High Quality Rendering

High quality images are necessary if one wants to produce NPR renderings, in particular, for print and high-resolution displays. During my research on line rendering and pen-and-ink NPR I worked on several techniques that produce such high quality images. These techniques generate vector images as output of the NPR rendering algorithms wherever possible to avoid the pixel artifacts commonly seen when regular images are displayed on high-resolution displays or media. An example image embedded as an SVG file is shown below:

By using vector graphics rendering one can not only render line drawings but shading (such as Gooch shading) as well. This makes it possible to render complete illustrations directly as vector images so that they can be used at high-resolutions in print or other media.

Vector graphics are quite different from pixel images and pose some very interesting challenges. For example, the surface shading technique mentioned above takes the technology to the limit as most PDF viewers do not yet support such modes at all or do not yet show them nicely anti-aliased. In addition, very detailed vector graphics can produce fairly large files and may take considerable time to render, even on fast machines, because all the fine detail is contained in a file. Thus, I am interested in approaching some research challenges left to solve such as, among others, how to achieve progressive encoding or how graphics hardware may be used to speed up the rendering process.

Some example tools I worked on that produce non-photorealistic vector renditions can be found on the OpenNPAR page.

Publications

• Ross Maciejewski, Tobias Isenberg, William M. Andrews, David S. Ebert, Mario Costa Sousa, and Wei Chen. Measuring Stipple Aesthetics in Hand-Drawn and Computer-Generated Images. Computer Graphics & Applications, 28(2):62–74, March/April 2008. (PDF, 4205075 bytes) (doi:10.1109/MCG.2008.35)
• Ross Maciejewski, Tobias Isenberg, William M. Andrews, David S. Ebert, and Mario Costa Sousa. Aesthetics of Hand-Drawn vs. Computer-Generated Stippling. In Douglas W. Cunningham, Gary Meyer, László Neumann, Alan Dunning, and Raquel Paricio, editors, Proceedings of Computational Aesthetics in Graphics, Visualization, and Imaging 2007 (CAe 2007, June 20–22, 2007, Banff, Alberta, Canada), Eurographics Workshop Series, pages 53–56, Aire-la-Ville, Switzerland, 2007. Eurographics Association. (PDF, 1400625 bytes) (doi:10.2312/COMPAESTH/COMPAESTH07/053-056)
• Tobias Isenberg, Petra Neumann, Sheelagh Carpendale, Mario Costa Sousa, and Joaquim A. Jorge. Aesthetics of Hand-Drawn and Computer-Generated Illustrations. In Bruce Gooch, László Neumann, Werner Purgathofer, and Mateu Sbert Casasayas, editors, Dagstuhl Seminar 06221 on Computational Aesthetics in Graphics, Visualization and Imaging. 2006. Also see the paper at NPAR 2006.
• Tobias Isenberg, Petra Neumann, Sheelagh Carpendale, Mario Costa Sousa, and Joaquim A. Jorge. Non-Photorealistic Rendering in Context: An Observational Study. In Doug DeCarlo and Lee Markosian, editors, Proceedings of the Fourth International Symposium on Non-Photorealistic Animation and Rendering (NPAR 2006, June 5–7, 2006, Annecy, France), pages 115–126, New York, 2006. ACM Press. Also see the presentation at Dagstuhl Seminar 06221. (PDF, 37376205 bytes) (doi:10.1145/1124728.1124747)
• Tobias Isenberg, Angela Brennecke, Mario Costa Sousa, and Sheelagh Carpendale. Beyond Pixels: Illustration with Vector Graphics. Technical Report 2005-804-35, Department of Computer Science, University of Calgary, Canada, December 2005. (PDF, 6424414 bytes) (doi:1880/45776)
• Tobias Isenberg, M. Sheelagh T. Carpendale, and Mario Costa Sousa. Breaking the Pixel Barrier. In László Neumann, Mateu Sbert Casasayas, Bruce Gooch, and Werner Purgathofer, editors, Proceedings of the First Eurographics Workshop on Computational Aesthetics in Graphics, Visualization and Imaging 2005 (Computational Aesthetics 2005, May 18–20, 2005, Girona, Spain), Eurographics Workshop Series, pages 41–48, Aire-la-Ville, Switzerland, 2005. Eurographics Association. (PDF, 15411674 bytes) (doi:10.2312/COMPAESTH/COMPAESTH05/041-048)
• Tobias Isenberg, Petra Neumann, Sheelagh Carpendale, Mario Costa Sousa, and Joaquim A. Jorge. Non-Photorealistic Rendering in Context: An Observational Study. Technical Report 2005-805-36, Department of Computer Science, University of Calgary, Canada, December 2005. Also see the paper at NPAR 2006 and the presentation at Dagstuhl Seminar 06221. (PDF, 39012237 bytes) (doi:1880/45777)
• Johannes Zander, Tobias Isenberg, Stefan Schlechtweg, and Thomas Strothotte. Creating High Quality Hatching Illustrations. Technical Report, FIN Preprint Series 12/2004, Department of Computer Science, Otto-von-Guericke University of Magdeburg, Germany, 2004. Also see the paper at Eurographics 2004. (PDF, 6642264 bytes)
• Johannes Zander, Tobias Isenberg, Stefan Schlechtweg, and Thomas Strothotte. High Quality Hatching. Computer Graphics Forum (Proceedings of Eurographics 2004, August 30–September 3, 2004, Grenoble, France), 23(3):421–430, September 2004. Also see the technical report which contains additional details and examples. (PDF, 5110034 bytes) (doi:10.1111/j.1467-8659.2004.00773.x)
• Henry Sonnet, Tobias Isenberg, Jana Dittmann, and Thomas Strothotte. Illustration Watermarks for Vector Graphics. In Jon Rokne, Reinhard Klein, and Wenping Wang, editors, Proceedings of the 11^th Pacific Conference on Computer Graphics and Applications, Pacific Graphics 2003 (PG 2003, October 8–10, Canmore, Alberta, Canada), pages 73–82, Los Alamitos, CA, 2003. IEEE Computer Society, IEEE. (PDF, 1545648 bytes) (doi:10.1109/PCCGA.2003.1238249)

Techniques that produce vector images

• Petra Neumann, Tobias Isenberg, and Sheelagh Carpendale. NPR Lenses: Interactive Tools for Non-Photorealistic Line Drawings. In Andreas Butz, Brian Fisher, Antonio Krüger, Patrick Olivier, and Shigeru Owada, editors, Proceedings of the 7^th International Symposium on Smart Graphics (SG 2007, June 25–27, 2007, Kyoto, Japan), volume 4569 of Lecture Notes in Computer Science, pages 10–22, Berlin, Heidelberg, 2007. Springer-Verlag. (PDF, 2414698 bytes) (doi:10.1007/978-3-540-73214-3_2)
• Tobias Isenberg and Angela Brennecke. G-Strokes: A Concept for Simplifying Line Stylization. Computers & Graphics, 30(5):754–766, October 2006. (PDF, 3584265 bytes) (doi:10.1016/j.cag.2006.07.006)
• Petra Neumann, Tobias Isenberg, and Sheelagh Carpendale. NPR Lenses: Local Effect Control for Non-Photorealistic Line Drawings. In Doug DeCarlo and Lee Markosian, editors, Poster Presentations of the Fourth International Symposium on Non-Photorealistic Animation and Rendering (NPAR 2006, June 5–7, 2006, Annecy, France), 2006. Also see the paper at Smart Graphics 2007 and the technical report. (PDF, 658412 bytes)
• Tobias Isenberg and Angela Brennecke. G-Strokes: A Concept for Simplifying Line Stylization. Technical Report 2005-780-11, Department of Computer Science, University of Calgary, Canada, April 2005. Also see the article in Computers & Graphics. (PDF, 1909506 bytes) (doi:1880/46353)
• Petra Neumann, Tobias Isenberg, M. Sheelagh T. Carpendale, and Thomas Strothotte. Expressive Distortion of Strokes and 3D Meshes. Technical Report 2005-776-07, Department of Computer Science, University of Calgary, Canada, March 2005. Also see the paper at Smart Graphics 2007 and the poster at NPAR 2006. (PDF, 2477272 bytes) (doi:1880/45771)
• Tobias Isenberg, Nick Halper, and Thomas Strothotte. Stylizing Silhouettes at Interactive Rates: From Silhouette Edges to Silhouette Strokes. Computer Graphics Forum (Proceedings of Eurographics 2002, September 2–6, 2002, Saarbrücken, Germany), 21(3):249–258, September 2002. (PDF, 829789 bytes) (doi:10.1111/1467-8659.00584)
• Tobias Isenberg, Maic Masuch, and Thomas Strothotte. 3D Illustrative Effects for Animating Line Drawings. In Proceedings of the IEEE International Conference on Information Visualisation (IV 2000, July 19–21, 2000, London, England, UK), pages 413–418, Los Alamitos, California, 2000. IEEE Computer Society, The Institute of Electrical and Electronics Engineers, Inc. (PDF, 1214046 bytes) (doi:10.1109/IV.2000.859790)
• Tobias Isenberg. Visualisierung von Modellierungsentscheidungen und Unsicherheiten in virtuellen Rekonstruktionen [Visualization of Modeling Decisions and Uncertainties in Virtual Reconstructions]. Unpublished report at the Department of Simulation and Graphics, Otto-von-Guericke University Magdeburg, Germany, 1999. In German, also see paper at CGI 1999. (PDF, 2587313 bytes)
• Tobias Isenberg. Visualisierungseffekte in liniengraphischen Animationen und Stillbildern [Visualization Effects in Animated and Single-Frame Line Drawings]. Diplom thesis at the department of simulation and graphics, Otto-von-Guericke University Magdeburg, Germany, 1999. In German, also see paper at IV 2000. (PDF, 6914065 bytes)
• Thomas Strothotte, Maic Masuch, and Tobias Isenberg. Visualizing Knowledge about Virtual Reconstructions of Ancient Architecture. In Proceedings Computer Graphics International 1999 (CGI 99, June 7–11, 1999, Canmore, Alberta, Canada), pages 36–43, Los Alamitos, CA, 1999. The Computer Graphics Society, IEEE Computer Society. (PDF, 1904742 bytes) (doi:10.1109/CGI.1999.777901)