Page 140 - Digital Analysis of Remotely Sensed Imagery

110 Cha pte r F o u r

Another way of interfacing with individual modules is via the
Macro Modeler (Warner and Campagna, 2004). It enables the user to
develop and link a sequence of image analysis routines to achieve
higher efficiency and to enhance workflow. Complex and repetitive
analysis is thus sped up. Only the datasets need to be modified if the
same analysis is attempted for a different area. This is very significant
because IDRISI requires a number of processing steps to accomplish
a single analytical task. Through this modeling environment, a num-
ber of processing steps can be fulfilled by clicking one button. With
such a graphic and intuitive macro modeler, the user does not need to
have any programming background in building a model. However, it
is not possible to access the image processing modules via the Macro
Modeler.

4.1.5 Documentation and Evaluation
Clark Labs provides a comprehensive online document titled “The
Guide to GIS and Image Processing” in the PDF format. Included in
this guide of more than 300 pages are both basic and advanced image
processing topics. Beginners may find a lot of the advanced topics
intimidating, and may wish to study them only after they have
grasped the essence of image analysis and familiarized themselves
with IDRISI. Other documents that are delivered with the purchase of
IDRISI licenses include a user’s guide, a quick reference, and a book
of tutorial exercises. From the reference book the user can learn what
steps to undertake to perform a particular task. Containing descrip-
tions of image analysis functions in IDRIS, the reference book may be
useful for novice users who have not had much experience with
IDRISI. However, experienced users may find this book redundant.
In contrast, the tutorial exercises are recommended for both novice
and experienced users to learn what IDRISI can offer and to familiar-
ize themselves with running the system (Hermann, 2006). Totaling
more than 40, these exercises range from introductory to advanced,
arranged in order of increasing difficulty and complexity. Accompa-
nying the tutorial is a large amount of sample data representing a
wide variety of geographic areas and image types. In addition, IDRISI
is equipped with an excellent online help document in the HTML
format with the index function not available in the PDF file. Under
each entry is a short description of the program, the general nature
of the input and output, and additional notes on technical informa-
tion, such as the algorithms used, if applicable. The last section of the
help information is about how to run the program from the com-
mand line.
Overall, IDRISI is an affordable, very user-friendly system that
has a comprehensive range of image analysis functions with excellent
documentation. It offers the most diverse range of image classifiers
and their combined uses. Its open architecture and extensibility
through its application programming interface enables developers to