Spatial Information Technology

The One Thing

Spatial information technology connects locations on the Earth’s surface with descriptive information, enabling geographical features and their relationships to be collected, analysed and displayed. GIS, Remote Sensing and GPS are complementary technologies that support evidence-based planning, resource management, environmental monitoring and regional development.

Who and What

• Spatial Information Technology: A group of technologies used to collect, manage, analyse and display information associated with specific locations. Its value lies in analysing geographical relationships, patterns and changes, not merely locating features.
• Geographic Information System (GIS): A computer-based system that captures, stores, edits, analyses and displays geographically referenced data. GIS links spatial data, such as roads and rivers, with attribute data, such as population and land use.
• Spatial Data: Data describing the location, shape, size or relationship of geographical features.
• Attribute Data: Descriptive information linked to a geographical feature, such as the name, population or land-use type of a place.
• Map-Linked Data: Information connected to map features so that selecting a location reveals related descriptive details.
• Raster Data: Spatial data represented as a grid of cells or pixels. It is suitable for continuous features such as elevation, temperature and satellite images.
• Vector Data: Spatial data represented by points, lines and polygons. It is suitable for features such as wells, roads, rivers, districts and land parcels.
• Point: A vector feature representing a single location, such as a school, village or weather station.
• Line: A vector feature representing a linear feature, such as a road, railway, river or boundary.
• Polygon: A closed vector feature representing an area, such as a lake, forest, district or agricultural field.
• Layer: A set of related spatial features displayed together, such as a road layer, drainage layer or population layer.
• Remote Sensing: The collection of information about the Earth’s surface without direct physical contact, usually through sensors on satellites or aircraft. It can support land-use mapping, crop monitoring, forest assessment, water-resource studies, weather observation and disaster management.
• Global Positioning System (GPS): A satellite-based navigation system used to determine the location, elevation, direction and time of a receiver. GPS determines position by receiving signals from several satellites; signals from at least four satellites improve the calculation of three-dimensional position and time.
• Georeferencing: Assigning real-world coordinates to a map, image or dataset so that it aligns correctly with other spatial data.
• Coordinate System: A reference framework for identifying positions using latitude and longitude or projected coordinates. Latitude measures angular distance north or south of the Equator, while longitude measures angular distance east or west of the Prime Meridian. The Equator is at 0 degrees latitude, and the Prime Meridian is at 0 degrees longitude.
• Attribute Table: A tabular database in which rows represent geographical features and columns contain their descriptive properties.
• Spatial Analysis: The examination of locations, distances, patterns, relationships and changes among geographical features.
• Overlay Analysis: The combination of two or more map layers to identify relationships or suitable locations.
• Buffer Analysis: The creation of a zone at a specified distance around a feature, such as a protective zone around a river or a service area around a hospital.
• Database: An organised collection of data that can be stored, searched, updated and linked to spatial features.
• Digital Elevation Model (DEM): A digital representation of the height or elevation of the Earth’s surface.
• Thematic Map: A map designed to show the distribution or variation of a particular theme, such as rainfall, literacy or crop production.

Causes and Consequences

• Spatial information requires both location and description. GIS databases therefore commonly contain spatial data and attribute data linked through a common identifier. This allows a map feature to be connected with information such as its name, population or land-use type.

• Different geographical phenomena require different data structures. Raster data uses cells or pixels and is appropriate for continuous features such as elevation, temperature and satellite images. Vector data uses points, lines and polygons and is appropriate for discrete features such as schools, roads, rivers, districts and land parcels.

• GIS depends on an integrated system rather than software alone. Its five major components are hardware, software, data, methods or procedures, and people. The basic workflow is data collection, data input, data storage and management, data processing and analysis, and output or presentation.

• Spatial data must be positioned accurately. Coordinate systems provide the framework for identifying locations, while georeferencing ensures that maps, images and datasets align with one another. Latitude is measured north or south of the Equator, and longitude east or west of the Prime Meridian.

• Spatial measurements can be derived from mapped information. Distance on a map can be calculated using:

ground distance = map distance multiplied by the scale denominator when the scale is expressed as a representative fraction. Density can be calculated as: density = total quantity divided by area Slope gradient can be calculated as: slope gradient = vertical difference divided by horizontal distance and is often expressed as a percentage by multiplying by 100.

• Layer-based analysis enables comparison and combination. Overlay Analysis combines two or more map layers to identify relationships or suitable locations. Buffer Analysis creates zones around features, such as a protective zone around a river or a service area around a hospital.

• GIS supports direct geographical queries. It can identify all villages within a certain distance of a road or all areas with a particular soil type. This helps reveal where problems occur, who or what is affected, and which locations are most suitable for action.

• Remote Sensing and GPS extend the capabilities of GIS. Remote Sensing provides information about the Earth’s surface without direct physical contact, while GPS supplies accurate location, elevation, direction and time. Combining GIS, Remote Sensing and GPS provides a more complete understanding of places than using any one technology alone.

• Spatial technologies produce varied forms of evidence. Common GIS outputs include printed maps, digital maps, tables, graphs, images and three-dimensional visualisations. Thematic maps can show patterns such as rainfall, literacy or crop production, while a Digital Elevation Model represents surface height or elevation.

• Data quality determines the reliability of conclusions. Important concerns include accuracy, completeness, consistency, resolution, coordinate-system compatibility and timely updating. Reliable results therefore depend on accurate, current and properly georeferenced data, as well as suitable methods of analysis.

• Spatial analysis supports practical decision-making. Spatial information technology is useful in urban planning, transport management, agriculture, public health, emergency response, environmental conservation and infrastructure development. It supports planning, resource management, disaster studies, environmental monitoring and regional development.

What Gets Asked

• Compare Raster Data and Vector Data, including their structures and the types of geographical features for which each is most suitable.
• Explain how GIS, Remote Sensing and GPS work together and why their combination provides a more complete understanding of places than using one technology alone.
• Describe the five major components of GIS and explain the sequence of the basic GIS workflow.
• Explain how Overlay Analysis and Buffer Analysis support planning, including examples involving roads, rivers, hospitals and soil types.
• Apply and interpret the equations for ground distance, density and slope gradient, and explain the roles of latitude, longitude, the Equator and the Prime Meridian.
• Evaluate why accuracy, completeness, consistency, resolution, coordinate-system compatibility and timely updating are essential for reliable spatial analysis.