3.5 Forestry Mapping of Northern Namibia
A forestry mapping project made in co-operation between SSC
and the Directorate of Forestry under the Ministry of
Environment and Tourism of Namibia of the forestry areas of
Northern Namibia started in late 1992 and finished in late 1994.
Forestry Maps based on 46 Satellite Image Maps at 1:100,000
based on Landsat TM and 158 Satellite Image Maps at 1:50,000
based on SPOT multispectral were produced. The middle
infrared channel of Landsat TM was not used as it was not
considered, after tests, to contain any additional information
compared to the conventional infrared colour combinations.
The project has now been extended to a second phase, mapping
24 more map sheets at 1:100,000 and 92 map sheets at 1:50,000
with similar methodology.
3.6 Land Use / Land Cover Mapping in Mongolia
The project entitled "The Assessment of Environmental
Conditions and Land Use / Land Cover Mapping of the Ugtaal-
Jargalant Area" was carried out as a co-operation between SSC
Satellitbild, the Research Institute for Land Policy and the
National Remote Sensing Centre in Ulanbaatar during 1994-95
(Malmberg et al, 1995). The project was based on one set of
SPOT XS scenes from 1994 and one provisional set from 1986,
in which a gap was complemented with Landsat TM data.
Precision corrected Satellite Orthophoto Maps at 1:50,000 and
1:150,000 were used for visual interpretation of 16 area classes
and 7 point and land feature classes. The work flow is described
in Fig 5.
Activity Flow Chart
Reception of SPOT Data at SSC Esrange
and of Landsat TM Data at EROS Data Centre, USA
|
Collection of Maps and Documents
|
Production of Digital Terrain Model (DTM)
|
System and Precision Correction of Satellite Data;
Enhancement of Contrast and Colour Balance;
Production of CD-ROMs of SPOT XS Scenes
Production of Photographic Images of SPOT XS Scenes,
Scale 1:100,000
|
Digital Mosaicking and Sectioning of Satellite Scenes
combined with Digital Terrain Model into
Satellite Orthophoto Maps (SOMs);
Production of CD-ROMs of XS and TM SOMs
Production of Photographic Images of TM SOM, Scale 1:150,000
Production of Photographic Images of XS SOMs, Scale 1:50,000
|
Study of Background Material
|
Ground Field Work
|
Training in Sweden
|
Definition of Preliminary Classification Legend
|
Draft Interpretation
|
Field Work
|
Definition of Final Classification Legend
|
Final Interpretation
|
Digitizing of Interpretation Manuscripts into a
Geographic Information System (GIS);
Area Computation
|
Digital Cartography
Plotting of Printing Originals for Land Use / Land Cover Maps,
Scale 1:50,000
|
Printing of Land Use / Land Cover Maps
|
Final Report
Figure 5. Activity Flow Chart for the Assessment of
Environmental Conditions and Land Use / Land
Cover Mapping of the Ugtaal-Jargalant Area.
3.7 Forest Inventory in Chile ( À Pilot Project)
The aim of the project was to (i) evaluate whether the use of
satellite images can fulfil, completely or partly, the demand for
up-to-date forest information on both plantations and native
forests; (ii) evaluate feasible data sources to be used and (iii)
evaluate technology to be used - digital or analog. The goal of
the project was to test the feasibility and learn how to use
satellite data in forest inventory. It was carried out as a co-
operation between SSC Satellitbild and Instituto Forestal in
Santiago de Chile. Seven natural forest types and five plantation
classes were available within the project area.
Today the inventory of the plantation forests is done using
aerial photographs for later transfer into GIS - the scale
corresponding to 1:50,000. Concerning natural forests overall
up-to-date information is mainly lacking, but is now carried out
at scales corresponding to 1:250,000. Three test areas were
inventoried - each covering four different map sheets at
1:50,000, and including one sheet at 1:25,000 - one coastal
area, dominated by pine plantations, and two mountainous
areas, consisting mainly of secondary and primary natural
forests. Satellite Orthophoto Maps were produced for the
corresponding map sheets based mainly on merged SPOT
panchromatic and multispectral images. Landsat TM was used
complementarily. Digital interpretation on hard copies and
semi-automatic computer based methodology were compared.
In the latter method, the images were segmented automatically
and a predelineation was achieved. This predelineation was the
basis for an interactive delineation. In the final delineated
image, an on-screen interpretation was performed.
The results were in most regards negative for the computerised
methodology. It gave lower accuracy, and was slower and more
monotonous. Satellite data was found to be useful, but needed
to be combined with other information sources.
3.8 Planimetric Mapping for the National Population
Census in Nigeria.
As a part of the National Population Census of Nigeria, in all
177 planimetric maps at 1:50,000 were produced (Atilola,
1990). The areas to be mapped were not earlier covered with
sufficient 1:50,000 maps. Where maps existed they were
produced by approximate means which included direct tracing
from aerial photographs and acquisition of control points by
slotted templates. For five out of seven blocks SSC produced
Satellite Image Maps (not orthocorrected) from multispectral
SPOT-images. The choice of the multispectral mode was based
upon image availability. The Satellite Image Maps were
produced in UTM, while most of the existing material was in
Modified Transverse Mercator in imperial units.
From the Satellite Image Maps cartographic information was
extracted and later verified in the field - primarily settlements
and road network. The results were presented as combined line
and image maps in black and white. For the relatively limited
selection of objects to be detected the project was considered a
success. SPOT data existed for almost the complete areas,
which was in itself a success as some mountainous areas had
earlier defied all attempts to be mapped because of cloudiness.
This mapping resulted in a continuation with updating of the
regular 1:50,000 series by the Federal Survey Department of
Nigeria of further 350 map sheets, this time using panchromatic
images (Allo, 1993).
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996
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