Environmental Engineering Reference
In-Depth Information
Chapter 17
Image Processing and Geo-Referencing
17.1
Introduction
In many applications of environmental modeling it makes sense to process images,
to read them into a MATLAB
figure for certain types of processing. In some
applications it is necessary to process the images themselves. Satellite images for
example contain information about some environmental variables. The distribution
of botanical and sometimes also of zoological species within a geographical area
can be determined by a computational algorithm based on images. Infrared images
are used as they contain information about the temperature distribution.
MATLAB
®
allows various types of image processing. Only few commands are
treated here. Trauth (
2010
) tackles the topic in much more details. For those who
need an extended functionality, Math Works offers an Image Processing Toolbox,
containing tools to analyze and visualize images, develop algorithms, and share
results; see:
http://www.mathworks.com/products/image/
.
Interested readers are
referred to the related textbook of Gonzales et al. (
2004
).
In core MATLAB
®
, the
'hdftool.m'
is available to explore, extract, and display
satellite remote sensing data sets, distributed by the National Aeronautical and
Space Administration (NASA) in Hierarchical Data Format (HDF). The reader
can view the details in the MATLAB
®
help index under the keywords 'hdf' or
'hdftool'. In this chapter these options will not be presented further.
In the following, examples are restricted to few other purposes. Imagine a map or
a cross-section plot through some environmental system. The figure contains some
valuable information about a relevant variable or parameter distribution. Using a
map the location of positions, of lines and of areas can be determined. Lakes, rivers,
shorelines, and land-use patterns are examples of such distributions which can be
located with the help of a map. A geological cross-section, in which rock- or
soil-type layers are visualized, is another example of a 2D illustration of informa-
tion. The thickness of these layers, as well as their location, represented in the cross-
sectional view, are data that the user may need to extract for modeling soil, aquifer
or geological processes.
®
