Overview maps
General overview maps can be
created from very high resolution data sets to cover a specific area.
General cartographic information can be portrayed and feature extraction
can be performed to transform features in a high resolution satellite
images to vectors. This can be especially relevant for extracting
features such as roads, buildings and other structures in order to
perform GIS analyses or to update or perform quality checks on existing
map data.
Land Cover / Land Use Mapping
A satellite image
often contains information that can readily be analysed visually. In
most cases it is possible to get an idea about the relative importance
of urban areas, forests, agriculture etc. just by looking at the image.
Nevertheless, it is in some cases necessary to convert the satellite
image to a thematic map of different land cover or land use types. This
will make it possible to work quantitatively with the characteristics of
the area and to analyse and understand the distribution of different
land cover types.
When converting a satellite image to a thematic map of land cover
classes it is possible to perform simple calculations like the overall
area of each class. However, more detailed analyses can generate a
deeper understanding of the area, i.e. by looking at the degree of
fragmentation of the area or the distance from a specific class to a
specific feature. With this information it is then possible to analyse
how far deforested patches in a tropical forest area are located from
roads or settlements, or to analyse which agricultural crops are grown
on the steepest slopes.
Change detection
Using time series of satellite
images, it is possible to calculate the degree of change between
predefined land cover classes. In this way, changes in the areal extent
can be calculated over time. For instance, a typical task would be to
determine how significant the deforestation rate has been in tropical
forest region and to examine what land cover class the forest has
changed to. These analyses can be combined with GIS modelling to predict
future scenarios.
Applications
Typical applications of land cover
mapping are for instance: 1) generating input for hydrological models 2)
analysing environmental degradation or ecological stability or 3)
updating agricultural statistics such as crop types, fallow periods etc.