.
A Developer's Guide to Silhouette Algorithms for Polygonal Models
Tobias Isenberg, Bert Freudenberg, Nick Halper, Stefan Schlechtweg, Thomas Strothotte.
IEEE Computer Graphics and Applications, Vol. 23, No. 4, pp. 28--37, July/August,
2003. [BibTeX]
Game Programming Gems 4
Bert Freudenberg, Maic Masuch, Thomas Strothotte.
Andrew Kirmse, Real-Time Halftoning: Fast and Simple Stylized Shading, pp. 443--440, Charles River Media,
2004. [BibTeX]
Non-Photorealistic Shading in an Educational Game Engine
Bert Freudenberg, Maic Masuch.
Production Process of 3D Computer Graphics Applications - Structures, Roles and Tools, Snowbird, Utah, USA, June 1 - 4,
2002. [BibTeX]
OPENNPAR: A System for Developing, Programming, and Designing Non-Photorealistic Animation and Rendering
Nick Halper, Tobias Isenberg, Felix Ritter, Bert Freudenberg, Oscar E. Meruvia Pastor, Stefan Schlechtweg, Thomas Strothotte.
11th Pacific Conference on Computer Graphics and Applications (PG'03), pp. 424, Canmore, Canada,
2003. [BibTeX]
Real-Time Animated Stippling
Oscar E. Meruvia Pastor, Bert Freudenberg, Thomas Strothotte.
IEEE Computer Graphics and Applications, Vol. 23, No. 4, pp. 62-68,
2003. [BibTeX]
Real-Time Halftoning: A Primitive For Non-Photorealistic Shading
Bert Freudenberg, Maic Masuch, Thomas Strothotte.
Eurographics Workshop on Rendering, pp. 1–4,
2002. [BibTeX]
Real-Time Stroke Textures
Author(s): Bert Freudenberg.
Misc: Technical Sketch presented at SIGGRAPH 2001,
2001.
[BibTeX] 
Abstract:
Shading in line drawings is expressed by varying the
stroke width or density of strokes covering an object's
surface. In their pioneering work, Winkenbach and
Salesin introduced the concept of "prioritized stroke
textures" to the emerging field of non-photorealistic
rendering1. Despite the advances in processing power
in the years since then, the sheer number of lines to
draw prevents this method from running in real-time. A
real-time approach for hatching was presented by Lake
et al.2, which chooses from a set of textures based on
the brightness at vertices, subdividing polygons if
necessary. However, the method is very CPU-heavy
and requires many polygons.
Real-Time Stroke-Based Halftoning
Bert Freudenberg.
Otto-von-Guericke-Universität, Magdeburg,
2003. [BibTeX]
Subdivision for Line Drawings
Bert Freudenberg.
2001. [BibTeX]
The Computer-Visualistik-Raum: veritable and inexpensive presentation of a virtual reconstruction
Bert Freudenberg, Maic Masuch, Niklas Röber, Thomas Strothotte.
Proceedings of the 2001 conference on Virtual reality, archeology, and cultural heritage (VAST '01), pp. 97--102,
2001. [BibTeX]