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Tutorial 5 introduced the concept of Cartographic Modeling and Database Query using the modules ASSIGN and RECLASS and OVERLAY. We will continue to explore the manipulation of raster images to produce desired results. This exercise will consist of tutorial 6 from the Idrisi for Windows Student Manual and will involve the expansion of the Boolean operations introduced in the last exercise to a more general case governed by the rules of Map Algebra . In this exercise, for the first time, you will not be given all the basic images needed to complete the exercise, but instead will learn how to produce the required images for the analysis by deriving them from other data. In the process, you will discover how to use four new modules: TRANSFOR, SCALAR, REGRESS, and CROSSTAB.

The problem posed involves producing an agro-climatic zone map for the Nakuru District in Kenya, which lies in the Great Rift Valley of East Africa. An agro-climatic zone map is a basic means of assessing the climatic suitability for growing certain agriculture crops. Agro-climatic zones are defined as specific combinations of moisture availability zones and temperature zones. However, neither of the maps for moisture availability zones or temperature zones exists. What we do have is: 1) a mean annual rainfall image called NRAIN, 2) a digital elevation model named NRELIEF, and 3) tabular temperature and altitude data for nine weather stations. In the course of producing the final images, you will apply the rules of Map Algebra which refers to the use of images as variables in arithmetic operations.

For more information on these concepts, refer to the Idrisi Tutorial on WWW at:



  • and to the On-line Help available within the Idrisi software itself.


    With the supervision of your lab instructor or lab coordinator, use Idrisi for Windows software to carry out the directions for Tutorial 6 in the Student Manual.


    The data for this tutorial is located in the Idrisi for Windows sample exercise data directory., typically C:\EXERCISE. The path may vary from PC to PC, so check with the instructor or lab coordinator.

    Report Format

    For Tutorial 6 on Map Algebra, answer questions 1 through 7. Prepare your answers in Microsoft Word format. Produce a printed copy of your answers for your records.

    File Final Report

    For University of Hartford students, send your Word -formatted answers to the questions in Tutorial 6 by way of e-mail to:

    For students at UConn, submit your work to:

    (Who needs) Extra Work (?)

    To reinforce the principles learned in Tutorial 6, you may do Optional Problem 1 and submit the answer to question 8 along with 1-7.

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