Interactive Stylized Silhouettes

In Eurographics 2002:
 

Stylizing Silhouettes at Interactive Rates: From Silhouette Edges to Silhouette Strokes

Tobias Isenberg and Nick Halper and Thomas Strothotte

 

Abstract

A way to create effective stylized line drawings is to draw strokes that start and stop at visible portions along the silhouette of an object to be portrayed. In computer graphics to date, algorithms to extract silhouette edges are many, although putting these edges into a form such that stylized strokes may be applied to them has not been greatly covered, so that existing methods are either time-consuming or presented vaguely. In this paper, we introduce an algorithm that takes a set of silhouette edges originating from polygonal meshes and efficiently computes the visible parts of the edges before connecting them to form long smooth silhouette strokes to which stylization algorithms may be effectively applied. Features of our algorithm that gain efficiency and accuracy over existing methods is that we directly exploit the analytic connectivity information of the mesh in combination with the available z-buffer information during rendering, and filter artifacts in connected edges during the process to improve the visual quality of strokes after stylization.

Reference

Tobias Isenberg, Nick Halper, and Thomas Strothotte. Stylizing Silhouettes at Interactive Rates: From Silhouette Edges to Silhouette Strokes. Computer Graphics Forum (Proceedings of Eurographics), 21(3):249-258, September 2002. (PDF)

Videos

Click on the images to start an AVI (Intel Indeo format).  Each video is approximately 300k to 4MB in size. Note that these silhouettes are computed at interactive rates (see timing measurements in paper) to give a series of connected visible edges on which the stylizations are applied.

 
Cartoon Rabbit with oilpaint texture and depth emphasis applied to silhouette.
As with left image, but additional waviness applied.

 

Simple scene with pencil texture
With chalk and depth emphasis
Pencil texture with waviness added along the stroke

 

A knot rendered with a furry texture and depth emphasis

 

 


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© 2002-2004 Nick Halper  [nick@isg.cs.uni-magdeburg.de ] and Tobias Isenberg