INSAR Quantitative Evaluation
| B. Carron
||Laboratoire de Traitement des Images et du Signal, MATRA CAP SYSTEMES, BP 14, 6 rue Dewoitine, 78142 VELIZY VILLACOUBLAY
will present the INSAR Quantitative Evaluation Study, conducted
for ESA/ESRIN. The INSAR consortium coordinated by Matra Cap Systèmes
gathers 9 European partners to validate interferometry for 5 applications
over more than 15 test sites, from Antarctica to northern Norway
Islands. The INSAR project aims to evaluate and quantify interferometric
SAR approach towards conventional measurements, with ground truth
reference data, in the field of the following applications : digital
elevation model (DEM) production ; hydrology ; forestry ; earth
science (earthquake and volcanoes monitoring) and glaciology (ice
Keywords:quantitative evaluation, applications,
interferometry, INSAR project
INSAR Consortium partners are 10 industrial and academic organizations
working on SAR images in different fields :
- CNES, Toulouse, France. (interferometry expert)
- Chalmers University of Technology, Göteborg, Sweden.
- GRGS, Toulouse, France. (earthquake monitoring)
- Institut für Navigation, Stuttgart, Germany. (glaciology
- Institut de Physique du Globe de Paris, Paris, France. (volcanoes
- ISTAR, Sophia Antipolis, France. (DEM production)
- Norsk Polarinstitutt, Oslo, Norway. (glaciology in arctic)
- Remote Sensing Laboratories, Zurich, Switzerland. (DEM production
- Synoptics, Wageningen, the Netherlands. (hydrology)
- MCS, Vélizy-Villacoublay, France. (DEM production)
Management of the INSAR project is performed by MCS. Technical
reporting is performed by ESA experts. We will focus our presentation
on the three scientific tasks in which MCS is involved: Project
organisation, DEM production, INSAR processor system specification,
and WWW demonstrator
INSAR project is conducting for ESA/ESRIN by MATRA CAP SYSTEMES,
leading to a quantitative evaluation of the INSAR technique towards
several applications and their conventional measurement techniques.
The project has begun in march 1995, and will end before the end
of the year. An European Consortium has been constituted, composed
of the industrials and academic organizations detailed on figure
1. All the members of the INSAR Consortium have an expertise
in their application area, and the applications are covering a
large spectrum :
DEM production : three techniques are evaluated : ISTAR, RSL (Small 1996)and
Hydrology : interferometric DEM are compared with SPOT DEM and
GPS measurements, and coherence is used in hydrological models
Forestry : interferometry can detect with forest changes, and
gives an estimation of the forest parameters (Chalmers University
of Technology Dammert 1996 & Askne 1996
and RSL) ;
Glaciology : at Norsk Polarinstitut (Lefauconnier 1996)and
Institut für Navigation (Rott 1996)
ice movements and quality are to be measured in arctic and antarctic;
Earth sciences : both earthquakes (Feigl 1996)and
volcanoes monitoring (Briole 1996) applications
Figure 1: Composition of the Consortium
Several test sites have been chosen by the members of the Consortium
all over the world. Following figure gives examples of the test
Figure 2: Some of the test sites
The INSAR project
The INSAR project includes the following parts :
Management of the Consortium
a common evaluation methodology
is needed from all the members of the Consortium ;
application evaluation (all members of the Consortium, see
INSAR processor system specification
ESA has delivered an important number of images in the INSAR study,
so that each member of the Consortium may process interferograms,
and evaluate its method towards its application extensively.
ESA is also the technical expert for all the application evaluation.
In order to get all the quantitative results available in a common
form, a generic evaluation method is to be used by all the members
of the INSAR Consortium. For example, for each application, the
following items are needed :
An overview of the application is performed
- what is the context of the application area
- what are the common sources of data for that application
- a connection with radar interferometry is to be added
- The conventional measurement techniques are described
- what are the problems or drawbacks of these methods
- what is new with interferometry
- Specific works include
- test sites description
- problems addressed in the evaluation
- detailed results over each test site
- Some of the members of the INSAR Consortium will present their
results at FRINGE 96, and the hole package will be available
at ESA at the end of the project.
H. Tarayre has developed during her PhD-thesis at MCS (Tarayre, 1996 a)
a software to produce DEM with interferometry. Production of Digital
Elevation Models (DEM) from SAR images through INSAR, seems now
possible by using semi automatic phase unwrapping algorithms.
This approach will provide a third method to evaluate the DEM
production techniques with interferometry (ISTAR, RSL and MCS).
The following example has been used for the algorithmic validation,
in France, over Vosges. First image is the DEM produced and second
one a combination of the orthorectified amplitude and coherence
(click on the images)
A validation based on ground control points coming from 1/25000
scale maps (Tarayre 1996 b) give a rms
error of 15 meter for a hilly terrain, and 35 meters on stronger
relief area, to be compared to the theoritical error from 10 to
Another test site has been choosen over Marseille, with TANDEM images.
MCS will unwrap the fringes, and produce the DEM, and the
final validation is to be performed by ISTAR, using the ISTAR
DEM Marseille database as a reference.
Based on CNES expertise (Massonnet 1996)
an INSAR processor system has been specified by MCS, designed
to be able to produce high level interferograms. Main steps of
the INSAR processor system are :
- correlation of the two input images, and interferogram computation ;
- DEM ingestion and simulation over the input DEM (suppression
of the fringes from the known terrain), then filtering of the
- optimisation of the phase function.
- An interferometric quicklook facility is foreseen in a massive
interferometric production system, at least in order to choose
quickly correct interferometric couples (based on coherence criteria).
At the end of the whole project, a WWW demonstrator will gather
the quantitative evaluations of every applications, in order to
be accessed by the scientific community, either specialist or
non-specialist of the considered applications.
The following figure is the home page of the WWW demonstrator.
The whole demonstrator could be available at ESRIN near the end
of the year.
Figure 5: Home page of the WWW demonstrator
The INSAR study is currently ending, and will propose the
first quantitative evaluation of the INSAR techniques towards
the conventionnal measurement ones for the 5 considered applications.
It is a necessary step for understanding the interferometric market.
- Tarayre Hélène, 1996 a:
- Extraction de modèles numériques de terrain
par interférométrie radar satellitaire, algorithmie
et artéfacts atmosphériques. PhD Thesis, MCS
- Tarayre Hélène, 1996 b:
- New methods of phase unwrapping and baseline adjustments in
SAR interferometry &
Atmospheric artifacts on interferograms FRINGE 96.
- Massonnet Didier, 1996:
- Description of the DIAPASON software developed by CNES:Current
and Future Applications. FRINGE 96.
- Lefauconnier Bernard, 1995:
- Glacier flow measurements in Spitsbergern, Svalbard, from
differential interferometry FRINGE 96.
- Askne Jan., 1996:
- Forest INSAR decorrelation and classification properties.
- Dammert Patrick, 1996:
- Accuracy of INSAR DEM measurements in forested areas. FRINGE
- Small David, 1996:
- Validation of height models from ERS Interferometry FRINGE
- Rott H, 1996:
- Glaciological studies in the Alps and in Antarctica using
ERS interferometric SAR FRINGE 1996.
- Briole Pierre, Massonnet Didier, Delacourt C., 1996:
- Post eruptive deformation associated with the 1989 lava flow
of Etna detected by radar interferometry. To be submitted in:
Geophysical Research Letters, August 1996.
- Feigl Kurt L., Dupré Emmeline, 1995:
- RNGCHN: a programm to calculate displacement components from
dislocations in an elastic half space. To be submitted in: Computers
and Geosciences, September 1995.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,