Lehrveranstaltungsinhalt aus - Institute for Computer Graphics and ...

Chapter 0
Introduction
0.1 Using Cyber-Cities as an Introduction
We introduce the subject of “digital processing of visual information”, also denoted as “digital
image processing” and “computer graphics”. We introduce the subject by means of one particular
application, namely 3D computer modelling of our cities. This is part of the wider topic of the so
called “virtual habitat”. “Modelling cities”, what do we mean by that? The example in Slide 0.7
shows a traditional representation of a city, in this particular example the “Eisene Tor” in Graz.
In two dimensions we see the streetcar tracks, we see the Mariensäule, buildings and vegetation.
This is the status quo of current urban 2-D computer graphics.
The new approach is to represent this in three dimension as shown in Slide 0.8. The two dimensional
map of the city is augmented to include the third dimension, thus the elevations, and in
order to render, represent or visualise the city we add photographic texture to create as realistic
a model of the city as possible. Once we have that we can stroll through the city, we can inspect
the buildings, we can read the signs and derive from them what’s inside the buildings.
The creation of the model for this city is a subject of “image processing”. The rendering of the
model is the subject of “computer graphics”. These two belong together and constitute a field
denoted as “digital processing of visual information”.
The most sophisticated recent modelling of a city was archieved of a section of Philadelphia. This
employed a software called “Microstation” and was done by hand with great detail. In this case
this detail includes vegetation, the virtual trees, waterfountains and people. I am attempting
here to illustrate the concepts of “computer graphics” and “image processing” by talking about
Cyber-Cities, namely how to create them from sensor data and how to visualise them. And this
is the subject of this introduction.
0.2 Introducing the Lecturer
Before we go into the material, permit me to introduce myself. I have roots both in Graz and
in Boulder (Colorado, USA). My affiliations are since 1992 with the Technische Universität Graz,
where I am a Professor of Computer Vision and Graphics. But I am also affiliated with a company
in the United States since 1985 called Vexcel Corporation. In both places, the Vexcel Corporation
and the University, cyber-cities play a role in the daily work. Vexcel Corporation in the US
operates in four technical fields:
1. It builds systems to process radar images
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