Most illustrative techniques used in non-photorealistic rendering to date apply a rendering style to objects or a scene and alter the appearance of this style by employing illumination or depth cueing. However for generating high quality illustrations this approach relies almost entirely on smart placement of light sources. We introduce the concept of illustrative effects to describe the workings of illustrative techniques that rely on spatial location rather than just illumination or depth. Although the rendering style is still object-dependent, this technique allows us to visualize or emphasize parts of objects or the whole scene without being limited by the scene's object decomposition. The approach also enforces the decoupling of the model and its animation from the visualization task. We demonstrate our approach using a sample collection of illustrative effects applied to line drawings. A uniform set of tools to manipulate these effects is provided.
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