Knut Hartmann

Floating Labels: Applying Dynamic Potential Fields for Label Layout

This paper introduces a new method to determine appealing placements of textual annotations for complex-shaped geometric models. It employs dynamic potential fields, which consider attractive and repulsive forces between pictorial elements and their textual labels. Several label candidates are computed and evaluated according to weighted penalty functions. The individual weights can be adjusted according to global design decisions or user preferences. Moreover, the user can re-arrange individual labels whereas the system re-adjusts the remaining labels. The method is demonstrated by the Floating Label system.

Illustrative shadows: integrating 3D and 2D information displays

Many exploration and manipulation tasks benefit from a coherent integration of multiple views onto complex information spaces. This paper proposes the concept of Illustrative Shadows for a tight integration of interactive 3D graphics and schematic depictions using the shadow metaphor. The shadow metaphor provides an intuitive visual link between 3D and 2D visualizations integrating the different displays into one combined information display. Users interactively explore spatial relations in realistic shaded virtual models while functional correlations and additional textual information are presented on additional projection layers using a semantic network approach. Manipulations of one visualization immediately influence the others, resulting in an in-formationally and perceptibly coherent presentation

Metrics for functional and aesthetic label layouts

Co-referential relations between textual and visual elements in illustrations can be encoded efficiently through textual labels. The labels support students to learn unknown terms and focus their attention on important aspects of the illustration; while a functional and aesthetic label layout aims at guaranteeing the readability of text strokes as well as preventing the referential mismatches. By analyzing a corpus of complex label layouts in hand-drawn illustrations, a classification of label layout styles and several metrics for functional requirements and aesthetic attributes were extracted. As the choice of a specific layout style seems largely determined by individual preferences, a real-time layout algorithm for internal and external labels balances conflicting user-specific requirements, functional and aesthetic attributes.

Agent-Based Annotation of Interactive 3D Visualizations

This paper presents a novel real-time algorithm to integrate internal and external labels of arbitrary size into 3D visualizations. Moreover, comprehensive dynamic content can be displayed in annotation boxes. Our system employs multiple metrics in order to achieve an effective and aesthetic label layout with adjustable weights. The layout algorithm employs several heuristics to reduce the search space of a complex layout task. Initial layouts are refined by label agents, i.e., local strategies to optimize the layout and to minimize the flow of layout elements in subsequent frames.

Interactive audiobooks: combining narratives with game elements

The authoring and the design of immersive, non-linear plots remains one of the main challenges in interactive digital storytelling. This paper introduces the concept of interactive audiobooks, which combines the potential of complex (non-)linear narratives (e.g. books and radio plays) with interactive elements from computer games. The design concentrates on a flexible degree of interaction, in a way that the listeners experience ranges between a passive listening to an interactive audio-only computer game. In this paper we discuss the story-engine used in interactive audiobooks, as well as present an authoring framework along several design guidelines to create them. Finally, we demonstrate the capabilities of our system with an adaptation of a short story from Edgar Allen Poe.

Form follows function: aesthetic interactive labels

Labels effectively convey co-referential relations between textual and visual elements and are a powerful tool to support learning tasks. Therefore, almost all illustrations in scientific or technical documents employ a large number of labels. This paper introduces a novel approach to integrate internal and external labels into projections of complex 3D models in the fashion of hand-made illustrations. The real-time label layout algorithms proposed in the paper balance a number of conflicting requirements such as unambiguity, readability, aesthetic considerations and frame-coherency.

Motif definition and classification to structure non-linear plots and to control the narrative flow in interactive dramas

This paper presents a visual editor which supports authors to define the narrative macrostructure of non-linear interactive dramas. This authoring tool was used to represent Propps narrative macrostructure of Russian fairy tales in non-linear plot graphs. Moreover, Propps thorough characterization of basic narrative constituents by explanations, discussions and examples of their different realizations in his corpus is utilized to construct an automatic classification model. A semi-automatic classification supports (i) authors to associate new scenes with basic narrative constituents and (ii) players to control the narrative flow in the story engine. For the latter task, the selection of an appropriate plot element and behavioral pattern within the dialog model in response to player interactions is controlled by similarities between stimuli and known realizations of basic narrative constituents or behavioral patterns. This approach tackles the main challenge of interactive drama — to balance interactivity and storyness.

A spreading activation approach to text illustration

In this paper we present a new approach to implement intelligent multimedia interfaces. Its central elements are a media-independent formal representation of the presented knowledge and media-specific realization statements. Reference hypotheses for media objects are established automatically. Subsequently, the reference hypotheses are validated and weighted by a spreading activation algorithm. Moreover, the spreading activation algorithm determines those entities of the formal representation which are relevant considering an interactively modified multimedia presentation. Finally, the information on the relevance and on the co-reference of media objects are exploited to guarantee the coherency of the multimedia presentation.This paper is focused on the automatic generation of illustrations which are adjusted to the content of interactively selected text segments. Initial results of two application systems, the TEXTILLUSTRATOR and VISDOK, are presented.

Correlating Text and Images: Concept and Evaluation

This paper presents the concept and an evaluation of a novel approach to support students to understand complex spatial relations and to learn unknown terms of a domain-specific terminology with coordinated textual descriptions and illustrations. Our approach transforms user interactions into queries to an information retrieval system. By selecting text segments or by adjusting the view to interesting domain objects, learners can request additional contextual information. Therefore, the system uses pre-computed multi-level representations of the content of explanatory text and of views on 3D models to suggest textual descriptions or views on 3D objects that might support the current learning task. Our experimental application is evaluated by a user study that analyzes (i) similarity measures that are used by the information retrieval system to coordinate the content of descriptive texts and computer-generated illustrations and (ii) the impact of the individual components of these measures. Our study revealed that the retrieved results match the preferences of the users. Furthermore, the statistical analysis suggests a rough value to cut-off retrieval results according to their relevancy.

Figure captions in visual interfaces

We present a general concept for the enhancement of visual interfaces with automatic figure captions describing a visualization. The incorporation of figure captions in interactive systems raises some fundamentally new questions as these images are exposed to changes. The dynamic aspects to be considered include the update and customization of figure captions.We employ figure captions not only for the description of images but also for their modification leading to the introduction of interactive figure captions. A general architecture is developed and comprehensively described referring to two application domains: medical illustrations and geographic maps.