n
SPOT IMAGE
| Select intrested areas 3]
Preliminary operation on 2B level
Raster image in
UTM Projection
Classification
[Theme 1 / [ Theme 2 / eins [Themen |
Data homogenisation
Y
Data export into GIS
Vectorisation
+
Real world
Transformations using
some GCP
Figure 2.Integration of SPOT images
The second stage of the integration procedure is the
image classification. As there are two main natural
environmental types, each one having an important
variety (vegetation and water), within the Danube Delta,
firstly, vegetation information should have been masked
not to influence water classification. Naturally, the
Danube Delta aquatic vegetation is prevalent; therefore a
proper precise separation between the water and
vegetation plans was rather difficult. The same separator
operations have been done when 1992 image was used.
The third stage of the integration procedure is to make
classification image to be homogeneous (Ducamp,1991).
During this procedure, the image legibility coefficient
could be improved after reducing the number of the
isolated pixels, i.e. polygon reductions after vectorial -
like operation has taken place. It is quite difficult to get
807
the best legible level because a too homogeneous
information accomplishment entails removals, as well.
Just an example: a hydrographic grid could lose the
continuity due to its refinement. A small channel is
represented on a classified image as a pixel array without
being always well linked. Applying a "rude"
homogeneity the channel pixels could be easily lost.
Such an error could distort some analysing types. On the
other hand a little homogeneity forth rather many
isolated pixels. So, the image could not be analysed
properly and clearly.
The fourth stage of Remote Sensing information
integration procedure is to get vector - like classified
images.
This operation includes raster - module image change (a
large storage consumer) into - module one (more
economic as regards storage). More than that, vector -
module is more suitable for the complex graphical
processings and topologic implementations.
The fifth stage (the last) of integration is overlapping the
resulted plan over the other ones (information layers).
The channel hydrographic grid was considered a basis
and the channel intersection were used as control points
in this operation.
4. PRELIMINARY INTERPRETATION OF
INFORMATION OF THE DATA BASE
Analysis and Conclusions on the Floating Island
Dynamics.
(A) To identify stable elements of the "natural
patrimony", we have used a proper procedure removing
dynamic elements/phenomena. Such a phenomenon is
shown by "floating reed islets" (floating islands) made of
vegetation and soil sometimes covering almost dozens of
ha. In their removal, we have used an algebraic
operation linking the floating reed islets derived from
1990 and 1992 images, called LAC90 and LAC92. To
get the new attributes, we have used the following
commutative rules:
LAC90 + LAC92 = 900R92
water90 + water92 = water
vegetation90 + vegetation92 = vegetation
vegetation90 + water92 = water
water90 + vegetation92 = water
Rule 1 :
This new plan contains a stable condition of the soil
cover as against the first classification level. On the other
hand, if we want to investigate these floating reed islet
evolutions, a new plan could be set up based on the
linking operation but using a bit different commutative
rules:
Rule2: LAC90 + LAC92 = 90AND92
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996