Marcelo Kallmann

Modeling Objects for Interaction Tasks

This paper presents a new approach to model general interactions between virtual human agents and objects in virtual worlds. The proposed framework is designed to deal with many of the possible interactions that may arise while simulating a virtual human performing common tasks in a virtual environment. The idea is to include within the object description, all the necessary information to describe how to interact with it. For this, a feature modeling approach is used, by means of a graphical user interface program, to identify object interaction features. Moving parts, functionality instructions and interaction locations are examples of some considered features. Following this approach, the control of the simulation is decentralized from the main animation control, in the sense that some local instructions on how to deal with the object are encapsulated within the object itself. To illustrate the approach, some examples are shown and discussed.

Planning collision-free reaching motions for interactive object manipulation and grasping

We present new techniques that use motion planning algorithms based on probabilistic roadmaps to control 22 degrees of freedom (DOFs) of human‐like characters in interactive applications. Our main purpose is the automatic synthesis of collision‐free reaching motions for both arms, with automatic column control and leg flexion. Generated motions are collision‐free, in equilibrium, and respect articulation range limits. In order to deal with the high (22) dimension of our configuration space, we bias the random distribution of configurations to favor postures most useful for reaching and grasping. In addition, extensions are presented in order to interactively generate object manipulation sequences: a probabilistic inverse kinematics solver for proposing goal postures matching pre‐designed grasps; dynamic update of roadmaps when obstacles change position; online planning of object location transfer; and an automatic stepping control to enlarge the characters reachable space. This is, to our knowledge, the first time probabilistic planning techniques are used to automatically generate collision‐free reaching motions involving the entire body of a human‐like character at interactive frame rates.

Motion capture from inertial sensing for untethered humanoid teleoperation

We describe the design of a modular system for untethered real-time kinematic motion capture using sensors with inertial measuring units (IMU). Our system is comprised of a set of small and lightweight sensors. Each sensor provides its own global orientation (3 degrees of freedom) and is physically and computationally independent, requiring only external communication. Orientation information from sensors is communicated via wireless to host computer for processing. We present results of the real-time usage of our untethered motion capture system for teleoperating the NASA Robonaut. We also discuss potential applications for untethered motion capture with respect to humanoid robotics.

Direct 3D interaction with smart objects

Performing 3D interactions with virtual objects easily becomes a complex task, limiting the implementation of larger applications. In order to overcome some of these limitations, this paper describes a framework where the virtual object aids the user to accomplish a pre-programmed possible interaction. Such objects are called Smart Objects, in the sense that they know how the user can interact with them, giving clues to aid the interaction. We show how such objects are constructed, and exemplify the framework with an application where the user, wearing a data glove, can easily open and close drawers of some furniture.

A behavioral interface to simulate agent-object interactions in real time

The paper shows a novel approach to model and control interactive objects for simulations with virtual human agents when real time interactivity is essential. A general conceptualization is made to model objects with behaviors that can provide: information about their functionality changes in appearance from parameterized deformations, and a complete plan for each possible interaction with a virtual human. Such behaviors are described with simple primitive commands, following the actual trend of many standard scene graph file formats that connects language with movements and events to create interactive animations. In our case, special attention is given to correctly interpret object behaviors in parallel; a situation that arrives when many human agents interact at the same time with one same object.

A paradigm for controlling virtual humans in urban environment simulations

This paper presents a new architecture for simulating virtual humans in complex urban environments. The approach is based on the integration of six modules. Four key modules are used in order to manage environmental data, simulate human crowds, control interactions between virtual humans and objects, and generate tasks based on a rule-based behavioral model. The communication between these modules is made through a client/server system. Finally, all low-level virtual human actions are delegated to a single motion and behavioral control module. Our architecture combines various human and object simulation aspects, based on the coherent extraction and classification of information froma virtual city database. This architecture is discussed in this paper, together with a detailed case study example.

Fully Dynamic Constrained Delaunay Triangulations

We present algorithms for the efficient insertion and removal of constraints in Delaunay Triangulations. Constraints are considered to be points or any kind of polygonal lines. Degenerations such as edge overlapping, self-intersections or duplicated points are allowed and are automatically detected and fixed on line. As a result, a fully Dynamic Constrained Delaunay Triangulation is achieved, able to efficiently maintain a consistent triangulated representation of dynamic polygonal domains. Several applications in the fields of data visualization, reconstruction, geographic information systems and collision-free path planning are discussed.

Modeling Behaviors of Interactive Objects for Real-Time Virtual Environments

Real-time 3D graphics are being extensively used to build interactive virtual environments for a number of different applications. In many situations, virtual objects are required to exhibit complex behaviors and the use of a versatile behavioral programming methodology is required. This paper presents a feature modeling approach to define behavioral information of virtual objects, giving special attention to their capabilities of interaction with virtual human actors. The proposed method is based on a complete definition and representation of interactive objects, which are called smart objects. This representation is based on the description of interaction features: parts, movements, graspable sites, functionalities, purposes, etc., including a behavioral automata based on scripts and graphical state machines.

Shortest paths with arbitrary clearance from navigation meshes

This paper addresses the problem of efficiently computing optimal paths of arbitrary clearance from a polygonal representation of a given virtual environment. Key to the proposed method is a new type of triangulated navigation mesh, called a Local Clearance Triangulation, which enables the efficient and correct determination if a disc of arbitrary size can pass through any narrow passages of the mesh. The proposed approach uniquely balances speed of computation and optimality of paths by first computing high-quality locally shortest paths efficiently in optimal time. Only in case global optimality is needed, an extended search will gradually improve the current path (if not already the global optimal) until the globally shortest one is determined. The presented method represents the first solution correctly extracting shortest paths of arbitrary clearance directly from a triangulated environment.

A framework for rapid evaluation of prototypes with augmented reality

In this paper we present a new framework in Augmented Reality context for rapid evaluation of prototypes before manufacture. The design of such prototypes is a time consuming process, leading t o the need of previous evaluation in realistic interactive environments. We have extended the definition of modelling object geometry with modelling object behaviour being able to evaluate them in a mixed environment. Such enhancements allow the development of tools and methods to test object behaviour, and perform interactions between real virtual humans and complex real and virtual objects.We propose a framework for testing the design of objects i an augmented reality context, where a virtual human is able to perform evaluation tests with an object composed of rea and virtual components. In this paper our framework is described and a case study is presented.