This paper describes some of the principles of traditional floral ornamental design, and explores ways in which these designs can be created algorithmically. It introduces the idea of “adaptive clip art, ” which encapsulates the rules for creating a specific ornamental pattern. Adaptive clip art can be used to generate patterns that are tailored to fit a particularly shaped region of the plane. If the region is resized or reshaped, the ornament can be automatically regenerated to fill this new area in an appropriate way. Our ornamental patterns are created in two steps: first, the geometry of the pattern is generated as a set of two-dimensional curves and filled boundaries; second, this geometry is rendered in any number of styles. We demonstrate our approach with a variety of floral ornamental designs.

We present an interactive system for creating pen-and-ink-style line drawings from greyscale images in which the strokes of the rendered illustration follow the features of the original image. The user, via new interaction techniques for editing a direction field, specifies an orientation for each region of the image; the computer draws oriented strokes, based on a user-specified set of example strokes, that achieve the same tone as the image via a new algorithm that compares an adaptively-blurred version of the current illustration to the target tone image. By aligning the direction field with surface orientations of the objects in the image, the user can create textures that appear attached to those objects instead of merely conveying their darkness. The result is a more compelling pen-and-ink illustration than was previously possible from 2D reference imagery. CR Categories and Subject Descriptors: I.3.3 [Computer Graphics ]: Picture/Image Generation --- Display algorithms. I.4.3 [...