GEOGRAPHIC INFORMATION SYSTEM (GES203) GIS Components Level 2:1 By: Mrs Mupfiga
Presentation Layout Recap Learning Objectives Components of GIS GIS Data References Lecture Evaluation
Learning Objectives To identify the 5 basic components of a GIS To describe the basic components of a GIS To describe geographic data To identify the sources of geographic data To describe the GIS Cycle
Recap What is so special about GIS? Where can GIS be applied?
GIS Components
People People are the most important part of a GIS because they define and develop the procedures used by a GIS GIS technology is of limited value without the people who manage the system and develop plans for applying it to real-world problems. Ground truth data collection Data storing, processing and analysis GIS users range from technical specialists, who design and maintain the system to those who use it to help them perform their everyday work.
Approaches / Methods/ Organizational protocols. A successful GIS operates according to a well-designed plan and business rules, which are the models and operating practices unique to each organization
Hardware Hardware is the physical components on which a GIS operates CPU Monitor Digitizing table Scanners Printers What are the hardware specifications for GIS?
Hardware GIS can be run on a wide range of hardware types, from centralized computer servers to desktop computers used in stand-alone or networked configurations. A fast computer, large data storage capacities, and a highquality display. A fast computer is required because spatial analyses are often applied over large areas and/or at high spatial resolutions and calculations often have to be repeated over tens of millions of times, In GIS large volumes of data must be entered to define the shape and location of geographic features, such as roads, rivers.
Hardware For presentations, a printer and a projector are needed Digitizing tables and scanners are needed to convert analogue map data and tables to digital databases It is important to adapt the investments in hardware to the needs of the organisation. All system components need to be connected in a Local Area Network (LAN) if maximum efficiency should be reached in a complex organisation.
Software GIS software provides the tools to capture, manage, analyze, and effectively display spatial data and spatial information. There are many public domain and commercially available GIS software packages, Many of these packages originated at academic or government-funded research laboratories. List the GIS software that you know. The GIS software often represents a considerable share of the investment costs when introducing GIS in an organisation.
Software It is important to consider the needs, the user category and the functionality, since it is rather useless to provide a person with very limited knowledge in GIS an advanced software and vice versa. Thus to optimize the investment software must be adapted to the activities of users in the organization Another important issue to consider when selecting software is the possibilities to get technical support from national suppliers rather that being dependent on support from organizations overseas.
Software Examples of the major or widely used software packages are ArcGIS, ERDAS (Earth Resources Data Analysis System, used for Remote sensing image processing e.g is ERDAS IMAGINE 9.1), ILWIS(mostly used for hydrological modelling), QGIS Grass (Geographic Resource Analysis Support System), Mapmaker
Data Is the fuel of the GIS. Data can be collected inhouse or purchased from a commercial data provider. This means that the information must be from a reliable source. It must be accurate record of reality. The suppliers of data must have a reliable rate of supply.
Data Data must carry with it quality statements about how the data was collected, by whom and when etc. this information guaranties / verifies the quality of the data. Data must be relevant for the purpose for which it must be used. It must be the correct type of data. Data must be accessible. This is a big issue in most developing countries.
Data No matter how sophisticated a GIS may be, it cannot change the fact that the system is never better than its weakest link. If a GIS is fed by garbage data, the output from analysis and other operations will also be garbage
Video Components of GIS
GEOGRAPHIC DATA
What is geographic data? Data that can be allocated a location, It is necessary to define what geographical data is, since GIS operates by using this type of data. Geographic data includes all things on the earth s surface. Geographic data = Geometric data + Non Spatial data (attributes/properties) Geometric data: gives the location data and spatial extent (shape) of map objects. Attribute data: represents some property that describes the map objects.
Almost all objects in our surroundings can be connected to a specific location and are possible to handle in a GIS.
Geographic Data describe
Geometric data Location is given by using a coordinate system.
Non spatial data: Attribute data Attribute data is the non-spatial data about a geometric object Attributes describe the characteristics of the map objects and are linked to these objects in the GIS Examples?? Object Road Attribute Road No. ; Surface type, Width, House Owner, Address, No of rooms Administration district Name of District, Population
Geographic Data
Demonstration Hardware Software Geometric Data Attribute Data
Homework: Attribute Data Types Describe giving specific examples, the following attribute data types: Nominal Ordinal Interval Ratio [15]
Metadata Information about data Acts as quality statement. It assures a certain level of quality, reliability and flexibility for the users of the database Description of the source of data and the database development process information about where the data was retrieved from and how it has been processed before entering the database. Attribute accuracy Is the attribute an actual measurement, estimation or interpolation of attribute values.
Metadata Date(s) of data collection and interval of updating the data. - It is important as it informs the user about future extensions of the database. Some databases, e.g. census data, may be valid for a certain time span, which should be indicated in the metadata. Name and owner of database, The projection, co-ordinate system, map datum Completeness is the information true for the whole area covered by the database or are there differences in quality, temporal accuracy, consistency,etc.
Functions of a GIS Capture GIS data, Storage of data, Analysis of data, Visualization of GIS data, presentation of GIS analysis products,
Next Lecture Vector Data Model Raster Data Model
References DeMers, M N, 1997, 2003, 2005, Fundamentals of Geographic Information Systems (1 st, 2 nd or 3 rd edition). John Wiley, New York. Heywood I, Cornelius S, Carver S, 1998, 2002, 2006, An Introduction to Geographical Information Systems (1 st, 2 nd or 3 rd edition). Addison Wesley, Harlow. Longley P A, Goodchild M F, Maguire DJ, Rhind DW, 2005, Geographical Information Systems and Science. (1 st or 2 nd edition). Wiley, Chichester http://www.rst2.edu/ties/gentools/comp_gis.html http://map.sdsu.edu/geoagent/gis_intro.htm