Where do people draw lines?

Abstract

This paper presents the results of a study in which artists made line drawings intended to convey specific 3D shapes. The study was designed so that drawings could be registered with rendered images of 3D models, supporting an analysis of how well the locations of the artists' lines correlate with other artists', with current computer graphics line definitions, and with the underlying differential properties of the 3D surface. Lines drawn by artists in this study largely overlapped one another (75% are within 1mm of another line), particularly along the occluding contours of the object. Most lines that do not overlap contours overlap large gradients of the image intensity, and correlate strongly with predictions made by recent line drawing algorithms in computer graphics. 14% were not well described by any of the local properties considered in this study. The result of our work is a publicly available data set of aligned drawings, an analysis of where lines appear in that data set based on local properties of 3D models, and algorithms to predict where artists will draw lines for new scenes.

3D-look shading from contours and hatching strokes

“…Contour hatching consist of hatch marks that pictorially express the local curvatures of the surface underneath because they adhere to the surface of local curves [1,3]. Therefore, we assume that each hatching stroke is sufficiently short to approximate the contacting arc of a circle that osculates the local curve at the stroke center P, as indicated in Fig.…”

“…The principles of 'how artists depict 3D shapes with lines' have been intensively studied in the literature on stylized and nonphotorealistic renderings [1][2][3]. The overall shape of a 3D object is depicted with contours such as silhouette contours and feature contours related to geometric ridges and valleys.…”

Customizable Strokes for Localized Stylization of View-Dependent Lines Extracted from 3D Models

“…As stated in a recent study [2], most of the lines drawn by artist to convey 3D shape can be explained by some of the most commonly-known line extraction algorithms. However, artists often make global decisions such as the omission of implicit lines or stylistic decisions which tend to depart from realism.…”

Efficient and robust 3D line drawings using difference-of-Gaussian

“…Based on a parallel method to compute curvatures and their derivatives on deforming objects with strong temporal coherence, Kalogerakis et al [16] proposed an algorithm to compute apparent ridges on dynamic objects. Cole et al [17] conducted a user study on where do artists draw lines to convey 3D shapes. Their results showed that the image edge detector (Canny edges) provides the strongest cues for artists to draw lines, which justifies the research to generalize the image edge detector to object space.…”