Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986
Insertion of hydrological decorralated data from photographic
sensors of the Shuttle in a digital cartography of geophysical
explorations (Spacelab 1-Metric Camera and Large Format Camera)
G.Galibert
Equipe Aerogéographie, Rennes, France
'ABSTRACT :Microphotographie enlargements of space imageries from the Shuttle (Metric Camera and Large Format
Camera are.combined with digital maps from airborne sensors in order to realize flight documents (actual)
for different aerial geophysical surveys through various data transmission networks using the Telecom 1 and
the Inmarsat satellites.
RESUME;Dee agrandissements de microphotographies d'images spatiales en provenance de la Navette (Chambre Métri-
aue .et Chambre de Grand Format^sont combinés avec des cartes digitales acquises au moyen de capteurs aéroportés
en vue de réaliser des documents réellement utilisés en vue de la navigation lors d'opérations géophysiques
aériennes mettant en oeuvre différents réseuax de transmission de données par le ! satellite Télécom 1 ou le sys
tème Inmarsat,
1 NEW PRODLEMS ARISING IN THE FIELD OF NAVIGATIONNAL
PREPARATION OF AERIAL GEOPHYSICAL SURVEYS
The use of head-up displays navigationnal aids,during
aerial geophysical surveys allow to superpose on the
airborne TV monitors synthetic images to the actual
landscape and to the digital localization of planes
and helicopters :for example in the Syledis System
from Sercel-CGG,which gives an accuracy of+ or- 2 m
in X and Y from ground based stations.
These problems do not arise aboard of the planes when
displays at the high rate of 1.2 ¡-¡pixels - 8 bits
per second are currently processed.They arise during
field operations of preparation when in-situ data
and digital data from the central or overseas offices
are integrated with very short allowed delays.
Difficulties occur when important data flows from
satellites,for example th~ french Telecom 1 system
(ground mobile stations with flow rates of 64 Kbits
or 1.92 Mbits per second ) are linked to one or more
ground or off-shore based stations with possible
data flow rates of 300,1200,2400 or 4800 bits per se-
con.Same problems arise when ground mobile TV stations
for analogical TV using the Telecom 1 satellite sys
tem are linked to central offices of geophysical
companies.
In fact,the unique solution to such a problem is to
realize the most important compression of data during
all sensings and processings and to use the lowest
flow rates,even 110 bits per second if necessary,more
currenttv: 800 or 1200 hits per second,with the same
speeds 01 uraitfemission wnen expressed in bauds.
Vie will examine the problems of data compression from
the Shuttle photographic imagery,which give a good
cartographical generalization to surveyors.
2 RESOLVING POWER AND CARTOGRAPHICAL GENERALIZATION
FROM METRIC SPACE PHOTOGRAPHS
We will compare actual possibilities from two lots
of photographs : two infra-red 2443 false-colour pic
tures and one black and white XX positive Kodak first
copies from the Metric Camera experiment (2 and 5-12
December 1983),and two black and white 3414 Kodak
positive first copies from the Large Format Camera
experiment (11-11-1984).
2-1 Metric Camera imagery
The absence of an image-movement compensation system
on the Metric Camera from Zeiss (Fed.Rep. of Germany)
is not an important disadvantage in such a field of
application.
The following images were analyzed : n°271 IR Color
(Brittany,south side of the Channel) date: 02-12-83
centre :48.2 N,001.7 W.№ 873 B.and W.(hattmark Dam
Switzerland),date 05-12-83,centre 45.7 N,007.9 E.The
sun elevations were comparable :19°-11«05 GMT and
15° - 09.00 GMT.
After a magnification of 10 times (linear) of the copy
a quasi negative print at the scale of 1/61500 approxi
mately on the actual publication (see fig.2)was Eeallyi
used during a short test of area navigation.
The reference image,from the LFC is the figure 1 at the
scale of 1 : 274200 approximately.
We see(arrow)the contact between the Mattmark Dam
and the rocky west side ofthe valley which is useful
in order to check and calibrate the forward down loo
king radars.
The structure of the Spacelab 1-MC images is very
propitious to fine measurements using texture analysis
of the photograph (Galibert,1985)•
The groups of agglutinated crystals are comparable
to elementary cells of terrain analysis (Light,1986):
between 3 and 10 micrometers for the black crystals,
between 10 and 15 micrometers for the blue crystals,
20 to 60 micrometers on the first copies from DFLR.
Vie confirm the wonderful accuracy of length measure
ments along the track or across the track on MC images.
In spite of an image-motion of 7,7 m along the track
per millisecond of the shutter-speed,we obtained the
following accuracies across the ground track and in a
parallel direction to the track :
across the track :
Quay of Duguay Trouin dock-Harbour of Saint-Malo.
actual length : 467.5 m.
measured length between orange crystals : 445*0 m.
difference : 22.5 m.
along the track :
Run-ways of Rennes-airport.
The width were measured between the green crystals
of the Color IR first copy.
Main run-way.
actual width between the grass fields : 52 m.
Width on the MC photograph,which is visible between
the agglomerated green and orange crystals :
49 m (the authorized width for take-off and landing
is 45 m.
Difference : 3 m.
Unfortunately such an accuracy is conditionned by the
contrast of the ground-objects.
