Shape Oriented Line Drawing in Real-Time 3DCG

彬彬

1 Introduction

In 2D animation and comics, the line quality of object outlines and

contour lines are often varied to emphasize or exaggerate the shape

of an object. One such technique is to vary the line thickness pending

on the object shape. This technique is often used in sketching

and drawing to give objects a greater sense of depth or dimension.

When using toon rendering to simulate a 2D-esque effect in 3D animation,

techniques that render object outlines of constant thickness,

such as that proposed by [Saito and Takahashi 1990], are popular

due to their ease of application. While existing methods such as

that proposed by [Goodwin et al. 2007] allow for a certain level of

dynamic line thickness through the use of shad-ing, they require

long calculation times and are not suited for real time rendering.

Our study aims to provide a viable real-time 3D toon rendering

technique that creates object outlines with varying thickness. In

particular, our approach changes line thickness at any point based

on the line curvature at that point.

2 Shape Oriented Line Drawing Technique

Detection of Shape Feature Our method aims at emphasizing

line thickness at points of high curvature - where object outlines

are thickest in 2D animation and comics. Points of curvature on

a 3D model correspond to places where the model has either a

concave or convex surface. We calculate the average curvature of

each vertex point on the 3D model using the method proposed by

[Meyer et al. 2002], enabling us to identify the shape feature of any

given vertex on the model.

彬彬

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