Geoscience Reference
In-Depth Information
Keywords
3D visualization technique • Information visualization • 3D city
model • Ontology • Knowledge base • Human-computer interface
1 Introduction
1.1 Motivation
More and more applications based on 3D virtual city models are used for tasks that
go far beyond the mere visualization of the city objects. These tasks generally require
(1) rich information models that associate urban entities not only with their geomet-
ric properties but also with other types of information related to the city (pollutant
concentration, road labels, historical facts, etc.) and (2) appropriate visualization
techniques. Appropriate techniques rely on a set of criteria such as (1) the data type
to display (2) the tasks that will be performed by the users and (3) the associated
context (level of detail, type of navigation, etc.). But, in the literature related to appli-
cations of 3D city models, the techniques used are too often not explicitly described.
It is thus difficult to select a technique according to precise criteria or to compare
techniques. Furthermore complex tasks can imply visualizing several types of data at
once (e.g. air quality, noise, spatial distribution of pedestrian movement). But a tech-
nique that is efficient when used alone can induce visual incompatibilities when used
in conjunction with others (visual occlusion, etc.). Those incompatibilities have to be
taken in account when selecting visualization techniques.
Therefore, the selection of an effective and efficient visualization technique for
a 3D environment is an important and difficult task. The aim of the work presented
here is precisely to build a knowledge base of visualization techniques that can
serve several purposes, in particular:
• To help a 3D virtual environment designer choosing the most appropriate visu-
alization techniques for the intended users tasks and context (for instance, when
designing a 3D-enabled website to let citizen and professionals explore a new
urban project);
• To help a 3D GIS user select a visualization technique to display a given dataset
in the 3D model. The GIS system must be able to find and propose appropriate
visualization techniques for each dataset, depending on the data types and the
context of use.
1.2 Overview
In this chapter we address the problem of designing and implementing a usable
knowledge base of information visualization techniques in 3D geographic envi-
ronments, in particular in 3D city models. The main results we obtained are:
