ORFEO
plementing it
ich will serve
ional levels.
r comparison,
ents.
by COSMO-
R, developed
of resolution
ound Control
cts for easier
cquisition of
r to develop
Il décrit les
util adapté à
ire la plupart
n, aussi bien
radar seront
lution seront
seulement en
ique : même
ifiées seront
éographique
'réoscopique
teurs finaux
ptique.
| resolution
Quick Bird
t policy.
ty of small
Observation
) has been
n (about 80
h 3S2) with
vious SPOT
ind cheaper
nono-sensor
lite;
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B1. Istanbul 2004
Developing dual systems which could be used by
Defenses as well by Civilian bodies;
Finding new and important European partners;
Developing the use of Earth Observation by scientists
and institutional bodies.
This paper presents how Pléiades HR has been decided,
describes its characteristics and performances and indicates
which actions are undertaken for preparing the users to the
best use of Pléiades data combined with other space, airborne
and ground sources of information.
Chapter 2 presents the mission analysis from which
several systems have been proposed,
Chapter 3 explains how Pléiades HR has been chosen
among the previous candidates
Chapter 4 details the Pléiades HR system and its
performances.
- Chapter 5 presents, as a conclusion the ORFEO
Preparatory Program and international initiatives which
should help users to better benefit from Earth
Observation.
2 MISSION ANALYSIS
2.1 User's needs assessment
In order to identify which space systems should be developed
users were consulted, within a dedicated expert group and
through several meetings with the different user
communities. Results from other European studies, such as
ERSIS, made by major European industries for ESA, were
also taken into account. ;
For each of the main application domains information needs
had been evaluated and possible sensors to get these
information identified.
SAR and optical sensors are both required for most of the
applications, the first one mainly for its all weather capacity,
the second one for its better visual interpretation. It is also
acknowledged that external data from ground or airborne
surveys are in most cases needed to get reliable and accurate
information from space imagery.
2.1.1: Cartography: For basic mapping, land use planning,
urban surveys or telecommunication the use of space imagery
is already mature and well known (Konecny, 1999), even if
the complementarities and competition with aerial
photographs are still evolving quickly.
Three types of data are requested: high-resolution (metric or
sub metric) optical imagery, wide field imagery for medium
scale mapping of large areas and radar acquisition when all
weather capabilities are needed.
2.1.2 Agriculture: Precision farming, agricultural control
and crop statistics are application with great potentialities for
Earth observation if efficient methodologies could be used to
extract useful and accurate end users’ information. From
current experiments this appears to be feasible but has still to
be confirmed and operationally implemented.
Several types of data are needed but the key parameters are
the number (6 to 20) and choice of spectral bands with a very
good revisit time (to provide weekly information).
2.1.3 Forest: Space imagery (SPOT, ERS, Landsat, ..) is
already used for forest inventories but new application areas
could be envisaged for timber management or ecological
surveys. Many Earth Observation data are needed, from very
high optical photograph (relevant to airborne sensors) to
multi/superspectral data, radar imagery (P or L band) and
thermal data (especially for forest fires)
2.4 Hydrology: Water is considered to be one of the most
important issues for the future. Its management, either to
provide fresh water or to avoid catastrophic floods could be
facilitated using Earth Observation data, such as metric
optical or radar imagery and especially accurate Digital
Elevation Models derived from stereoscopic or
interferometric data. Most of the potential users (insurance
companies, water providers, civil protection, ..) are not yet
familiar with such remote sensing data and they should be
involved as soon as possible in the development of the
applications.
2.1.5 Geological prospects: Geology was one of the first
application domains of Earth Observation and remains an
important one, with a very diverse need of data, at several
resolutions, with as many spectral bands as possible, and with
always stereoscopic and/or interferometric demands.
It is noted that for mining surveys there is a special interest
for hyper spectral data.
2.1.6 Dynamic geology and associated risks: As for
hydrology the potential interest of Earth Observation for
dynamic geology and associated risks (earthquakes,
volcanoes, landslides, ..) is far to be fully exploited and
GMES initiative could help to develop the use of space data,
coupled with continuous ground surveys, for such
applications. The needs for high resolution, either optical or
radar (X band), and for fast services (within few hours or
days) have been identified as well as complementary sensors
(wide field, thermal, SuperSpectral and C or L. SAR).
2.1.7 Marine applications: Even if Pléiades has not been
designed to fulfill marine applications, some of these
applications could be envisaged, either for oceans, sea ice or
littoral surveys, especially with wide field imagery and C
band data.
2.2 Sensor assessment
As a result of these mission analysis 10 sensors (or
acquisition techniques) have been identified to fulfil most of
the users’ needs. The required parameters are described in
Table I.
Component Resolut Swath Band | Revisit
ion (m) | width (km) number time
T (days)
WF: Wide Field 2-5 40-100 3-4 3-7
HR: Optical HR =] 10-30 3-4 1-2
SS: SuperSpectral | 3-10 100-300 6-20 1-2
HS: Hyperspectral | 5-20 50-300 30-200 2-7
TH: Thermal 1-40 100 TBD «]
C:SAR C 2-4 50-300 1-2 1-5
X: SAR X 1-5 10-300 1-4 «]
L: SAR L 2-10 50-100 1-4 1-7
P: SARP 5-10 70-100 1-4 1-7
IF: Interferometry 1-5 70-100 NA NA
* For SAR the number of bands is the number of polarisation
channels
Table 1: Sensors requirements