Quantity Surveying: Global Information System
Global Information System (GIS) is a system of hardware and software used for storage, retrieval, mapping, and analysis of geographic data. GIS also includes the operating personnel and the data that go into the system.
Spatial features are stored in a coordinate system, which references a particular place on the earth. Descriptive attributes in tabular form are associated with spatial features. Spatial data and associated attributes in the same coordinate system can then be layered together for mapping and analysis. GIS can be used for scientific investigations, resource management, and development planning.
How GIS Differs
GIS differs from CAD and other graphical computer applications in that all spatial data is geographically referenced to a map projection in an earth coordinate system. For the most part, spatial data can be "re-projected" from one coordinate system into another, thus data from various sources can be brought together into a common database and integrated using GIS software. Boundaries of spatial features should "register" or align properly when re-projected into the same coordinate system.
Another property of a GIS database is that it has "topology," which defines the spatial relationships between features. The fundamental components of spatial data in a GIS are points, lines (arcs), and polygons. When topological relationships exist, you can perform analyses, such as modeling the flow through connecting lines in a network, combining adjacent polygons that have similar characteristics, and overlaying geographic features.
Applications of GIS
Among the earliest and still most widespread applications of the technology are land information and resource management systems.
Other common uses of GIS in an urban policy context include:
- emergency planning;
- determination of optimal locations for fire stations and other public services;
- assistance in crime control and documentation;
- and electoral and school redistricting.
Spread of GIS Applications
Uses of GIS have spread well beyond geography, the source discipline, and now involve most applied sciences, both social and physical, that deal with spatial data. The nature of the applications of GIS in these areas ranges from simple thematic mapping for illustration purposes to complex statistical and mathematical modelling for the exploration of hypotheses or the representation of dynamic processes.
Advantages of GIS in Quantity Surveying
The advantages of using a geographic information system include:
- Easy decision making process: Application of GIS makes decision making process easy through presentation of specific and detailed information about one or more locations.
- Reduced costs and increased efficiency: GIS enables cost-effective and efficient maintenance schedules, fleet movements or scheduling timetables.
- Improved communication: The easily understandable visual format of GIS enables efficient information sharing and dissemination between organisations or departments.
- Easy recordkeeping: GIS records geographical changes easily so that the work of those responsible for recording the changes will be easy.
- Easy geographical management: GIS helps experts to have prior knowledge of what is and will be occurring in a geographic space so as to plan a course of action.
Critical Tasks in Designing GIS
Critical tasks in designing global information systems are:
- Process and system design: How are the processes between distributed actors organized, how are the systems distributed / integrated.
- Technical architecture: What is the technical infrastructure enabling actors to collaborate?
- Support mechanisms: How are actors in the process of communication, collaboration, and cooperation supported?
Stemming from the critical tasks, in designing GIS, a variety of examples can be given. Basically every multi-lingual website can be seen as a global information system. However, mostly the term GLIS is used to refer to a specific system developed or used in a global context.