Geometric Approximations Towards Free Specular Comic Shading
Holger Winnemöller, Shaun Bangay.
Computer Graphics Forum (EG'02),
2002. [BibTeX]
Implementing Non-photorealistic Rendering Enhancements with Real-Time Performance
Author(s): Holger Winnemöller.
Master Thesis: Computer Science Department, Rhodes University, February,
2002.
[BibTeX]
Abstract:
We describe quality and performance enhancements, which work in real-time, to all well-known Nonphotorealistic
(NPR) rendering styles for use in an interactive context. These include Comic rendering,
Sketch rendering, Hatching and Painterly rendering, but we also attempt and justify a widening of the
established definition of what is considered NPR. In the individual Chapters, we identify typical stylistic
elements of the different NPR styles. We list problems that need to be solved in order to implement the
various renderers. Standard solutions available in the literature are introduced and in all cases extended
and optimised. In particular, we extend the lighting model of the comic renderer to include a specular
component and introduce multiple inter-related but independent geometric approximations which greatly
improve rendering performance. We implement two completely different solutions to random
perturbation sketching, solve temporal coherence issues for coal sketching and find an unexpected use for
3D textures to implement hatch-shading. Textured brushes of painterly rendering are extended by
properties such as stroke-direction and texture, motion, paint capacity, opacity and emission, making
them more flexible and versatile. Brushes are also provided with a minimal amount of intelligence, so that
they can help in maximising screen coverage of brushes. We furthermore devise a completely new NPR
style, which we call super-realistic and show how sample images can be tweened in real-time to produce
an image-based six degree-of-freedom renderer performing at roughly 450 frames per second.
Performance values for our other renderers all lie between 10 and over 400 frames per second on home-
PC hardware, justifying our real-time claim. A large number of sample screen-shots, illustrations and
animations demonstrate the visual fidelity of our rendered images. In essence, we successfully achieve
our attempted goals of increasing the creative, expressive and communicative potential of individual NPR
styles, increasing performance of most of them, adding original and interesting visual qualities, and
exploring new techniques or existing ones in novel ways.
Perceptually-motivated Non-Photorealistic Graphics
Holger Winnemöller.
Northwestern University, Evanston, Illinois, U.S.A.,
2006. [BibTeX]
Real-Time Video Abstraction
Holger Winnemöller, Sven C. Olsen, Bruce Gooch.
ACM Transactions on Graphics (Proc. of SIGGRAPH'06), Vol. 25, No. 3, pp. 1221--1226, July,
2006. [BibTeX]
Rendering optimisations for stylised sketching
Holger Winnemöller, Shaun Bangay.
2nd International Conference on Computer Graphics, Virtual Reality and Visualisation in Africa (AFRIGRAPH'03), pp. 117--122, Cape Town, South Africa,
2003. [BibTeX]