
1-3 Required Functions for GIS
The questions that a GIS is required to answer are mainly as follows :
- What is at......? (Locational question ; what exists at a particular location)
- Where is it.....? (Conditional question ; which locations satisfy certain conditions)
- How has it changed........? (Trendy question ; identifies geographic occurrence or trends that have changed or in the process of changing)
- Which data are related ........? (Relational question : analyzes the spatial relationship between objects of georaphic features)
- What if.......? (Model based question ; computers and displays an optimum path, a suitable land, risky area against disasters etc. based on model)
Figure 1.4 shows examples of questions to be answered by GIS.
In order to meet the above requirements, the following functions are necessary for GIS (see Table 1.2)
- data acquisition and pre-processing
- data based management and retrieval
- spatial measurement and analysis
- graphic output and visualization