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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
Based on the standards for laser altimetry currently used in The
Netherlands and Flanders, a similar set of requirements is
obtained for the aerial laserscanner (Table 3).At a nominal
flying altitude of 14 km, with a ceiling of 18 km albeit with
perhaps restricted capabilities, a scanangle of 6? is foreseen so
that the swath widths of multispectral camera and the
laserscanner coincide. The complete payload description and
the UAV issues are described elsewhere (Everaerts et al., 2004).
Pulse frequency [5 kHz
Laser beam divergence «0.1 mrad
Scan frequency At least 10 Hz
Scan mode Nutating
[ntensity Yes
Multiple reflections Yes
Data volume 26 Mbit/s
Estimated weight «5 kg
Continuous use on daily basis | at least 8 h during equinox
Table 3. Basic requirements for the laser altimeter
3.3 Ground segment
Based on previous experience at Vito with the Processing and
Archiving Facility for several satellite sensors, a centralized
ground processing center linked to multiple ground rececption
stations will be installed (one reception station supports the
HALE UAV in a radius of 200 km). One of the key features of
the PEGASUS system is the centralized data processing from
level 0 (raw data) to level 2 and level 3 data under standardized
quality control procedures. This centralized and qualified
ground segment guarantees users across Europe the same high-
quality data as presently delivered by satellite data providers.
This is not the case in the aerial survey business world where
only the instruments are standardized, as there are just a few
large manufacturers left (e.g. Leica Geosystems and Z/I
Imaging for aerial cameras).
The multispectral data will not have stereo capability, due to the
narrow view angle. The stereo aspect will be generated from the
overlay of the multispectral data with the aerial laserscan data
as elevation measurements derived from aerial laserscan data
have a higher accuracy and consistency than those derived
through photogrammetry at the same flying height. Therefore
stereo multispectral data will be available but as a level 3 data,
i.e. after merging the laserscan data with the multispectral data.
4. BUSINESS MODEL
The main features characterizing the business model of the
PEGASUS project can be summarized as follow:
The PEGASUS project, by its targeted ground resolution, offers
an alternative for aerial photography and aerial laserscanning
data from a photo scale of 1:8 000 and smaller. These data will
be comparable to and compatible with present-day modern
digital airborne systems like Leica ADS 40, Leica ALS 40.
ele...
Because several complete overpasses and observations per year
will be performed and be made available to end-users across
Europe, all required data will usually be available immediately.
Even for disaster monitoring, nearly real-time data from the
hovering UA V’s will be available to the decision makers.
627
There will be one centralized and quality-assured system for the
whole of Europe. This system will respond to the highest
quality standards set for large scale digital mapping (the GRB-
standard in Flanders and the elevation mapping standards in the
Netherlands and Flanders). This will ensure mapping agencies
and end-users of the desired quality without needing to wait for
the appropriate flight season or the availability of sensors, or
buying expensive equipment themselves. This centralized and
quality-assured system will rely mostly on fully automated
procedures for the production of data up to level 2, with
substantial manual or semi-automated data quality checks and
re-runs. The future is clearly for a centralized (state-wise or
European wide) data and information provider with certified
quality-approved production systems, standardized across
Europe. All the data and subsequently derived information
products will be available to both end-users and OEMs. This
allows for a large dissemination and use of RS data in the
society as a whole and not just among the current specialist
users. OEMs will be able to define their own level 3 data.
The data will be delivered at a cost significantly lower than
presently by wholly owned data acquisition. This is due to a
better time-use and hence lower operating cost than present-day
systems. Indeed, a specific UAV is targeted for a survey area
varying between 100 000 km2 and 150 000 km2 at an system
acquisition cost, inclusive of payload, of approximately 10 M€.
This amount is significantly lower than the acquisition costs for
the multitude of aircrafi, digital and analog cameras and
laserscanners presently needed to cover the same area..
Furthermore, both digital and analog cameras are only used
under *blue sky" conditions (1/8 of cloud cover and preferably
less). No data acquisition is undertaken when cloudy patterns
are observed or forecast as the cost for mobilizing crew,
aircraft, operating cost of the aircraft, etc., are too high
compared to the potential profit of data collection. In contrast
the UAV will hover continuously over the area and collect data
as soon as any area of 2 x 2 km” (on the ground) can be
recorded cloud-free. This leads to vastly expanded operating
hours as compared to today's airborne systems.
Moreover, the use of fully automated and/or semi-automated
data QA/QC lowers the production cost of the data and
information even further. More integrated automated solutions
can be used because of :
l. the integrated design of the different sensors by the
same manufacturer,
the completely digital set-up of all sensors and data-
acquisition, and
3. the large development effort on the part of payload
manufacturer i.c. Vito, as a research organization, to
also spend considerable time improving the data
processing algorithms.
Io
Traditional hardware manufacturers only provide the hardware,
but seldomly the automated tools to ensure quality-approved
information collection.
Vito, as founding and chief scientific partner in the PEGASUS-
project, has growing evidence of this theory in its own running
data-information dissemination policy with regard to
VEGETATION satellite data.
Figure 4 shows the dramatic increase of subscribed users to the
centralized VEGETATION satellite-data and -products once the
