- “GIS is a computer system capable of assembling, storing, manipulating, and displaying geographically referenced information, i.e. data identified according to their locations.”
- “A GIS is an organized collection of computer hardware, software, geographic data, and personnel to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information.”
- Data Capture- Data sources are mainly obtained from manual digitization and scanning of aerial photographs, paper maps, and existing digital data sets.
- Database Management and Update- Data security, data integrity, and data storage and retrieval, and data maintenance abilities.
- Geographic Analysis- The collected information is analyzed and interpreted qualitatively and quantitatively.
- Preparing Result- One of the most exciting aspects of GIS technology is the variety of different ways in which the information can be presented.
- Data Capture- The input of data into a GIS can be achieved through many different methods of gathering. For example, aerial photography, scanning, digitizing, GPS or global positioning system is just a few of the ways a GIS user could obtain data.
- Data Storage- Some data is stored such as a map in a drawer, while others, such as digital data, can be as a hardcopy, stored on CD or on your hard drive.
- Data Manipulation- The digital geographical data can be edited, this allows for many attribute to be added, edited, or deleted to the specification of the project.
- Query and Analysis- GIS was used widely in decision making process for the new commission districts. We use population data to help establish an equal representation of population to area for each district.
- Visualization- This represents the ability to display your data, your maps, and information.
- Advantages of Vector
- Good Representation of data.
- Use small file size.
- Accurate map output.
- Disadvantages of Vector
- Complex data structure.
- Expensive technology.
- Analysis is complex.
- Advantages of Raster
- Simple data structure.
- Cheap technology.
- Analysis is simple.
- Same grid cell for several attributes.
- Disadvantages of Raster
- Large data volume.
- Inefficient use of computer storage.
- Difficult network analysis.
- Less accurate or attractive maps.
- Loss of information when using large cells.
Advantages of GIS
- GIS allows us to view, understand, and visualize data in many ways that reveal relationship, patterns, and trends in the form of maps, globes, reports, and charts.
- A GIS helps you answer questions and solve problems by looking at your data in a way that is quickly understood and easily shared.
- GIS give the accurate data.
- Better predictions and analysis.
Disadvantages of GIS
- Excessive damage in case of internal fault. Long outage periods as repair of damaged part at site may be difficult.
- Expensive software.
- Integration with traditional map is difficult.