National Report of Switzerland
New Developments in Swiss National Geodetic Surveying
E. BROCKMANN, M. KISTLER, U. MARTI, A. SCHLATTER, B. VOGEL, A. WIGET, U. WILD 1
1
long GNSS baselines and some practical tests using
GNSS data in real-time, the necessary GNSS equipment was purchased at the end of 2006. Besides these
activities, the operation of the AGNES network for its
different applications such as monitoring of the national reference frame, estimation of zenith total delays for
numerical weather prediction, and the real-time positioning service swipos®, was very stable.
Introduction
A big milestone in Swiss federal surveying was
reached at the beginning of May, 2007. A transformation tool for converting coordinates of the old Swiss
reference frame LV03 to the new undistorted reference
frame LV95 could be made available to users. Developing the triangle definition file CHENyx06, containing 12,000 triangles whose angle points are defined
with coordinates in both systems, was a major challenge in the last years for the surveying authorities of
the 26 Swiss cantons and for the Swiss Federal Office
of Topography swisstopo. With the coordinate transformation tool FINELTRA, which is based on a finite
element approach, the transformation can be realized
with an accuracy of about 2 cm.
2
Fundamental Station Zimmerwald
In October 2006, the Zimmerwald Observatory celebrated its 50th anniversary. The observatory was founded in 1956 by the Astronomical Institute of the University of Bern primarily for the observation of stars. Between 1957 and 1991, a total of 49 supernovae, 7
comets and more than 100 minor planets have been discovered. The old observatory in Bern, which was built
in 1812 and was the predecessor of Zimmerwald, was
central in establishing the reference system CH1903 for
surveying as well as for the National Topographic
Maps of Switzerland.
During 2007, the Automated GNSS Network of Switzerland (AGNES), presently consisting of 31 permanent GPS stations, will be equipped with GLONASScapable receivers and antennas. The preparation work
for this enhancement with GNSS (Global Navigation
Satellite System) started at the beginning of 2006.
After some basic tests with respect to data analyses of
Zimmerwald
Observatory
Astronomical Institute
University Berne
Cooperating Institutions and Instruments
1956 – 2006
1
„Old Telescope“ (0.4/0.6 m Schmidt- und 0.6 m Cassegrain-Instrument)
2
ZIMLAT (1 m Laser- and Astrometry-Telescope)
3
ZIMSMART (0.2 m SMall Aperture Robotic Telescope)
swisstopo
Swiss Federal Office of Topography
Wabern
4
8
GPS antenna: IGS/AGNES reference station
5
GPS/GLONASS antenna(s): IGS stations
6
Temporary GPS/GLONASS receiver
2
5
1
3
4
2
6
9
7
7
ZIMLAT (Laser- and Astrometry-Telescope)
Geodesy and Geodynamics Lab GGL
Institute of Geodesy and Photogrammetry
ETH Zurich
Earth tide gravimeter
Section Microwave Physics
Institute of Applied Physics
University Berne
6
8
Remote sensing of the atmosphere
Competence Centre Air pollution Control
Ministry of Economic Affairs of the
Canton Berne
9
Ozone measurement station
Fig. 1: Poster shown at the 50th anniversary day of geostation Zimmerwald. The different observation techniques are
indicated by bullets. New is the left-hand part of the building hosting the atmosphere observations of the
Institute of Applied Physics (IAP).
Today the reference point of the new federal survey is
located in Zimmerwald. Due to the various collected
1
Swiss Federal Office of Topography swisstopo, Geodesy Division, Seftigenstrasse 264, CH-3084 Wabern, Switzerland,
Phone: ++41 31 963 21 11, Fax: ++41 31 963 24 59, e-mail: elmar.brockmann@swisstopo.ch, Web-Site: http://www.swisstopo.ch
observations (see Fig. 1), the Zimmerwald Observatory
should really be considered as an astro-geodetic observatory, in short a geostation.
tem LN03 and heights of the new orthometric height
system LHN95, was further developed and made available to users (see also Chapter 6).
For international surveying and for the connection of
the Swiss reference frames to the international frames,
Satellite Laser Ranging (SLR) observations and observations of the Global Navigation Satellite Systems
(GNSS) and their integration in global networks are
essential.
For the modernization of the national gravity network,
a new absolute station was established and observed in
Basel, replacing the destroyed station Pratteln. A relative gravity campaign was carried out in July 2006 in
collaboration with the University of Lausanne to connect the absolute stations and to re-determine some 1st
and 2nd order gravity points (Basel, Lausanne, Berne,
Zurich and Freiburg).
SLR/CCD
Zimmerwald continued to deliver observations to the
ILRS community with an excellent performance. The
quality of the observations was improved by a new
calibration method and new counters used for the time
measurements. The main developments in 2006 focused on preparing the replacement of the laser system and
on setting up a new station computer (transition from
VAX to Linux operating system). In April 2007, the
laser system was evaluated and the new station computer was used operationally. For several years the
telescope has also been used for optical measurements
using a CCD. The switch from SLR to CCD and viceversa was further optimized, resulting in an increase in
the number of observations for both techniques.
GNSS
The Trimble GPS receiver ZIMM and the Javad GNSS
receiver ZIMJ continuously delivered data to the IGS,
EPN and AGNES networks. As preparation work for
enhancing AGNES from GPS to GNNS, a Trimble
NetR5 receiver was installed in July 2006 (Fig. 2). Its
data were analyzed by swisstopo and by the CODE
analysis centers.
Additional observations
A new building (left-hand part in Fig. 1) was finished
in October 2006. The Institute of Applied Physics of
the University of Berne already installed several
instruments for atmosphere observations (e.g. the All
Sky Multi Wavelength Water Vapor Radiometer
ASMUWARA) on the roof of this extension building.
4
Permanent GNSS Network AGNES
and Positioning Service swipos®
A new station Hasliberg, situated at almost the same
altitude as the users of the swipos® positioning service
in this region, was added to the AGNES network in
mid-2006. This station is a replacement in the VRS
processing for the AGNES station Jungfraujoch which
is located at 3500 meters above sea level. The data of
the Jungfraujoch station will mainly be used for
scientific purposes such as GPS meteorology.
The maintenance and operation of the permanent
GNSS network AGNES proceeded smoothly and without any major problems. The mean availability of the
swipos® positioning service in the year 2006 was about
99%.
The number of customers with an annual licence could
be increased due to price reductions announced at the
end of 2005.
During 2007, the AGNES network will be equipped
with GLONASS-capable receivers and antennas. The
preparation work for this enhancement with GNSS
started in 2006. After some basic tests with respect to
data analyses of long GNSS baselines using a temporarily installed NetR5 receiver in Zimmerwald (Fig.
2), and some practical tests using GNSS data in realtime, the necessary GNSS equipment was purchased at
the end of 2006.
The earth tide gravimeter ET25 was temporarily deinstalled during the construction work of the new
building. After an interruption of almost 8 months, observations have now again been available since November 2006. The impact of the new building, which is
located directly above the gravimeter cellar, on gravity
measurements was determined by comparing the time
series of semi-annual absolute gravity measurements
which are carried out by the Swiss Federal Office for
Metrology (METAS) using a FK5 instrument. The
reduction of about 10 gal of the last measurement in
October 2006 needs to be validated by the next measurements.
3
Gravity Field and Geoid
The activities in 2006 were focused on the establishment and the support of the geoid model CHGeo2004,
which is already widely used in Switzerland after its
publication in March, 2005.
The transformation software HTRANS, which allows the
transformation between heights of the old height sysPage 2
Fig. 2: GNSS antenna of the Trimble NetR5 GNSS
receiver temporarily installed in Zimmerwald
for test purposes
The purchased GNSS antennas were individually
calibrated using a robot from the firm Geo++ (absolute
calibration) [Wübbena et al., 2006].
The main reason for upgrading the AGNES network by
GLONASS-capable receivers is data availability for
real-time users. Due to unavoidable coordinate jumps
in the coordinate time series, 10 of the 31 AGNES sites
will continue to observe only GPS data with the actual
equipment. On these 10 stations, the new GNSS receivers will be set up on a near-by antenna mount before
the end of 2007. The replacement of the equipment on
the other 21 sites will begin at the end of June 2007
(see [Ineichen et al., this volume] for further information).
The commercial positioning service swiss@t (Swissat
AG), which used GPS-GLONASS-combined Javad receivers on reference stations right from the beginning
and which has competed with the swipos® positioning
service for several years, plans to stop operations at the
end of 2007 at the latest. Since the beginning of 2006,
swipos® support had already taken over the responsibility for swiss@t customers and for operating the two
simultaneously running reference networks. It is planned to migrate the users of the swiss@t service to the
swipos® positioning service and to deactivate the
swiss@t reference network by the beginning of 2008.
5
stations, the capability of processing GLONASS observations (GLONASS ambiguity float) as one out of two
EPN analysis centers, and the estimation of troposphere gradients were performed in close international
cooperation. These changes partly affect the coordinate
estimates quite significantly. For consistency with the
previously generated time series, swisstopo also continued to process some solutions based on the "old"
models.
Some statistical performance numbers characterize the
stable operation of the AGNES network and its analysis: in 2006, 99.51% of the AGNES sites were used in
the daily analysis, and hourly monitoring was available
for coordinates and for troposphere parameter submissions to E-GVAP for 98.78% of the time.
With respect to the planned enhancement of the
AGNES network with GLONASS, see Chapter 4.
Permanent Network Analysis Center
The hourly solutions which are done for monitoring
purposes and for contributing to numerical weather
prediction in the framework of the EUMETNET EGVAP project (Network of Meteorological Services;
Project GPS Water Vapour Programme) were refined
by the following improvements [Ineichen et al., 2006
and Brockmann et al., 2006]:
 Extending the network by additional stations (120º
x 45º instead 30º x 15º).
 Optimizing the weighting scheme of the troposphere parameters in order to reduce the effect of
weakly estimated parameters due to the satellite
geometry.
 Quality checks by comparing the near real-time
results with post-processed results.
The development of a monitoring system which displays the processing status on the web graphically was
a major milestone. As shown in Fig. 3, the status of the
available RINEX files, the status of the distribution of
hourly troposphere results and the status of the stability
of the coordinates is displayed using a simple colour
scheme. The web page also allows the study of the
coordinate time series of the last several hours, days,
months and years [Brockmann, 2006].
In November 2006, several model changes were realized in the different daily and hourly analysis products
(e.g. swisstopo's contribution to the EPN) starting with
GPS Week 1400. The change of the reference frame
from ITRF2000 to ITRF2005/IGS2005, the use of the
absolute antenna model igs05 and additionally available individual calibration values for some EPN
Fig. 3: Status of the RINEX availability of the used
sites displayed at www.swisstopo.ch
6
National Reference Frames
The end of 2006 marked the completion of a basic geographical dataset of greatest importance for establishing the spatial data infrastructure SDI for Switzerland:
the national triangular transformation network
CHENyx06 (Fig. 4). This new dataset permits the
elimination on the one hand of systematic deformations
resulting from the first national survey of Switzerland
completed in 1903 (LV03) reaching a maximum of 2 to
3 m, and on the other hand of local distortions from the
cadastral survey on the cantonal level.
Switzerland was subdivided into almost 12,000 triangles (6000 points), each having its own affine transformation parameters matched to local conditions.
Page 3
Difference LV95-LV03
Fig. 4: National triangular transformation network CHENyx06
In order to prove the accuracy of the transformation,
the cantonal authorities have measured almost 47,000
control points in addition. The results were excellent:
geographical data in Switzerland can now be transformed into the new LV95 reference frame or in a
European one such as ETRF with an accuracy of 2 cm
(± 1.1 cm) on average.
The national triangular transformation is also implemented in the Swiss GNSS Positioning Service
swipos® as a new real-time option. GPS users who
have to work in the old datum LV03 which is still valid
for many applications, can determine positions in this
frame with an accuracy of a few centimetres without
having to establish a local fit.
Furthermore, the new software REFRAME was developed to include all relevant transformations needed in
Switzerland (see Fig. 5). The software is available as a
client version as well as a web service.
The following transformations are supported:
 transformation LV03 ↔ LV95 in either direction as
defined by using the finite element transformation
FINELTRA
 geoid undulations with respect to the reference
ellipsoid (geoid heights CHGeo04)
 differences between the "official heights" of the
LN02 datum and the orthometric heights of the
LHN95 datum according to the HTRANS method
[Schlatter, 2007]
 transformation between Swiss national coordinates
and ETRS89
Page 4
Fig. 5: The user interface of the new "REFRAME"
transformation software
On May 3, 2007, swisstopo opened a designated
Internet platform for datum transformations
(www.swisstopo.ch/lv95). This platform provides
detailed information about the transformation process
and access to the official national transformation dataset. In addition, a free service allows the transformation
of geographical data into common formats such as
DXF, SHP or the national GIS standard INTERLIS 1, or
even formatted as text (separated by tabs or hyphens)
from the old LV03 frame to the new LV95 reference
frame and vice-versa as well as into the European
ETRS89 reference system (see Fig.6).
Last but not least, the accuracy of the transformation
for all of Switzerland can be accessed through a web
GIS application (Fig. 7) and the transformed data sets
can be exported in the KML format in order to visualise
the results in Google Earth or Google Maps.
for all other geobasis data by the end of 2020 (e.g. for
GIS applications).
00
…
06
work Δ-generation
07
08
…
16
change of the
reference frame
17
…
XX
renewal
data
LV03
LV95
reference
frame
LV03
LV95
Fig. 8: Time schedule for the introduction of the new
LV95 reference frame for geobasis data
regulated by federal law
Maintenance work in LV95 and LHN95
A small number of revisions was necessary for the 1st
and 2nd order points. A reduction in the number of
reference points in the old LV03 network was continued, and several 3rd order points were handed over to
the responsible cantons.
Six levelling campaigns were measured in 2006 – a
total of 220 km – and 170 km lines were revised for
measurement in 2007.
7
Fig. 6: The user interface of the Internet
transformation service
Fig. 7: Expected empirical accuracy of the
transformation in the region around Lucerne
Legal aspects of reference frames LV03 and LV95
Presently the Geographic Information Law is in the
consultation process in Parliament, together with 10
different by-laws and technical ordinances concerning
e.g. geoinformation, federal and cadastral surveying. It
is scheduled to come into force on January 1st, 2008.
In the drafts of the ordinances, it is foreseen that the
old (LV03) and the new (LV95) reference frames can
be used for the geobasis data regulated by federal law
by the end of 2016 (e.g. for cadastral surveying), and
Geodetic Projects
Control Point Data Service (CPDS)
The project CPDS has been running for several years
and will make information about all geodetic control
points available over the Internet. The central database
and a graphical user interface (version 1.1) for revisions and for the administration of the database by
the cantonal surveying authorities could be realized by
the end of 2006. The central database already contains
the data of 23 out of 26 cantons. It is expected that the
database will eventually handle about 24,000 points for
category LFP2 (0.5 points per km2, responsibility of the
cantonal authorities) and about 700 points for category
LFP1 (responsibility of swisstopo). The import of the
height control points is currently under development.
The public CPDS web site has been operational since
January 2006 and allows the display of the control
point information on background maps at different
scales. In addition, with different search functions (e.g.
by point number, coordinates, city names, etc.), information to the corresponding control points may be
accessed.
Other projects
The project GRIPS (Geodetic Reference data as
Internet Products and Services) and the project "GIS
extension for the national border" both deal with an
improvement of the Internet services. A follow-up
project of Swiss4D, which focused on the determination of a kinematic 3D model for Switzerland, is
currently being planned. These above-mentioned projects were described in [Wiget et al., 2006].
Page 5
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