Advanced Image Processing Tools
for Future Satellite Image
Exploitation Systems
Jacques-Ariel Sirta, David Canu Frederic Perlant,
Laurent Peytavin and Nicholas Ayache
Laboratoire de Traitement des Images et du Signal
Matra Systemes et Information
6, rue Dewoitine
F-78142 Velizy-Villacoublay-France
Tel : 33-1-34.63.76.09 Fax : 33-1-34.63.76.23
Email :asirat@mantra-ms2i.fr
Abstract
Image processing is a key technology for operational exploitation of satellite images. Beyond image quality considerations, a crucial issue consists in providing the final user with real-time value-adding tools. We have followed a progmatical approach in transferring the most promising image processing algorithms from fundamental research to operational systems. This is discussed on automatic change detection, automatic extraction of 3D models from high resolution images and on selective compression for dissemination through communication networks.
Introduction
During the last decade, remote sensing applications of satellite imagery have been investigated through an 'experimental' approach: a few imaging satellites have been launched and exploited by national space agencies in order to demonstrate the feasibility of remote sensing applications in the field of cartography, resource or disaster monitoring, etc. (see for example [1-4]. In the future decade, we should get into an 'operational' phase with a significant number of observation satellites-including commercial programs-covering a large spectrum of sources from optical (multi-spectral or high resolution) to SAR sensors. Moreover, access times shorten rapidly, due to higher revist frequency provided by multi-satellite ground stations and to dissemination through communication networks. This paves the way to operational, quasi-real-time exploration systems.
In these systems, image processing is a key-technology for :
- guaranteeing image quality,
- establishing and exploiting the complementarity between the various sources,
- providing (semi)-automatic tools for real-time applicative exploitation and dissemination towards the end-user.
This paper synthesizes the most recent and significant results on multi-source applications using advances image processing methods, obtained in the Image and Signal Processing Laboratory of MATRA Systems et Information.
From Fundamental Research to Operational Systems
Our approach to bridge the gap between academic research and operational systems is based on simple and pragmatical principles:
- identifying in the Research Community the most relevant image processing emerging methods,
- evaluating those methods in comparison with state-of -the-art approaches using satellite images or simulations and ground truth data,
- taking into account constraints at system level (revisit time, application specific issues, available data etc.),
- evaluation mock-ups of operational tools based on the selected methods through 'proof of concept' demonstrations by application specialists.
We have thoroughly investigated the application relevance of various SAR and optical sources/chanels in order to get beyond basic statements (eg. Cloud coverage when comparing SAR and optical data). Three issues have been selected for this paper:
- multi band/ multipolarized SAR data,
- SAR interferometry,
- hyperspectral data.
Quantitative evaluation of SAR interferometry for various applications
MATRA Systems & Information has led a European consortium of 9 scientific partners in a project for the European Space Agency (ESA/ESRIN). The INSAR project aimed to evaluate and quantify the relevance of RS-1/2 Interferometry data for the following applications:
-
production of Digital Elevation Models for cartography [5],
- Hydrology using detailed terrain models,
- Forestry (estimation of forest parameters and changes),
- Glaciology (measurement of small motions using differential interferometry),
- Earth Science (studying earthquakes and volcanoes).
Several test sites on various Earth areas have been use to compare results with other remote sensing data (SPOT etc.) and ground truth data (GPS etc.).
