Tuning rendered line-drawings

Normally rendered images are the polished output of rendering software and are, by definiton, "perfect". However, as we think about rendering abstractions of the underlying models, rather than photorealistic images, it becomes evident that user involvement is necessary to tune rendered images to his or her satisfaction. In this paper we outline methods to tune rendered images. We concentrate on line-drawings, as these are most readily edited to make the modelled objects appear more abstract. Rather than having users edit individual lines, our emphasis lies on studying, what users really want to achieve, and how we can support them more directly to attain these effects. This emphasis is used to guide the design of the user-interface to the system for tuning line-drawings. We present a tool which allows high-level intent-based interaction to generate line-drawings from rendered 3D-models. Included in the system are editing facilities to fine-tune and thereby individualizing line-drawings. High-level interaction draws on statistical methods to distribute lines over the rendered image. We show how the interaction can be improved if information about the model is available to the image editor