Structuring and layering contour drawings of organic shapes

Even Entem, Amal Dev Parakkat, Marie-Paule Cani, Loïc Barthe
2018 Proceedings of the Joint Symposium on Computational Aesthetics and Sketch-Based Interfaces and Modeling and Non-Photorealistic Animation and Rendering - Expressive '18  
Figure 1 : An illustration of the steps of our automatic structuring and layering system. (a) The input drawing. (b) Structure analysis and part-completion estimate the constituent parts and their layering. The arrows represent the partial depth ordering ("over" relation). (c) Manipulation of the depth ordering as desired (top), followed by the union of these elements composed with the original internal contours to produce a new drawing (bottom). ABSTRACT Complex vector drawings serve as
more » ... ent and expressive visual representations, but they remain difficult to edit or manipulate. For clean-line vector drawings of smooth organic shapes, we describe a method to automatically extract a layered structure for the drawn object from the current or nearby viewpoints. The layers correspond to salient regions of the drawing, which are often naturally associated to 'parts' of the underlying shape. We present a method that automatically extracts salient structure, organized as parts with relative depth orderings, from clean-line vector drawings of smooth organic shapes. Our method handles drawings that contain complex internal contours with T-junctions indicative of occlusions, as well as internal curves that may either be expressive strokes or substructures. To extract the structure, we introduce a new partaware metric for complex 2D drawings, the radial variation metric, which is used to identify salient sub-parts. These sub-parts are then considered in a priority-ordered fashion, which enables us to identify and recursively process new shape parts while keeping track of Permission to make digital their relative depth ordering. The output is represented in terms of scalable vector graphics layers, thereby enabling meaningful editing and manipulation. We evaluate the method on multiple input drawings and show that the structure we compute is convenient for subsequent posing and animation from nearby viewpoints.
doi:10.1145/3229147.3229155 dblp:conf/npar/EntemPCB18 fatcat:zhwkfifymzcfnp2ff5ttuh5jmy