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 picture-generation methods, and techniques are then organized depending on the dimensionality of the inputs and outputs.
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