inquired from Dr. Radai whether the use of
Landsat and airphotos together would be useful.
Dr. A. Fontanel (France) answered that repeated
coverage is sometimes required to adequately
deal with the effect of vegetation. Furthermore,
it was found that the use of Landsat bands 6 and
7 viewed stereoscopically is helpful. Other com-
binations including bands 4 and 5 are also useful
depending on climatic zones and topography.
Dr. Radai added that Landsat and air photos
together may be useful in finding fault lines for
locating the best sites for ground measurements.
Mr. A. Boberg (Sweden) asked Mr. Donker why
no improvement was evident in the ”feature
space”. He replied that all information should
be used from the start and worked through.
Mr. Boberg wondered if straightforward image
interpretation might be used just as effectively.
Mr. Donker said that he found his principal com-
ponent analysis improved classification signifi-
cantly. Dr. Fontanel added that the first principal
component is a weighting (containing 70 to 80
per cent of the information) which is like a
panchromatic image of the 400—900 nm range.
The second principal component (containing
10 to 15 per cent of the information) is the sum
of bands 4 and 5 plus the difference between
bands 6 and 7. It looks like a black and white
infrared photo. It shows water detail well. An
unidentified speaker from F.R.G. remarked that
he would like to have seen color used to enhance
the principal component analysis results. Mr.
Donker replied that printing techniques available
to him were primitive and color reproduction was
difficult. Dr. Fontanel added that examples of
color rendition can be found in various NASA
publications.
Dr. Schneider closed the session by expressing
appreciation for the work done by the outgoing
President and Secretary of Commission VII and,
on behalf of Dr. G. Hildebrandt (F.R.G.), invited
all to participate in the next four years of Com-
mission VII.
Commercial Exhibition in the sports hall Otahalli.
132
