Traditional computer graphics rendering methods (local and global illumination) have attempted to create images that are physically realistic. Non-photorealistic rendering (NPR) is a fairly recent branch of computer graphics that aims to complement these methods, producing scenes in graphical forms and styles traditionally used by artists. By only putting emphasis on certain features, NPR allows for more telling representations of the scenes, infers a greater sense of expressiveness and creative freedom for the artists.

Freestyle is a NPR software developed for a research project dedicated to the study of stylized line drawing rendering from 3D scenes. It intends to be flexible in its design to encompass a whole array of graphical styles, allowing maximum control over the rendered product. Technically, Freestyle uses a programmable paradigm, inspired by shading languages: each artistic form is described by a style module, a series of instructions that transform 3D model features (silhouettes, key edges and intersections, curvature...) into stylized strokes.

The goal of the project is to integrate Freestyle into Blender. The integration will have to focus on adapting Freestyle's source code to Blender's architecture and rendering pipeline. One of the challenges of the project will be to make sure that new expressive styles can easily be created while keeping user interaction and parameter configuration adequate for artists' use.