GIS Glossary

A map layer representing a specific type of spatial data, such as land use, elevation, or population density. Thematic layers are fundamental for visualizing and analysing particular geographic phenomena.

The study and representation of the earth’s surface features, such as mountains, valleys, rivers, and craters. Topography provides the foundational context for terrain analysis and modelling.

The spatial relationships between connecting or adjacent features (such as connectivity, adjacency, and containment), crucial for ensuring data integrity in spatial analysis (inferred from standard GIS usage).

Constraints used in GIS to maintain correct spatial relationships between features, such as preventing overlapping polygons or ensuring lines connect at nodes(inferred from standard GIS usage).

The mathematical process of converting spatial data from one coordinate system or projection to another, ensuring spatial alignment and comparability (inferred from standard GIS usage).

Also known as drones, UAVs are remotely operated or autonomous aircraft equipped with sensors and cameras to capture high-resolution imagery and collect geospatial data for mapping, monitoring, and surveying.

A U.S. government agency responsible for studying and mapping the landscape, natural resources, and natural hazards of the United States. USGS data is foundational for many GIS analyses.

A global map projection system that divides the world into a series of zones, each with its own transverse Mercator projection. UTM is widely used for accurate spatial referencing and analysis.

In remote sensing, refers to the portion of the electromagnetic spectrum with wavelengths shorter than visible light; some sensors capture ultraviolet data for specialized analyses.

The degree of confidence or lack of precision associated with geospatial data or analysis results. Uncertainty can arise from data quality, measurement errors, or model assumptions, and is important to consider in all spatial analyses.

In vector data, an error where a digitized line does not extend far enough to meet another line at a node, affecting network connectivity and spatial analysis.

The use of GIS to support the technical and political processes of developing and designing land uses, infrastructure, and the built environment in urban and regional contexts. GIS aids in sustainable growth, resource allocation, and livability assessments.

A table associated with raster datasets that stores attribute information for each unique cell value, including the value itself and a count of cells with that value. VATs are essential for classifying and analysing raster data.

A digital vector data format developed by the U.S. Defence Mapping Agency for distributing vector datasets, especially for military and large-scale mapping applications.

A relational model-based vector data format similar to VPF, used for storing and distributing geographic vector data.

A fundamental GIS data structure that represents geographic features as discrete points, lines (polylines), and polygons, each defined by coordinates and associated attributes. Vector data is ideal for mapping boundaries, networks, and discrete features.

An individual coordinate (x, y) that defines the shape of a point, line, or polygon in vector data. Multiple vertices connected in sequence form lines and polygons.

In GIS, a logical or virtual table that provides a specific perspective or subset of data from one or more tables without duplicating the data itself. Views are used for efficient data access and analysis.

Another term for a view; a table whose data is not physically stored but is generated dynamically from existing tables when queried.

An OGC standard that allows users to access and manipulate vector spatial features over the web, supporting dynamic querying and editing of spatial data (standard GIS usage).