CoastGIS'99: geomatics and coastal environment
Cet article explique d’abord le principe de la scannographie aéoroportée puis, s’appuyant sur deux projets entrepris par Geodan Geodesie bv,
une présentation est faite de son application à la gestion intégrée du
littoral.
Introduction
Laser scanning is a new technique, which enables Digital Elevation
Model and Digital Terrain Model generation. It has very specific characteristics iike the ability to generate DTMs m forest areas. Other
advantages, which have been seducing Dutch users are the quick data
acquisition and processing, the high point density and the relative low
cost of laser scan data. The need for elevation data in the Netherlands
in the field of Coastal Zone Management (CZM) has stimulated the development of this new technique. Laser scanning is now an operational
tool, widely useci in data acquisition for CZM in the Netherlands. For
four years now, the entire Dutch coast has been surveyed every year by
means of laser scanning. Since 1994, Geodan Geodesie has been involved
in data acquisition using the ALTM 1020 laser scanner for the management of the Dutch coastal zone.
Airborne laser scanning
Concept
The principle of laser altimetry is rather simple. The basic idea is that
knowing the X, Y, and Z co-ordinates of a laser placed in a plane, the
attitude of the plane and the distance travelled by the laser beam, it is
possible to determine the X, Y and Z co-ordinates of the points hit by
the laser beam. This idea has first been applied to measure terrain profiles. The laser altimetry technique has been improved by sweeping
the laser beam, with the help of a mirror, across the flight track. In this
way a swath of the surface is surveyed. To implement this basic idea
into an operational technique, several instruments and techniques are
required. A GPS receiver placed in the plane and a GPS receiver placed on
the ground permit to position the laser beam during the flight by
means of kynematic differential Global Positioning System (dGPS). An
Inertial Navigation System is used to determine the changes in attitude of the laser scanner due to plane movements. The laser scanner is
used to perform distance measurements and the mirror of the laser
scanner gives the orientation of the laser pulses (fig. 1 ). The laser pulses
are emitted with a high frequency providing up to several elevation
measurements per square metre depending on the laser scanner parameters and flight characteristics.
Laser scanner characteristics
The laser scanner used in the under-mentioned projects (ALTM 1020)
emits laser pulses with a wavelength of 1 047 nm at a maximum pulse
150
Cet article explique d’abord le principe de la scannographie aéoroportée puis, s’appuyant sur deux projets entrepris par Geodan Geodesie bv,
une présentation est faite de son application à la gestion intégrée du
littoral.
Introduction
Laser scanning is a new technique, which enables Digital Elevation
Model and Digital Terrain Model generation. It has very specific characteristics iike the ability to generate DTMs m forest areas. Other
advantages, which have been seducing Dutch users are the quick data
acquisition and processing, the high point density and the relative low
cost of laser scan data. The need for elevation data in the Netherlands
in the field of Coastal Zone Management (CZM) has stimulated the development of this new technique. Laser scanning is now an operational
tool, widely useci in data acquisition for CZM in the Netherlands. For
four years now, the entire Dutch coast has been surveyed every year by
means of laser scanning. Since 1994, Geodan Geodesie has been involved
in data acquisition using the ALTM 1020 laser scanner for the management of the Dutch coastal zone.
Airborne laser scanning
Concept
The principle of laser altimetry is rather simple. The basic idea is that
knowing the X, Y, and Z co-ordinates of a laser placed in a plane, the
attitude of the plane and the distance travelled by the laser beam, it is
possible to determine the X, Y and Z co-ordinates of the points hit by
the laser beam. This idea has first been applied to measure terrain profiles. The laser altimetry technique has been improved by sweeping
the laser beam, with the help of a mirror, across the flight track. In this
way a swath of the surface is surveyed. To implement this basic idea
into an operational technique, several instruments and techniques are
required. A GPS receiver placed in the plane and a GPS receiver placed on
the ground permit to position the laser beam during the flight by
means of kynematic differential Global Positioning System (dGPS). An
Inertial Navigation System is used to determine the changes in attitude of the laser scanner due to plane movements. The laser scanner is
used to perform distance measurements and the mirror of the laser
scanner gives the orientation of the laser pulses (fig. 1 ). The laser pulses
are emitted with a high frequency providing up to several elevation
measurements per square metre depending on the laser scanner parameters and flight characteristics.
Laser scanner characteristics
The laser scanner used in the under-mentioned projects (ALTM 1020)
emits laser pulses with a wavelength of 1 047 nm at a maximum pulse
150