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and Moreira |
ith AeS-1
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Ts). In SAR
rorithm. The
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: the harmful
-off between
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trimmed. To
also can be
is was made
> Swiss Jura
d open areas,
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ng the height
“Topography
1999), This
smaller. The
is sufficient,
Andreas Keim
Figure 2: Terrain-geocoded SAR scene of an area
near Solothurn with superimposed topographic map
(scale 1 : 10,000)
(© Vermessungsamt d. Kantons Bern, Switzerland)
4 MAP GENERATION
For the map production as described in this paper, two information extraction methods are applied: visual interpretation
and a supervised classification.
To accerelate and simplify map production the first step after basic data preparation is to investigate the maximum
number of distinguishable classes. This was realized by programming a classification software optimized for the high
resolution SAR data. The used input data for the software are fully geocoded SAR images and DEMs. Typical classes
of interest in topographic mapping are water,
SAR : Area
Image Selection
forest, build-up and open areas. After the user
had choosen training examples inside the
graphical user interface (GUI) for the classes
of interest an artificial neutral network (ANN)
Training Set. | ^^ : S 3
Selection : classifier is designed. The used ANN classifier
UNO : : is the well-known Multilayer Perceptrom
; ; (MLP) (Rumelhart et al. 1986). An interactive
Feature Classifier A Classification Classified Il . . fi di
Selection imus TY Cif maps component allows inspection of intermediate
QUT | S results and enables feedback to training set
selection and classifier learning, thus an online
FRE learning capability is established (Fig. 3). The
: borders of the classes of the improved final
E sd . results are vectorized, stored in individual
eda dir o Pel ours layers and outputted in DXF format. This
7 vector data can be integrated e.g. in a DTP
program or cartographic information system
Figure 3: Block diagram of the ANN classifier (CIS) and combined with the data achieved by
manual screen digitizing.
In a further step of the InNSAR processing chain the third dimension of the terrain, represented by contour lines and hill-
shading, must be produced and embedded into the map. To automatize the extraction of the contour lines from the
existing geocoded InSAR DEM (see chapter 3), a software system was developed by Schmieder and Huber (2000). Due
0 the fact, that microwaves with short wavelength’ (e.g. X-band) cannot penetrate into buildings and dense vegetation
like forests, the contour lines represent only the surface of that areas which lead to an error in height. With complex
algorithms its possible to extract that areas and correct the DEM there (Huber/Schmieder 1997). The output product is
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B1. Amsterdam 2000. 175