a semiautonomous fashion with the world. Keywords object manipulation, motion planning, animation, tools Comments Presented at Toward Physical Interaction and Manipulation, AAAI Spring Symposium Series, 1994. This conference paper is available at S...

We describe a framework for creating animated simulations of virtual human agents. The framework ... more We describe a framework for creating animated simulations of virtual human agents. The framework allows us to capture flexible patterns of activity, as well as reactivity to a changing environment. Both lead to variation in how an animated simulation will be realized. In addition, because different parts of an activity make different demands on an agent's resources and decision-making, our framework allows special-purpose reasoners and planners to be associated with only those phases of an activity where they are needed.

The local matching problem on surfaces is: Given a pair of oriented surfaces in 3-space, find sub... more The local matching problem on surfaces is: Given a pair of oriented surfaces in 3-space, find subsurfaces that are identical or complementary in shape. A heuristic method is presented for local matching that is intended for use on complex curved surfaces (rather than such surfaces as as cubes and cylinders). The method proceeds as follows: (1) Find a small set of points-called "critical points" -on the two surfaces with the property that if p is a critical point and p matches q, then q is also a critical point. The critical points are taken to be local extrema of either Gaussian or mean curvature. (2) Construct a rotation invariant representation around each critical point by intersecting the surface with spheres of standard radius centered around the critical point. For each of the resulting curves of intersection, compute a "distance map" function equal to the distance from a point on the curve to the center of gravity of the curve as a. function of arc length ...

The need to visualize and interpret human body movement data from experiments and simulations has... more The need to visualize and interpret human body movement data from experiments and simulations has led to the development of a new, computerized, three-dimensional representation for the human body. Based on a skeleton of joints and segments, the model is manipulated by specifying joint positions with respect to arbitrary frames of reference. The external form is modelled as the union of overlapping spheres which define the surface of each segment. The properties of the segment and sphere model include: an ability to utilize any connected portion of the body in order to examine selected movements without computing movements of undesired parts , a naming mechanism for describing parts within a segment, and a collision detection algorithm for finding contacts or illegal intersections of the body with itself or other objects. One of the most attractive features of this model is the simple hidden surface removal algorithm. Since spheres always project onto a plane as disks, a solid, shad...

The last few years have seen great maturation in using computer graphics to portray 3D embodied v... more The last few years have seen great maturation in using computer graphics to portray 3D embodied virtual agents. Unlike the off-line, animator-intensive methods used for special effects, real-time embodied agents are expected to interact with us “live.” They can represent other people in a live VR environment such as autonomous helpers, teammates, or tutors and thus enable novel interactive educational and training applications. We should be able to interact and communicate with them, intentionally or not, through natural modalities such as language, facial expressions, and gesture. LiveActor is a virtual training environment where live and virtual people can mutually interact. Various aspects of this system will be discussed, including consistent parameterizations for gesture and facial actions, and the representational basis for character believability, personality, and affect. A Parameterized Action Representation (PAR) allows an agent to act, plan, and reason about its actions or...

In this paper we propose using planar and spherical Bernstein polynomials over triangular domain ... more In this paper we propose using planar and spherical Bernstein polynomials over triangular domain for radiative transfer computations. In the planar domain, we propose using piecewise Bernstein basis functions and symmetric Gaussian quadrature formulas over triangular elements for high quality radiosity solution. In the spherical domain, we propose using piecewise Bernstein basis functions over a geodesic triangulation to represent the radiance function. The representation is intrinsic to the unit sphere, and may be efficiently stored, evaluated, and subdivided by the de Casteljau algorithm. The computation of other fundamental radiometric quantities such as vector irradiance and reflected radiance may be reduced to the integration of the piecewise Bernstein basis functions on the unit sphere. The key result of our work is a simple geometric integration algorithm based on adaptive domain subdivision for the Bernstein-Bezier polynomials over a geodesic triangle on the unit sphere. Com...

We present ADAPT, a flexible platform for designing and authoring functional, purposeful human ch... more We present ADAPT, a flexible platform for designing and authoring functional, purposeful human characters in a rich virtual environment. Our framework incorporates character animation, navigation, and behavior with modular interchangeable components to produce narrative scenes. Our animation system provides locomotion, reaching, gaze tracking, gesturing, sitting, and reactions to external physical forces, and can easily be extended with more functionality due to a decoupled, modular structure. Additionally, our navigation component allows characters to maneuver through a complex environment with predictive steering for dynamic obstacle avoidance. Finally, our behavior framework allows a user to fully leverage a character’s animation and navigation capabilities when authoring both individual decision-making and complex interactions between actors using a centralized, event-driven model.

GUIDE is an interactive graphical system for designing and generating graphical user interfaces. ... more GUIDE is an interactive graphical system for designing and generating graphical user interfaces. It provides flexibility to the system designer while minimizing the amount of code which the designer must write. The GUIDE methodology includes the notions of "tool," "task," and "context." GUIDE encourages designers to tailor their systems to individual users by inclusion of "user profiles," allowing different control paths based on the user's characteristics. GUIDE also provides a method for invoking application routines with parameters. Parameters may be based on user inputs and are computed at invocation time. Help messages are created along with the objects to which they refer. GUIDE handles the overhead required to display help messages. Disciplines Computer Engineering | Computer Sciences Comments University of Pennsylvania Department of Computer and Information Science Technical Report No. MSCIS-85-19. This technical report is availabl...

Creating realistic virtual humans requires models that resemble real humans both visually and beh... more Creating realistic virtual humans requires models that resemble real humans both visually and behaviorally. Physical and behavioral fidelity in human modeling is the focus of research and development work at the University of Pennsylvania's Center for Human Modeling and Simulation. In this article, we briefly describe the Center's human modeling paradigm, Jack®, and our research activities, including Jack's Spreadsheet Anthropometric Scaling System (SASS) and its Free-Form Deformation model.

We used a custom designed tactor suit to provide full body vibrotactile feedback across the human... more We used a custom designed tactor suit to provide full body vibrotactile feedback across the human arm for the purpose of enabling users to perceive a physical sense of collisions in a virtual world. We constructed a 3-D virtual environment to test arm reach movements. We present the results of human subject trials that test the benefit of using vibrotactile feedback for this purpose. Our preliminary results presented here show a small, but distinct, advantage with the use of tactors. With additional refinements to the system, improved performance results can be obtained. Comments University of Pennsylvania Department of Computer and Information Science Technical Report No. MSCIS-03-45. This technical report is available at ScholarlyCommons: http://repository.upenn.edu/cis_reports/67 Enhanced Collision Perception Using Tactile Feedback Aaron Bloomfield Norman I. Badler Center for Human Modeling and Simulation University of Pennsylvania {aaronb, badler} @cis.upenn.edu

Lecture Notes in Computer Science, 2000

Digital Media: The Future, 2000

We discuss how the combination of a realistic human figure with a high-level behavioral control i... more We discuss how the combination of a realistic human figure with a high-level behavioral control interface allow the construction of detailed simulations of humans performing manual tasks from which inferences about human performance requirements can be made. The Jack human modeling environment facilitates the real-time simulation of humans performing sequences of tasks such as walking, lifting, reaching, and grasping in a complex simulated environment . Analysis capabilities include strength , reachability, and visibility ; moreover results from these tests can affect an unfolding simulation.

This paper describes a collision free path planning and animation system for anthropometric figur... more This paper describes a collision free path planning and animation system for anthropometric figures. It can also take into consideration the strength limit of human figures and plan the motion accordingly. The algorithm breaks down the degrees of freedom of the figure into Cspace groups and computes the free motion for each of these groups in a sequential fashion. It traverses the tree in a depth first order to compute the motion for all the branches. A special playback routine is then used to traverse the tree in a reverse order to playback the final motion. Strength value measures are incorporated directly into the searching function so that path computed will obey strength availability criteria. The planner runs in linear time with respect to the total number of Cspace groups. The planner can interface with other simulation techniques to simulate complex human motions. We believe that the planner would find a path in most cases and is fast enough for practical use in a wide range...

Bonnie L. Webber, University of Pennsylvania Norman I. Badler, University of Pennsylvania F. Brec... more Bonnie L. Webber, University of Pennsylvania Norman I. Badler, University of Pennsylvania F. Breckenridge Baldwin, University of Pennsylvania Welton Becket, University of Pennsylvania Barbara Di Eugenio, University of Pennsylvania Christopher W. Geib, University of Pennsylvania Moon Ryul Jung, University of Pennsylvania Libby Levison, University of Pennsylvania Michael B. Moore, University of Pennsylvania Michael White, University of Pennsylvania

An algorithm for generating shadows with an umbra and penumbra due to distributed light sources i... more An algorithm for generating shadows with an umbra and penumbra due to distributed light sources is presented. The method used is based on the inclusion of the shadow volumes in the object data processed by a depth-buffer visible surface computation. The standard depth-buffer data structure is modified to allow the handling of shadows with a depth-buffer hidden surface algorithm. The algorithm involves breaking the light source up into a set of point sources and superimposing the shadows generated by each point source to obtain the final shadow. Disciplines Computer Engineering | Computer Sciences Comments University of Pennsylvania Department of Computer and Information Science Technical Report No. MSCIS-84-12. This technical report is available at ScholarlyCommons: http://repository.upenn.edu/cis_reports/1006 GENERATING SHADOWS WITH AN UMBRA AND PENUMBRA Lynne Shapiro Norman I. Badler MS.CIS-84-12 Department of Computer and Information Science Moore School/D2 University of Pennsylv...

Animating realistic human agents involves more than just creating movements that look "real&... more Animating realistic human agents involves more than just creating movements that look "real". A principal characteristic of humans is their ability to plan and make decisions based on intentions and the local environmental context. "Animated agents" must therefore react to and deliberate about their environment and other agents. Our agent animation uses various low-level behaviors, sense-control-action loops, high-level planning, and parallel task networks. Several systems we developed will illustrate how these components contribute to the realism and efficacy of human agent animation.

Figure 1: Plans computed for several agents and goals on challenging benchmarks.

Creating animations of a human figure performing a task requires that the agent interact with obj... more Creating animations of a human figure performing a task requires that the agent interact with objects in the environment in a realistic way. Agent-object interaction is not completely specified from a task description alone. In this paper we sketch an architecture for the Object-Specific Reasoner (OSR), an intermediate planning module which tailors high-level plans to the specifics of the agent and objects. As plans are elaborated, the OSR generates a sequence of motion directives which are ultimately executed by a simulator. Descriptions of failures can be used to identify possible tools for the agent to use. An ObjectSpecific Reasoner is necessary in a system which allows an agent, equipped with a set of action behaviors, to interact in a semiautonomous fashion with the world. Keywords object manipulation, motion planning, animation, tools Comments Presented at Toward Physical Interaction and Manipulation, AAAI Spring Symposium Series, 1994. This conference paper is available at S...

We describe a framework for creating animated simulations of virtual human agents. The framework ... more We describe a framework for creating animated simulations of virtual human agents. The framework allows us to capture flexible patterns of activity, as well as reactivity to a changing environment. Both lead to variation in how an animated simulation will be realized. In addition, because different parts of an activity make different demands on an agent's resources and decision-making, our framework allows special-purpose reasoners and planners to be associated with only those phases of an activity where they are needed.

The local matching problem on surfaces is: Given a pair of oriented surfaces in 3-space, find sub... more The local matching problem on surfaces is: Given a pair of oriented surfaces in 3-space, find subsurfaces that are identical or complementary in shape. A heuristic method is presented for local matching that is intended for use on complex curved surfaces (rather than such surfaces as as cubes and cylinders). The method proceeds as follows: (1) Find a small set of points-called "critical points" -on the two surfaces with the property that if p is a critical point and p matches q, then q is also a critical point. The critical points are taken to be local extrema of either Gaussian or mean curvature. (2) Construct a rotation invariant representation around each critical point by intersecting the surface with spheres of standard radius centered around the critical point. For each of the resulting curves of intersection, compute a "distance map" function equal to the distance from a point on the curve to the center of gravity of the curve as a. function of arc length ...

The need to visualize and interpret human body movement data from experiments and simulations has... more The need to visualize and interpret human body movement data from experiments and simulations has led to the development of a new, computerized, three-dimensional representation for the human body. Based on a skeleton of joints and segments, the model is manipulated by specifying joint positions with respect to arbitrary frames of reference. The external form is modelled as the union of overlapping spheres which define the surface of each segment. The properties of the segment and sphere model include: an ability to utilize any connected portion of the body in order to examine selected movements without computing movements of undesired parts , a naming mechanism for describing parts within a segment, and a collision detection algorithm for finding contacts or illegal intersections of the body with itself or other objects. One of the most attractive features of this model is the simple hidden surface removal algorithm. Since spheres always project onto a plane as disks, a solid, shad...

The last few years have seen great maturation in using computer graphics to portray 3D embodied v... more The last few years have seen great maturation in using computer graphics to portray 3D embodied virtual agents. Unlike the off-line, animator-intensive methods used for special effects, real-time embodied agents are expected to interact with us “live.” They can represent other people in a live VR environment such as autonomous helpers, teammates, or tutors and thus enable novel interactive educational and training applications. We should be able to interact and communicate with them, intentionally or not, through natural modalities such as language, facial expressions, and gesture. LiveActor is a virtual training environment where live and virtual people can mutually interact. Various aspects of this system will be discussed, including consistent parameterizations for gesture and facial actions, and the representational basis for character believability, personality, and affect. A Parameterized Action Representation (PAR) allows an agent to act, plan, and reason about its actions or...

In this paper we propose using planar and spherical Bernstein polynomials over triangular domain ... more In this paper we propose using planar and spherical Bernstein polynomials over triangular domain for radiative transfer computations. In the planar domain, we propose using piecewise Bernstein basis functions and symmetric Gaussian quadrature formulas over triangular elements for high quality radiosity solution. In the spherical domain, we propose using piecewise Bernstein basis functions over a geodesic triangulation to represent the radiance function. The representation is intrinsic to the unit sphere, and may be efficiently stored, evaluated, and subdivided by the de Casteljau algorithm. The computation of other fundamental radiometric quantities such as vector irradiance and reflected radiance may be reduced to the integration of the piecewise Bernstein basis functions on the unit sphere. The key result of our work is a simple geometric integration algorithm based on adaptive domain subdivision for the Bernstein-Bezier polynomials over a geodesic triangle on the unit sphere. Com...

We present ADAPT, a flexible platform for designing and authoring functional, purposeful human ch... more We present ADAPT, a flexible platform for designing and authoring functional, purposeful human characters in a rich virtual environment. Our framework incorporates character animation, navigation, and behavior with modular interchangeable components to produce narrative scenes. Our animation system provides locomotion, reaching, gaze tracking, gesturing, sitting, and reactions to external physical forces, and can easily be extended with more functionality due to a decoupled, modular structure. Additionally, our navigation component allows characters to maneuver through a complex environment with predictive steering for dynamic obstacle avoidance. Finally, our behavior framework allows a user to fully leverage a character’s animation and navigation capabilities when authoring both individual decision-making and complex interactions between actors using a centralized, event-driven model.

GUIDE is an interactive graphical system for designing and generating graphical user interfaces. ... more GUIDE is an interactive graphical system for designing and generating graphical user interfaces. It provides flexibility to the system designer while minimizing the amount of code which the designer must write. The GUIDE methodology includes the notions of "tool," "task," and "context." GUIDE encourages designers to tailor their systems to individual users by inclusion of "user profiles," allowing different control paths based on the user's characteristics. GUIDE also provides a method for invoking application routines with parameters. Parameters may be based on user inputs and are computed at invocation time. Help messages are created along with the objects to which they refer. GUIDE handles the overhead required to display help messages. Disciplines Computer Engineering | Computer Sciences Comments University of Pennsylvania Department of Computer and Information Science Technical Report No. MSCIS-85-19. This technical report is availabl...

Creating realistic virtual humans requires models that resemble real humans both visually and beh... more Creating realistic virtual humans requires models that resemble real humans both visually and behaviorally. Physical and behavioral fidelity in human modeling is the focus of research and development work at the University of Pennsylvania's Center for Human Modeling and Simulation. In this article, we briefly describe the Center's human modeling paradigm, Jack®, and our research activities, including Jack's Spreadsheet Anthropometric Scaling System (SASS) and its Free-Form Deformation model.

We used a custom designed tactor suit to provide full body vibrotactile feedback across the human... more We used a custom designed tactor suit to provide full body vibrotactile feedback across the human arm for the purpose of enabling users to perceive a physical sense of collisions in a virtual world. We constructed a 3-D virtual environment to test arm reach movements. We present the results of human subject trials that test the benefit of using vibrotactile feedback for this purpose. Our preliminary results presented here show a small, but distinct, advantage with the use of tactors. With additional refinements to the system, improved performance results can be obtained. Comments University of Pennsylvania Department of Computer and Information Science Technical Report No. MSCIS-03-45. This technical report is available at ScholarlyCommons: http://repository.upenn.edu/cis_reports/67 Enhanced Collision Perception Using Tactile Feedback Aaron Bloomfield Norman I. Badler Center for Human Modeling and Simulation University of Pennsylvania {aaronb, badler} @cis.upenn.edu

An efficient computation of 3D workspaces for redundant manipulators is based on a "hybrid" al- g... more An efficient computation of 3D workspaces for redundant manipulators is based on a "hybrid" al- gorithm between direct kinematics and screw theory. Direct kinematics enjoys low computational cost, but needs edge detection algorithms when workspace boundaries are needed. Screw theory has exponential computational cost per workspace point, but does not need edge detection. Screw theory allows computing workspace points in prespecified directions, while direct kinematics does not. Applications of the algorithm are discussed.