TEACHING RASTER GIS OPERATIONS WITH SPREADSHEETS

Many universities are introducing courses to teach students the princi ples of geographic information systems (GIS). In addition to lectures, exercises with commercial GIS software are offered to show basic oper ations. Although students learn to execute such operations, the softwa re may hide their internal structure and logic. We propose using a spr eadsheet program as a teaching tool for raster operations such as filt er and overlay. Spreadsheets offer a practical way to demonstrate and experiment with raster operations, because the raster structure is cap tured in the form of rows and columns. With this tool, students are ab le to perform and visualize operations as well as to see how the data are processed by the algorithms. Our approach is new in that we concen trate on the algorithms of operations. We make explicit which raster f unctions are actually evaluated when performing a particular operation , We conclude that there art: good reasons for using spreadsheets in c omparison to traditional GIS software when teaching raster operations. These are demonstration in class, simple user interface, familiarity to students, low cost, flexibility of changing cell values, ease of ch anging parameters, easy programming environment, and the possibility t o look behind the scenes of operations by viewing the code.