19 
ansparencies 
al and 
The 
if the 
arged to the 
inner 
»nsity 
le different 
It is possible to select different colour tones (hues), given by a 
fixed ratio of the three signal amplitudes (ratio mapping, clustering). 
From one channel the quantization of the gray levels or an equidensities 
display can be made. 
Details of these procedures are explained with the following examples 
for land use classification from an ERTS scene in Bavaria. For further 
information of the instrument and programming see bibliography. 
The display of the results is made on colour film, using colour coding 
of objects. A reproduction in this paper is not possible} colour slides 
are available from the author. 
further 
RESULTS 
> • 
scanning 
Leal ground 
:tures 
The separation of surface water from other details is possible by 
density slicing in the channel MSS 7. In this channel the water appears 
dark by the low infrared remissivity. The density level for the 
separation of water had to be set very carefully. For small lakes and 
»lour 
a 
t 
ponds the contrast is reduced because of the limited spatial resolution 
of the MSS and photographic processes. In spite of this, lakes and ponds 
are detectible , which have dimensions smaller than the theoretical 
resolution. For some cases an enhancement of lines and edges, using 
high pass filtering, is necessary to get surface water areas more sharply 
outlined against other objects. Normally, small rivers do not appear 
in the picture. By setting the density discrimination level to lower 
values, the rivers are visible, but then other details, namely urban 
areas appear in the picture. 
:ied 
The same problem occurs for the classification of water by its blue 
colour in the colour composition. Here the clusters of urban areas and 
water are not fully separated in the colour space. 
enlarge- 
the 
For greater lakes and the coastal region of the ocean the water depth 
can be determined by the density in the channel MSS 4, provided the 
water is clear and not polluted. It is possible to map the water depth 
ire 
ttern 
ial by 
ion 
lied to 
graphs, 
down to 20 m using equidensities display. 
For vegetation classification a colour composition similar to the false 
colour film is used. The vegetation appears in different red colour tones. 
Normally, in the colour composition the MSS 7 is copied with red, MSS 5 
with green and MSS 4 with blue light. A similar result is gained with 
a two-colour composition, copying MSS 7 in red and MSS 4 in cyan (blue-green) 
For vegetation analysis these two colour compositions are equal. This 
ions 
d for 
d out 
in 
om 
shows that MSS 5 (and MSS 6) is of linear dependance from MSS 4 and MSS 7. 
Before making an operational analysis of the vegetation with the colour 
scanner, a cluster diagram was made. For samples of known vegetatidn 
objects the three colour densities are measured. Each triple of densities 
represents a vector in the colour space. For vegetation the colour space