A 3D Model Search Engine (Thesis)

Abstract:

This thesis describes an online search engine for 3D models, focusing
on query interfaces and their corresponding model/query
representations and matching methods.

A large number of 3D models has already been created, many of which
are freely available on the web. Because of the time and effort
involved in creating a high-quality 3D model, considerable resources
could be saved if these models could be re-used. However, finding the
model you need is not easy, since most online models are scattered
across the web, on repository sites, project sites, and personal
homepages.

To make these models more accessible, we have developed a prototype 3D
model search engine. This project serves as a test bed for new
methods in web crawling, query interfaces, and matching of 3D models.
This thesis focuses on query interfaces and their accompanying
matching methods. We investigated query interfaces based on text
keywords, 3D shape, 2D shape, and some combinations.

By testing matching methods that use text, 3D shape, and 2D shape, we
found that the 3D shape matching method outperforms our text matching
method for our application domain, due to the insufficient text
annotation of 3D models on the web. Furthermore, classification
performance was improved by combining the 3D shape- and text-based
matching methods. The results of a user study also suggest that text
can combine with shape to make queries more effective.

We compared shape matching methods based on matching multiple 2D
projections of a 3D model and found that from a set of side, corner
and edge projections, the combination of side and corner projections
produced the best results. However, these results were still worse
than those of the 3D shape matching method.

We present a 2D structural interface and accompanying matching method
that produces better classifications than image matching for certain
types of objects.

Our prototype search engine has been used extensively across the world
(in 18 months, almost 300,000 queries have been processed from more
than 100 countries) and has proven to be useful (models have been
downloaded over 50,000 times, and almost 30% of all visitors per day
are returning users).