Catálogo de publicaciones - libros

Shading has a great impact to the human perception of 3D objects. Thus, in order to create or to deform a 3D object, it seems natural to manipulate its perceived shading. This paper presents a new solution for the software implementation of this idea. Our approach is based on the ability of a user to coarsely draw a shading, under different lighting directions. With this intuitive process, users can create or edit a height field (locally or globally), that will correspond to the drawn shading values. Moreover, we present the possibility to edit the shading intensity by means of a specular reflectance model.

This work focuses on interface design for supporting users of instrumented environments to interact with virtual information embedded in the real world. A gesture-based interaction paradigm is presented and the prototype of an interface providing affordances for gesture-based direct manipulation of digital information is described.

During the last decade research groups as well as a number of commercial software developers have started to deploy embodied conversational characters in the user interface especially in those application areas where a close emulation of multimodal human-human communication is needed. Most of these characters have one thing in common: In order to enter the user’s physical world, they need to be physical themselves. The paper focuses on challenges that arise when embedding synthetic conversational agents in the user’s physical world. We will start from work on synthetic agents that populate virtual worlds and anthropomorphic robots that inhabit physical worlds and discuss how the two areas need to be combined in order to populate physical worlds with synthetic characters. Finally, we will report on so-called traversable interfaces that allow agents to cross the border from the physical space to the virtual space and vice versa.

We describe an immersive music visualization application which enables interaction between a live musician and a responsive virtual character. The character reacts to live performance in such a way that it appears to be experiencing an emotional response to the music it ‘hears.’ We modify an existing tonal music encoding strategy in order to define how the character perceives and organizes musical information. We reference existing research correlating musical structures and composers’ emotional intention in order to simulate cognitive processes capable of inferring emotional meaning from music. The ANIMUS framework is used to define a synthetic character who visualizes its perception and cognition of musical input by exhibiting responsive behaviour expressed through animation.

This article describes the integration of knowledge based techniques into simulative Virtual Reality (VR) applications. The approach is motivated using multimodal Virtual Construction as an example domain. An abstract Knowledge Representation Layer (KRL) is proposed which is expressive enough to define all necessary data for diverse simulation tasks and which additionally provides a base formalism for the integration of Artificial Intelligence (AI) representations. The KRL supports two different implementation methods. The first method uses XSLT processing to transform the external KRL format into the representation formats of the diverse target systems. The second method implements the KRL using a functionally extendable semantic network. The semantic net library is tailored for real time simulation systems where it interconnects the required simulation modules and establishes access to the knowledge representations inside the simulation loop. The KRL promotes a novel object model for simulated objects called Semantic Entities which provides a uniform access to the KRL and which allows extensive system modularization. The KRL approach is demonstrated in two simulation areas. First, a generalized scene graph representation is presented which introduces an abstract definition and implementation of geometric node interrelations. It supports scene and application structures which can not be expressed using common scene hierarchies or field route concepts. Second, the KRL’s expressiveness is demonstrated in the design of multimodal interactions. Here, the KRL defines the knowledge particularly required during the semantic analysis of multimodal user utterances.

Modelling, animation and rendering has dominated research computer graphics yielding increasingly rich and realistic virtual worlds. The complexity, richness and quality of the virtual worlds are viewed through a single media that is a virtual camera. In order to properly convey information, whether related to the characters in a scene, the aesthetics of the composition or the emotional impact of the lighting, particular attention must be given to how the camera is positioned and moved. This paper presents an overview of automated camera planning techniques. After analyzing the requirements with respect to shot properties, we review the solution techniques and present a broad classification of existing approaches. We identify the principal shortcomings of existing techniques and propose a set of objectives for research into automated camera planning.

This paper describes the process by which we have constructed an adaptive system for external representation (ER) selection support, designed to enhance users’ ER reasoning performance. We describe how our user model has been constructed – it is a Bayesian network with values seeded from data derived from experimental studies. The studies examined the effects of users’ background knowledge-of-external representations (KER) upon performance and their preferences for particular information display forms across a range of database query types.

In this paper we tackle the main problem presented by the majority of Information Visualization techniques, that is, the limited number of data items that can be visualized simultaneously. Our approach proposes an innovative and interactive systematization that can augment the potential for data presentation by utilizing multiple views. These multiple presentation views are kept linked according to the analytical decisions took by the user and are tracked in a tree-like structure. Our emphasis is on developing an intuitive yet powerful system that helps the user to browse the information and to make decisions based both on overview and on detailed perspectives of the data under analysis. The visualization tree keeps track of the interactive actions taken by the user without losing context.

The article discusses an application of the Representational Epistemology (REEP) approach to the development of a graphical interface for production planning and scheduling called ROLLOUT. The paper reports two studies conducted with bakery planning and scheduling professionals that focus on the cognitive support provided by ROLLOUT in reasoning about the spatial-temporal structure of production processes. The results of the first task suggest that given tabular representations, participants frequently make errors in decisions about the assignment of production sequences in terms of their temporal structure. The errors are more frequent for problems that require reasoning about consequences backwards rather than forwards in time. The second task evaluated participants’ performance at improving production schedules on ROLLOUT. Log files revealed that participants improved the temporal efficiency of the schedule by making edit operations involving frequent repetitions with the same instances that tended to change the time and not the order of production. The authors propose that participants were able to effectively use ROLLOUT to generate an efficient schedule at increasing levels of precision by using the representation to test out and re-evaluate concurrent what-if scenarios. The advantages of ROLLOUT for such tasks are explained in terms of (1) the presence of diagrammatic constraints that preserve domain relations, (2) the presence of a global interpretive scheme, and (3) the degree of meaningful conceptual interrelations available in the representation.

We present a method to generate glyphs which convey complex information in graphical form. A glyph has a linear geometry which is specified using geometric operations, each represented by characters nested in a string. This format allows several glyph strings to be concatenated, resulting in more complex geometries. We explore automatic generation of a large number of glyphs using a genetic algorithm. To measure the visual distinctness between two glyph geometries, we use the iterative closest point algorithm. We apply these methods to create two different types of representations for biological proteins, transforming the rich data describing their various characteristics into graphical form. The representations are automatically built from a finite set of glyphs, which have been created manually or using the genetic algorithm.