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satellite images in Switzerland is limited to research 
projects. This could change if images of higher resolution 
were available. However one has to consider that in 
Switzerland very good aerial images are available since 
many years at relatively reasonable prices. 
1.2.5 Digital Cartography 
At the ISPRS Congress in Kyoto 1988 a paper was 
presented (Eidenbenz/Perret, Commission IV) concerning 
map revision by means of digital cartography. It describes a 
hybrid raster-vector method. In the meantime the positive 
results of this test have been proven by applying it to two 
more map sheets. Unfortunately the provider of the system 
which was used decided to reconsider his market 
orientation which made it necessary for us to re-evaluate 
the project. Now we stand shortly before the end of this 
phase which promises to be successful. However we 
estimate that the acquisition and implementation phase will 
last various years (map revision cycle), in which the 
conventional analogue and the new digital techniques will 
have to continue side by side. Therefore we do not foresee 
any immediate savings. We are also concerned by the 
breathtaking speed of developments and the short life 
cycles mainly of the hardware but also the software. It 
seems as though we will have to adapt ourselves to not only 
replacing our maps in one revision cycle but also the hard- 
and software systems. 
1.3 Federal Directorate of Cadastral Survey 
Already in 1978 a rough concept for a reform of the official 
cadastral survey was launched. Among other objectives it 
was postulated in the guiding principles that the official 
cadastral survey was to orient itself towards a spatial 
information system and that this reform should also lead to 
improved services to the industry, the utility companies, the 
government and to the citizen through an increased 
adaptation to the needs of these users and their economic 
possibilities. 
When the decree for this new official cadastral survey and 
its technical ordinance was put into force the basis was 
created for the official cadastral survey to fulfil its original 
objective of securing all property rights and on the other 
hand the foundation was laid for the creation and operation . 
of Land Information Systems (LIS). 
An essential tool was created for this purpose: a uniform 
data model containing a structured basic data set with its 
own uniform descriptive language AVS/INTERLIS. Great 
importance was placed on the parameters which define 
data quality. Therefore the following values have been 
described explicitly in this data model: accuracy, reliability, 
timeliness, completeness and consistency. 
Financing is carried mainly by the public entities such as the 
state, the cantons and the municipality. But new financial 
models are being studied to increase participation of LIS 
users. 
Thanks to the comprehensively described data model it was 
possible to avoid detailed regulation of individual processes 
such as data collection, data processing and data 
management. In line with modern quality assurance the 
77 
contractor is free to choose from an ever increasing array of 
innovative methods to fulfil his contractual obligations. On 
the other hand the contractor himself is responsible for 
quality assurance. Already in larger contracts which have 
been tendered on a submission basis it is discernible that 
those win the contract who have implemented efficient 
economical methods maintaining the required quality 
standards. Specifically for the information layers describing 
surface coverage, single objects and the digital terrain 
model (initial survey and periodic revisions) 
photogrammetric methods will assert themselves without 
doubt. Depending on land value also the orthophoto will 
impose itself as an economical source of additional 
information. 
Increasingly GPS methods are being used in the official 
cadastral survey. These methods produce tension-free 
networks of ground control points in an efficient way. 
Simultaneously the Federal Office of Topography has 
established a basic geodetic reference network (LV95) with 
which the existing national survey has been thoroughly 
modernised. We are now evaluating the possibilities to 
adapt the whole official cadastral survey into this new 
reference frame in an optimal way and without loss of 
quality. 
The Federal Directorate also maintains an aircraft with dual 
LEICA RC30 cameras combined with the ASCOT GPS 
aerial survey navigation system. Main applications are large 
scale photography for cadastral purposes and periodic 
coverage of all forested areas with false colour photography 
to establish a forest health inventory. 
2. PHOTOGRAMMETRY 
Based on a recent study photogrammetry in Switzerland is 
undergoing a rapid transition from analytical to digital 
photogrammetry. In 1992 some 50 analytical instruments 
were in use and only 15 analogue instruments which had 
been digitised. To date 15 fully digital photogrammetric 
stations and 5 scanners are in operation whilst the number 
of analytical instruments has diminished. Practice is 
showing that digital systems are economical when DTMs 
and orthophotos are required. However it is also evident 
that large scale mapping gives better results if details can 
be interpreted through high-quality optics of an analytical 
instrument. 
2.1 Photogrammetric facilities 
The government is represented in this field by the following 
institutions: the Federal Office of Topography, two 
Technical Universities (Zurich and Lausanne), two 
Technical Colleges in Muttenz and Yverdon-les-Bains and 
a Federal Research Institute in Birmensdorf. The private 
sector is represented by 23 private companies with 1 to 4 
instruments each. 
In the field of aerial surveys the Federal Office of 
Topography and the Federal Directorate of Cadastral 
Surveys each are using an aircraft with dual cameras. Both 
government institutions are using GPS for flight navigation. 
7 private companies are using a total of 8 cameras. Mostly 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996