Browsing by Author "Isenberg, Tobias"

Now showing 1 - 12 of 12
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    Beyond Pixels: Illustration with Vector Graphics
    (2006-02-14) Isenberg, Tobias; Brennecke, Angela; Costa Sousa, Mario; Carpendale, Sheelagh
    This report presents a novel vector rendering pipeline that allows us to easily break the pixel barrier and create high-quality illustrations. Recently, most graphic research has been directed towards rendering pixel images that appear realistic. In contrast, we investigate the generation of vector graphic illustrations using non-photorealistic techniques such as line rendering and Gooch shading. By combining vector output from both shading and line rendering of 3D models we create high-quality illustrations that can directly be used in print reproduction. Our approach uses a vector graphic pipeline that tracks multiple attributes of strokes and uses them for stylization. This allows to have multiple layers of line rendering such as different stroke types or visible and hidden parts of strokes, each treated differently according to specific stylization rules. Using high quality vector graphics (as opposed to pixel renditions) for representing illustration is essential, in particular, in the print reproduction process. Foremost, vector graphics can be reproduced at any desired resolution; they do not suffer from the resolution dependence of pixel images. In addition, only vector graphics can capture fine details accurately while maintaining a reasonable file size. Finally, vector graphics do not need to be half-toned when printed as long as spot colors are used. Even if some layers of the image use, e. g., shading, only those parts of the vector graphic need to be half-toned that actually do not make use of the available spot colors. Thus, we can combine both shading and line layers without compromising print quality.
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    BubbleType: Enabling Text Entry within a Walk-Up Tabletop Installation
    (2008) Hinrichs, Uta; Schmidt, Holly; Isenberg, Tobias; Hancock, Mark; Carpendale, Sheelagh
    We address the issue of enabling text entry for walk-up-and-use interactive tabletop displays located in public spaces. Public tabletop installations are characterized by a diverse target user group, multiperson interaction, and the need for high approachability and intuitiveness. We first define the design constraints of text-entry methods for public tabletop installations such as clear affordances, audience expertise, support of direct-touch interaction, visual appearance, space requirements, multi-user support, and technical simplicity. We then describe an iterative design process that was informed by these constraints and led to the development of two stylus keyboard prototypes—BubbleQWERTY and BubbleCIRCLE—for use in interactive public tabletop installations.
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    Expressive Distortion of Strokes and 3D Meshes
    (2005-03-15) Neumann, Petra; Isenberg, Tobias; Carpendale, Sheelagh
    We introduce methods for applying two-dimensional distortions in a manner that allows us to create three-dimensional variations of stroke-based models and 3D polygonal meshes. These variations can be achieved interactively, supporting the creation of expressive variations of a given 3D model or of strokes generated from it. In order to allow for a seamless integration into existing systems and to enable additional processing of both strokes and meshes, a pipeline approach is taken in both cases. In addition, we discuss the interaction possibilities arising from the interplay between the model orientation and the strokes or the geometry. Finally, to demonstrate the usability of the proposed methods we suggest several application domains.
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    G-Strokes: A Concept for Simplifying Line Stylization
    (2005) Isenberg, Tobias; Brennecke, Angela
    In previous systems, only very few line properties have been used for stylization in line rendering. This is due to a complicated handling and two-way dependency of these properties and the stages of the stylization pipeline. In this paper we propose the concept of G-strokes to efficiently deal with these and many more stroke properties. This new concept allows a much simpler way of representing and handling various line properties and stylization stages. By this we make it easy to enrich the set of line stylization means by adding more properties and stylization stages and, thus, allowing more freedom and creativity for generating expressive line drawings. We show a number of possible G-strokes using both simple and complex examples to demonstrate the power of our approach.
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    Interacting with Stroke-Based Rendering on a Wall Display
    (2007-10-19) Grubert, Jens; Hancock, Mark; Carpendale, Sheelagh; Tse, Edward; Isenberg, Tobias
    We introduce two new interaction techniques for creating and interacting with non-photorealistic images using strokebased rendering. We provide bimanual control of a large interactive canvas through both remote pointing and direct touch. Remote pointing allows people to sit and interact at a distance with an overview of the entire display, while direct-touch interaction provides more precise control. We performed a user study to compare these two techniques in both a controlled setting with constrained tasks and an exploratory setting where participants created their own painting. We found that, although the direct-touch interaction outperformed remote pointing, participants had mixed preferences and did not consistently choose one or the other to create their own painting. Some participants also chose to switch between techniques to achieve different levels of precision and control for different tasks.
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    An Interactive 3D Integration of Parallel Coordinates and Star Glyphs
    (2005-04-29) Fanea, Elena; Carpendale, Sheelagh; Isenberg, Tobias
    Parallel Coordinates are a powerful method for visualizing multidimensional data, however, with large data sets they can become cluttered and difficult to read. On the other hand, a Star Glyph can be used to display either the attributes of a data item or the values across all items for a single attribute. Star Glyphs may readily provide a quick impression; however, since the full data set will require multiple glyphs overall readings are more difficult. We present an interactive integration of the visual representations of Parallel Coordinates and Star Glyphs that utilizes the advantages of both representations to offset the disadvantages they have separately. We discuss the role of uniform and stepped color scales in the visual comparison of non-adjacent items and Star Glyphs. Our visualization provides capabilities for focus-in-context exploration of the data using two types of lenses, and interactions specific to the 3D space.
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    Interactive Stroke-Based NPR using Hand Postures on Large Displays
    (2007-12-10) Grubert, Jens; Carpendale, Sheelagh; Isenberg, Tobias
    We explore the use of hand postures to interact with stroke-based rendering (SBR) on touch-sensitive large displays. In contrast to traditional WIMP interfaces, we allow people to directly engage with and influence a rendering. Our system allows the creation of new stroke primitives as well as provides mechanisms to distribute and then manipulate them on the canvas. We offer a set of natural mappings from hand postures to rendering parameterizations. The resulting system allows an intuitive exploration of SBR without the need for traditional desktop interfaces.
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    Mobile Spatial Tools for Fluid Interaction
    (2007-07-24) Isenberg, Tobias; Nix, Simon; Schwarz, Martin; Miede, Andre; Scott, Stacey D.; Carpendale, Sheelagh
    Fluid interaction techniques are increasingly important for effective work on interactive displays such as tabletops. We introduce mobile spatial tools to support such fluid interaction by affecting the properties of objects in the interface spatially rather than temporally. Our tools allow us to control multiple objects simultaneously using high-level, taskdriven actions without the need for setting low-level properties of objects. We demonstrate a number of specific tools and their application in fluid interaction scenarios.
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    Modeling with Rendering Primitives: An Interactive Non-Photorealistic Canvas
    (2007-02-09) Schwarz, Martin; Isenberg, Tobias; Mason, Katherine; Carpendale, Sheelagh
    We present an interactive approach to non-photorealistic rendering that contrasts with the standard black box character of previous rendering techniques in that observation and interaction take place during rendering. Our technique is based on the idea of approaching non-photorealistic rendering by modeling with rendering primitives. This new approach supports interruption, tweaking, manipulation, and re-direction of the rendering as it develops. While we draw upon computational support for primitive placement to avoid having to painstakingly place each pixel, we limit the computational influence to enable freedom of interaction with the elements. We implement this new paradigm in a stroke-based rendering application using a stack of interaction buffers to store attributes of the primitives during the rendering. By manipulating the data in these buffers we affect the behavior of strokes on the canvas. This allows us to create and adjust images in non-photorealistic styles such as painterly rendering, pointillism, and decorative mosaics at interactive frame rates.
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    Non-Photorealistic Rendering in Context: An Observational Study
    (2006-02-14) Isenberg, Tobias; Neumann, Petra; Carpendale, Sheelagh; Costa Sousa, Mario; Jorge, Joaquim A.
    Pen-and-ink line drawing techniques are frequently used to depict form, tone, and texture in artistic, technical, and scientific illustration. In non-photorealistic rendering (NPR), there has been considerable progress on reproducing traditional pen-and-ink techniques for rendering 3D objects. However, formal evaluation and validation of these NPR images remain an important open research problem. In this paper we present an observational study with three groups of users to examine their understanding and assessment of hand-drawn pen-and-ink illustrations of objects in comparison with NPR renditions of the same 3D objects. The results show that people perceive differences between those two types of illustration but that those that look computer-generated are still highly valued in terms of scientific illustration.
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    Proceedings of the Workshop on Data Exploration for Interactive Surfaces DEXIS 2011
    (2011) Isenberg, Petra; Carpendale, Sheelagh; Hesselmann, Tobias; Isenberg, Tobias; Lee, Bongshin
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    Supporting sandtray therapy on an interactive tabletop
    (ACM, 2010) Hancock, Mark; ten Cate, Thomas; Carpendale, Sheelagh; Isenberg, Tobias
    We present the iterative design of a virtual sandtray application for a tabletop display. The purpose of our prototype is to support sandtray therapy, a form of art therapy typically used for younger clients. A significant aspect of this therapy is the insight gained by the therapist as they observe the client interact with the figurines they use to create a scene in the sandtray. In this manner, the therapist can gain increased understanding of the client's psyche. We worked with three sandtray therapists throughout the evolution of our prototype. We describe the details of the three phases of this design process: initial face-to-face meetings, iterative design and development via distance collaboration, and a final face-to-face feedback session. This process revealed that our prototype was sufficient for therapists to gain insight about a person's psyche through their interactions with the virtual sandtray.