Semantic-based Interactive Shape Analysis and Manipulation

The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


Title: "Semantic-based Interactive Shape Analysis and Manipulation"

By

Mr. Youyi Zheng


Abstract

Geometric modeling is a fundamental problem in computer graphics. The 
continuous growth of 3{D} models in public repositories has shifted 
researchers' focus from computing local, low-level geometry features such 
as curvatures and textures to high-level semantic information such as 
shape parts information and shape structural characteristics (symmetry, 
parallelism, etc.). However, automatically computing these semantic 
information is essentially an ill-posed problem due to the ambiguities in 
the definition of shape semantics.

This thesis focuses on developing interactive approaches to aid the shape 
analysis process. We leverage the user assistance to exploit shape 
semantics, and to respect and preserve them during manipulation. In 
particular, this thesis aims at advancing the state-of-the-art interactive 
techniques in two specific geometric applications: shape segmentation and 
shape manipulation.

First, we introduce two interactive tools for shape segmentation, which we 
call cross-boundary brushes and dot scissor. Both tools offer very simple 
and easy-to-use user interfaces that operate at interactive rates. In 
contrast to the state-of-the-art interactive segmentation tools, our tools 
allow the user to cut out meaningful and functional components using only 
a single mouse stroke or click near boundary regions in most cases, making 
them very convenient to use. We adopt the concept of isolines of harmonic 
fields as cutting boundaries in designing both tools. We show that the 
propagation properties and the differentiating power of the harmonic 
fields allow effective computation of shape semantic boundaries for 
segmentation purpose.

Second, we developed an editing framework that first extracts the shape 
structural features and preserves them during user manipulation. In 
contrast to traditional shape editing framework, the system operates at 
the component level and takes shape structural characteristics such as 
inter-relations among semantic components as modeling constraints, 
enabling an effective structure-preserving editing tool. We show that user 
assistance is essential in accurately revealing the complex shape 
structures. We use a semi-automatic shape segmentation process as a prior 
step to facilitate the analysis of shape structures and inter-relations, 
and show that these shape analysis results play an important role in 
preserving the shape global features during user manipulation.


Date:			Wednesday, 3 August 2011

Time:			2:00pm – 4:00pm

Venue:			Room 5508
 			Lifts 25/26

Chairman:		Prof. Andrew Poon (ECE)

Committee Members:	Prof. Chiew-Lan Tai (Supervisor)
 			Prof. Huamin Qu
 			Prof. Long Quan
                      	Prof. Kai Tang (MECH)
                         Prof. Pheng-Ann Heng (Comp. Sci. & Engg., CUHK)


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