Locally Controllable Stylized Shading

Hideki Todo (Univ. Tokyo), Ken Anjyo (OLM Digital, Inc.),
William Baxter (OLM Digital, Inc.), Takeo Igarashi (Univ. Tokyo)



[ Abstract ] [ Demo ] [ Publication ] [ Link ]


Abstract

Recent progress in non-photorealistic rendering (NPR) has led to many stylized shading techniques that efficiently convey visual information about the objects depicted. Another crucial goal of NPR is to give artists simple and direct ways to express the abstract ideas born of their imaginations. In particular, the ability to add intentional, but often unrealistic, shading effects is indispensable for many applications. We propose a set of simple stylized shading algorithms that allow the user to freely add localized light and shade to a model in a manner that is consistent and seamlessly integrated with conventional lighting techniques. The algorithms provide an intuitive, direct manipulation method based on a paint-brush metaphor, to control and edit the light and shade locally as desired. Our prototype system demonstrates how our method can enhance both the quality and range of applicability of conventional stylized shading for offline animation and interactive applications.

Demo

System Overview (27MB, with sound)


face_comparison
Figure: Comparison of conventional toon shading (top) with our result (bottom)
Edits were made at the three key frames indicated: (left) added shaded area below left eye for expressive impact, (middle) added shaded area below nose to emphasize three-dimensionality, and (right) added dark area lower lip and neck. These local edits integrate seamlessly with the global lighting, animate smoothly, and require no modification to the external lighting setup.

[Example 1]
Editing shade and highlights.
The animation (left) created using a standard cartoon shader was modified (right) using our techniques. First the excessive highlight on the forehead was removed using the intensity brush, and then the boundary brush was used to create a light region around the chin, which was otherwise invisible.

[Example 2]
Modifying shading with gradations.
Here our prototype system has been used to make a directional lighting setup appear to be a more dramatic back-lit situation.

[Example 3]
Editing light and shade on a highly deforming object.
Using the intensity brush, we edited the light and/or dark areas on the deforming cape under rapidly changing lighting conditions.

Publication


"Locally Controllable Stylized Shading"
Hideki Todo, Ken-ichi Anjyo, William Baxter, Takeo Igarashi
ACM Transactions on Graphics Volume 26, Issue 3, Article No.17
(SIGGRAPH2007, August 5-9 2007, San Diego, USA)
PDF

Link


OLM Digital,Inc

Igarashi Lab.
(University of Tokyo)

© OLM Digital, Inc. 2007 All Rights Reserved.
May.2.2007
Last modified : September.3.2007