Figure..il°10 :Actual synthetic document. . 
Insertion of decorralated data in a digital repre 
sentation of the terrain with correlated geophysi 
cal recordings. 
Area of Tremargat,close to Rostrenen (Brittany-Fran- 
ce). 
The curves (a),(b),(c),(d),(e) and (f) can be neg- 
]{jted,they are visualizations of geophysical parame 
ters . „ . 
1 1 
Upper section : 0 X is a scale of horizontal lengths. 
1^division : 100 meters. ^ 
0.Y scale of raster representation.equal to OX. 
0 Z scale of heights : 8 times O'x'. 
GPI 1 can be neglegted (navigationnal way-poin^. 
Lowest section : Vectorial representation of remote 
sensing parameters. 
The italic characters can be neglected(air use only) 
3 ACTUAL INSERTIONS OF RFMOTE-SENSING DATA.FROM 
SPACE PHOTOGRAPHICAL IMAGERY IN DIGITAL DOCUMENTS 
3.1 Compression of data using a digitalization of 
colours. 
We present a combination of raster'descriptions of the 
Terrain through elevation profiles (DTM) and vecto 
rial descriptions of the significative colours of the 
ground objects or of aerial colour photographs. 
16 bits per field (cell) of Terrain analysis are 
sufficient for a mapping with a 3 m (10 ft) contour 
interval accuracy,common for 1/24000 or 1/25000 scale 
maps. 
Please see the figure n° 10 : GPI 1 (upper section) 
symbolyzes a portion of the Terrain (morphology) using 
a raster tepresentation. 
The scale of the appearant colours of the Terrain 
\,or a colour aerial photograph) with a standard illu 
mination (for example the international Standard D - 
6504 °K) is expressed using radiometric measurements 
through selected filters ;on the left part of the fi 
gure n° 10,lowest section,the vectors (A),(3) and (0) 
express the relative percentage of energy of the fil 
tered specific radiations,for example through classi 
cal Wratten filters 12 (yellow),25 (red) and 47 (Blue) 
with the superposition of. a"cold mirror" cutting the 
photographic infra-red radiations over 0,9 micrometer. 
We realize an important compression of data when we 
sense or when we store or transmit two only (A 
and B for example) of the radiometric measurements 
considering that the total percentage is a constant. 
Furthermore,the use of selected filters,with two 
channels,give a bichromatic image of the object (Ga 
libert,1976).These measurements give directly two 
digital parameters.of colours which are decorralated 
of the original colours (vectors AA and BB,right 
side of the lowest section ,figure n° 10).They are 
also decorralated of the three trichromatic parame - 
ters which are commonly used.AA is used(sum of A andB) 
When colour'pictures- are digitalized using a 4 bits 
encoding,expression of 2^ colours,a total of 20 bits 
per cell (pixel) of Terrain analysis is is sufficient 
in order to superpose such an imagery to' radar and vi 
deo images or cartographical representations of the 
Terrain,in order to prepare special geophysical 
flights using head-up displays navigationnal aids. 
3-2 Pre-flight data.Problems of storage and daily 
transmission from central offices to field bases. 
The above mentionne! problems- request to transmit, 
using digital methods,the characteristics of 2 diffe 
rent surfaces : topographic (GPI 1) and colour repre 
sentation which are respectively expressed through 
raster and vectorial 'ends of vectors) methods C6-PI1). 
We will examine an actual test-case of a geophysical 
air-strip which is a kind of provisionnai airway, 
with two side-limits for airborne sensings of magne- 
tometry for example : 
Length : 1200 Km.Width : 3 Km.Such a strip can be 
divided into parallel lines for cell(pixel) analysis 
from a plane or helicopter or from preflight docu 
ments . 
Table 1.Digital data volume of a cell analysis of 
the' Terrain . 
Dimensions of cells 
Number of cells number of lines volume of data(bits) 
per line 
3m 
1098 
10m 
300 
25m 
120 
439 
500 
7.7 
Gbits 
120 
098 
2.1 
Gbits 
CO 
039 
0.84 
Gbits 
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The maxima: 
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»atex'trans: 
REFERENCES 
All photog 
n° 6 (P.Y. 
(P.Y.Galib 
Galibert, 
tion bio 
168. 
Galibert, 
que dans 
Geog.Alp 
Galibert, 
analytiq 
en vue d 
16 et 17 
Galibert, 
offshore 
Proc.DFV 
Light, D.L 
tal mapp