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ler", "IRAS B", "GeoVec","ModelView") are used for
training in digital photogrammetry, raster mapping, height
modelling and GIS. Three workstations of Silicon Gra-
phics, type INDY, were recently procured together with
a software package for the automatic generation of height
models ("Match-T"). A PC based image processing sy-
stem is also available. Various triangulation packages
such as "MR2", "Bingo", "BLUH" are used in project
work. Some terrestrial cameras are available: one UMK
(Carl Zeiss Jena), one Rollei 6006 with réseau, a Has-
selblad camera and a low cost digital camera. Scanning of
images can be carried out by a document scanner (HP's
"Scan Jet") with limited geometric quality.
Besides the photogrammetric and image processing equip-
ment the laboratory posseses a number of graphical and
GIS workstations which are equipped with software
packages such as AutoCAD, Microstation, Mapinfo and
GeoCAD.
The laboratory has quite a number of surveying equip-
ment, such as levels, theodolites, total stations, GPS
receivers including PC based processing stations which
are used by the students for control point determination.
Research
"GeoCAD" software system. The mapping and GIS
package "GeoCAD" which is jointly developed and
marketed of AAU and two surveying companies has now
received some photogrammetric features. Besides ob-
ject-oriented data collection from an analytical plotter,
software routines were added for plotting from single
photographs and for height models. The complete pack-
age is running under the operating systems UNIX, Next-
Step and Windows NT.
Automatic orientation of images by means of existing
maps. Updating of digital maps requires orientation af
new aerial images. This process can be automated by
using special objects from an existing topographic data
base. An optimal fitting of new information into the
existing data base should use a large amount of objects.
A Ph.D. work is investigating what type of objects and
procedures will have to be used in the matching between
map and pictorial information. First results show that
point type objects such as man hole covers and gratings
can be measured nearly automatically by means of a
templet which is derived from an adjustable graphical
mark. Road intersections can also be converted into
templets and matched with sections of the image which
contain the same road intersection. Various types of
correlation techniques as well as image pyramids are
applied. The investigations are of importance to various
mapping techniques including the production of ortho-
images.
Semi-automatic generation of digital elevation models
incl. editing and visualization. In an other Ph.D. project
the accuracy, completeness and speed in the generation
of elevation models by means of matching techniques are
investigated. Areas with dense vegetation, poor texture, as
well as. built-up areas are problematic for an accurate
height determination by image matching techniques.
Efficient checking and editing facilities are important for
a succesful application. Appropriate analyzing and visua-
lization methods have been used and will be further
developed. The parameters which have influence on the
results are studied by means of various test models co-
vering different types of the Danish landscape. The inve-
stigations have importance for the derivation of a nation-
wide height model and orthoimage coverage.
Computer-assisted learning for digital photogrammetry.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996
New tools from the computer technology influence the
production of CAL software for photogrammetry. Inve-
stigations of advanced PC models, new storage media like
CD-ROM and Photo-CD as well as object-oriented pro-
gramming techniques and authoring software were carried
out. Several CAL programs from other fields were stu-
died. Some of the new tools and techniques were applied
in the development of a new CAL program "Learning
about digital photogrammetry" ("LDIP"). Finished themes
and exercises deal with image correlation and their ap-
plication. Parts of the program were already used in the
education of chartered surveyors at Aalborg University.
Photogrammetry for 3D visualization. Photorealistic
models of planned constructions and their surroundings
render possible a better communication.In order to derive
a 3D wire model of houses and to add pictorial infor-
mation to the facades, amateur photography, scanned and
stored on a Photo-CD, was used. By means of existing
map data the exterior orientation of the camera was com-
puted and dimensions inside and outside of the facades
were then derived from single images in order to com-
plete a 3D-wire model of the town houses. The images
were resampled and cut so that they could be placed to
the facades of the houses. All of the computations were
carried out on PCs. ‘Other project work in this field dealt
with the visualization of windmills and their surrounding
landscape. New perspective images of the landscape were
generated from a coloured orthoimage and then combined
with the 3D-model of the planned windmills. Professional
workstations were used in this work.
With regard to remote sensing various program packages
like "Imager" (Intergraph), "Imagine"(Erdas"), "Chips"
(University of Copenhagen) and others were tested and
used in project work of the students.
Experiences from earlier research about digital ortho-
images and photogrammetric surveying of underwater
areas were used by the Danish mapping industry in va-
rious and extensive projects.
J oachim Hohle
DANISH CENTER FOR REMOTE SENSING
The Danish Center for Remote Sensing (DCRS) is one of
the centres of the Danish National Research Foundation.
It is located at the Department of Electromagnetic Sy-
stems (EMI) at the Technical University of Denmark. The
centre conducts research relating to instruments for remo-
te sensing and their application to Earth Observation and
Earth Science. DCRS primarily uses data from synthetic
aperture radar (SAR) systems, which are high resolution
imaging, airborne or space borne radars. EMI has deve-
loped a dual-frequency, fully polarimetric and inter-
ferometric system, EMISAR, which is operated on a
Danish Air Force Gulfstream G-3 aircraft.
DCRS has in collaboration with Aalborg University
conducted a pilot project examining the potential of using
polarimetric SAR data for updating of maps. Another
project with the same objective has just been launched in
collaboration with the National Survey and Cadastre.
The principal DCRS activity in the field of photogram-
metry and remote sensing is, however, related to the
generation of digital elevation models (DEMs) using SAR
interferometry - both single pass and repeat pass.
EMISAR single pass SAR interferometer. The EM-
ISAR system has been augmented with a single pass
