Programmable rendering of line drawing from 3D scenes

Abstract

This article introduces a programmable approach to nonphotorealistic line drawings from 3D models, inspired by programmable shaders in traditional rendering. This approach relies on the assumption generally made in NPR that style attributes (color, thickness, etc.) are chosen depending on generic properties of the scene such as line characteristics or depth discontinuities, etc. We propose a new image creation model where all operations are controlled through user-defined procedures in which the relations between style attributes and scene properties are specified. A view map describing all relevant support lines in the drawing and their topological arrangement is first created from the 3D model so as to ensure the continuity of all scene properties along its edges; a number of style modules operate on this map, by procedurally selecting, chaining, or splitting lines, before creating strokes and assigning drawing attributes. Consistent access to properties of the scene is provided from the different elements of the map that are manipulated throughout the whole process. The resulting drawing system permits flexible control of all elements of drawing style: First, different style modules can be applied to different types of lines in a view; second, the topology and geometry of strokes are entirely controlled from the programmable modules; and third, stroke attributes are assigned procedurally and can be correlated at will with various scene or view properties. We illustrate the components of our system and show how style modules successfully encode stylized visual characteristics that can be applied across a wide range of models.

Free-Hand Sketch Synthesis with Deformable Stroke Models

“…We offer comparisons with two representative DoG-oriented techniques in this paper: the flow-based DoG (FDoG) (Kang et al 2007) that uses edge tangent flow (ETF) to offer edge direction guidance for DoG filtering (originally computed isotropically) and the variable thresholding DoG (XDoG) (Winnemöller 2011) that introduces several additional parameters to the filtering function in order to augment the remit of rendering styles. Quite a large body of the literature (Cole et al 2008;DeCarlo et al 2003;Judd et al 2007;Grabli et al 2010) studied the problem of generating line drawings from 3D models. Yet in contrast to synthesizing from 2D images, 3D models have well-defined structures and boundaries, which make the generation process much easier and less sensitive to noise.…”

Stylized strokes for coherent line drawings

“…Object space hidden lines removal algorithms, as in Refs. [20][21][22], avoid this problem at the price of high computational complexity but may produce many noisy, short segments lacking the spatial and temporal coherence needed for stylization.…”

Depicting stylized materials with vector shade trees

“…Grabli et al [2010] adapt this concept to the stylization of strokes in line drawings and describe programmable shaders to control style attributes such as color, texture and thickness. We adopt a complementary approach by focusing on the stylized depiction of materials, giving control to material attributes like shading and reflections.…”