Analytic drawing of 3D scaffolds

Abstract

Figure 1: Our analytic drawing tool infers 3D scaffolds of linear segments (a) from sketched strokes. 3D feature curves can then be sketched by deriving position and tangent constraints from the scaffold (b). After fixing the viewpoint and adding image-space silhouette curves (c), we apply traditional hand-rendering techniques [Robertson 2003] to create a production design drawing of the espresso machine (d). AbstractWe describe a novel approach to inferring 3D curves from perspective drawings in an interactive design tool. Our methods are based on a traditional design drawing style known as analytic drawing, which supports precise image-space construction of a linear 3D scaffold. This scaffold in turn acts as a set of visual constraints for sketching 3D curves. We implement analytic drawing techniques in a pure-inference sketching interface which supports both singleand multi-view incremental construction of complex scaffolds and curve networks. A new representation of 3D drawings is proposed, and useful interactive drawing aids are described. Novel techniques are presented for deriving constraints from single-view sketches drawn relative to the current 3D scaffold, and then inferring 3D line and curve geometry which satisfies these constraints. The resulting analytic drawing tool allows 3D drawings to be constructed using exactly the same strokes as one would make on paper.

3D-look shading from contours and hatching strokes

“…Furthermore, for a future version of our implemented system, we are investigating an improved user interface that assists users to draw multiple hatching strokes quickly. Finally, we believe that there is much room for incorporating our detailed normal controls using hatching strokes into sketch-based modeling methods that have focused on rough 3D geometry and normal estimations [8,11,12,14,15,19,20,27]. (c) normal field generated without hatching stroke normals; (d) normal field generated by our hatching-based method; (e) rendering of (c); (f) rendering of (d).…”

“…This system constructs a 3D model by combining parts selected from a database by means of shadow guidance. More recently, several approaches have been proposed for directly obtaining a comprehensive 3D model using sketching strokes from a single view [14][15][16][17][18][19][20][21]. These methods provide artists with a more familiar workflow from 2D to 3D modeling.…”

An algorithm for estimating surface normal from its boundary curves

“…lyzing a newly drawn 2D sketch and defining its relationships to an existing sketch. Schmidt et al [3] implemented a mathema cal model by analyzing the sketching process and reconstructing a 2D sketc The paper by Schaefer et al [7] is representative of the studies presenting surface modeling based on thus constructed. This paper presented a method of improving a model towards satisfying C1 continuity after gener lar patches from the adjacent curves within the vision method.…”

“…In parallel to this stream of research, there has been considerable research focused on the methodologies for the presented by Bae et al [1] is a system for constructing 3D curve networks allowing direct JustDrawIt!, Grimm and Joshi [2] presented a 2D-to-3D conversion method by an lyzing a newly drawn 2D sketch and defining its relationships to an existing sketch. Schmidt et al [3] implemented a mathema cal model by analyzing the sketching process and reconstructing a 2D sketch as a 3D sketch.…”

“…Computeraided design (CAD), notwithstanding its enormous progress from the initial-phase Boolean operations on basic diagrams to a variety of geometric operations, still requires a lengthy training period and a high degree of technical expertise. Recent years have seen the emergence of novel modeling technologies for building 3D curve networks from designers' two-dimensional (2D) sketches in an effort to lower the hurdle for using professional 3D modeling tools [1][2][3]. Such modeling methods are widely used for concept design in the initial phases of design because they facilitate the intuitive expression of the designer's ideas and allow room for additional creative elements.…”