LEARNING DIGITAL PHOTOGRAMMETRY BY MEANS OF PERSONAL COMPUTERS
Joachim Höhle
Department of Development and Planning
Aalborg University
Denmark
Commission VI, Working Group 2
KEY WORDS:
Training.
ABSTRACT:
Computer-Assisted Learning, Digital Photogrammetry, Computer, Programming, Experience, Education,
The new CAL program “Learning about digital photogrammetry” of Aalborg University is presented. The pedagogical and the
technical concepts of "LDIP" are explained. One theme, the automatic measurement of réseau crosses and fiducial marks, is
presented in more detail. Experiences from the development and the use of the finished parts of "LDIP" are discussed.
KURZFASSUNG:
Das neue CAL Programm "Lernen über digitale Photogrammetrie" der Universitát Aalborg wird vorgestellt. Das dem Programm
zugrunde liegende pádagogische und technische Konzept wird erláutert. Ein Thema, die automatische Messung von Réseau-
Kreuzen und Rahmenmarken, wird ausführlicher behandelt. Erfahrungen von der Entwicklung und von der Benutzung der fertig
gestellten Teile von "LDIP" werden diskutiert.
1. INTRODUCTION
When using digital imagery, the measuring process can be
automated partially. However, the computer-based evaluation
systems are rather sophisticated and the amount of data to be
processed is usually huge (approximately 100 Mb per aerial
image). This means that these systems are expensive, and
they also change quickly. The education in photogrammetry
at university level can neither afford all of the latest imaging
and image evaluation systems nor buy it in considerable
numbers for the training of a large number of students. This
is where computer-assisted learning (CAL) comes into focus.
The equal treatment of students, their active role in the
learning process and their motivation to work with computers
are some of the reasons for CAL gaining in popularity.
Besides mass education, distance learning and self-study are
good reasons for applying CAL. At Aalborg University CAL
has been used since 1987, and various programs for PCs
have been developed and used in the education of land
surveyors (Héhle, J., 1992). Recently, new tools were intro-
duced, for example more advanced personal computers and
storage devices like CD-ROM as well as the Photo-CD
services (Hóhle, J., 1994). By means of these new tools a
new development was started by the author. The program is
called "Learning about Digital Photogrammetry" (“LDIP”) and
it deals with various processes in digital photogrammetry and
image processing. It is the main purpose of this paper to
present this new learning program and to demonstrate the
power of the new possibilities for CAL in photogrammetry.
2. THE LEARNING PROGRAM "LDIP"
“Learning about digital photogrammetry" (“LDIP”) is the title of
a learning program currently under development at Aalborg
University (see fig. 1). The contents will cover themes like
rectification of imagery, generation of perspective views,
correlation, compression techniques, and standard image
formats.
61
EARNING EL
D IG 1] TAL P| HOTOGRAMMETRY
x À 'Computer -Assisted Learning -program
for photogrammetry and image processing
from
Aalborg University
Denmark
©
QUIT
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HELP
ar
=
MAIN MENU INFORMATION
Fig. 1. 'Front page' of the CAL program "LDIP". The fields
with the icons and text on the bottom line are used for
controlling the program.
In the following, the pedagogical and technical concept and
its realization is explained with the example of one theme. The
presented information about this theme shall be described as
well as the exercises to it. First the experiences, when using
the programs at the surveying and mapping education shall
also be mentioned.
2.1 General description of the theme "Automatic mea-
surement by means of correlation"
The evaluation of images starts with the measurement of
fiducial marks. These are well-defined marks at the edges of
the image. The connecting lines between the "fiducials" define
the image coordinate system and its origo which is the
principal point of the image. In order to reconstruct the image
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996
