An Invitation to Discuss Computer Depiction
Author(s): Frédo Durand.
Proceedings: 2nd International Symposium on Non-Photorealistic Animation and Rendering (NPAR'02), Annecy, France, June 3-5,
2002.
[BibTeX] 
Abstract:
This paper draws from art history and perception to place
computer depiction in the broader context of picture production.
It highlights the often underestimated complexity of
the interactions between features in the picture and features
of the represented scene. Depiction is not always a unidirectional
projection from a 3D scene to a 2D picture, but involves
much feedback and influence from the picture space
to the object space. Depiction can be seen as a pre-existing
3D reality projected onto 2D, but also as a 2D pictorial representation
that is superficially compatible with an hypothetic
3D scene. We show that depiction is essentially an optimization
problem, producing the best picture given goals and constraints.
We introduce a classification of basic depiction techniques
based on four kinds of issue. The spatial system deals with
the mapping of spatial properties between 3D and 2D (including,
but not restricted to, perspective projection). The
primitive system deals with the dimensionality and mappings
between picture primitives and scene primitives. Attributes
deal with the assignment of visual properties such as colors,
texture, or thickness. Finally, marks are the physical implementations
of the picture (e.g. brush strokes, mosaic cells).
A distinction is introduced between interaction and picturegeneration
methods, and techniques are then organized depending
on the dimensionality of the inputs and outputs.