Geospatial and GIS Glossary

A Digital Elevation Model (DEM) is a raster-based digital representation of Earth's surface elevation, widely used in GIS, remote sensing, terrain analysis, and surface modeling.

USGS Digital Line Graphs (DLG) are digital cartographic datasets containing roads, waterways, contours, and land boundaries in a standardized exchange format.

Digital Orthophoto Quadrangle (DOQ): A geometrically corrected aerial image with map accuracy, combining photo detail and precise positioning for GIS and mapping.

USGS provides Digital Orthophoto Quarter Quadrangles (DOQQs) for easier use and storage. Four DOQQs combine to form one full DOQ quadrangle.

Digital Raster Graphic: Scanned 1:24,000 USGS topographic map. Ideal as a backdrop for manual distance measurement and coordinate lookup; not spatially editable.

A Digital Surface Model (DSM) represents Earth's surface, including terrain, buildings, vegetation, and structures, for urban planning, aviation, telecom, and environmental analysis.

A Digital Terrain Model (DTM) represents the Earth's bare surface elevation, excluding buildings and vegetation, for terrain, hydrology, and flood analysis.

DXF: A vector file format (ASCII or binary) for CAD data exchange, enabling AutoCAD interoperability and conversion to GIS coverages.

Data Conversion: Converting geographic data into compatible formats (e.g., DLG, TIGER, DXF, DEM) so data from multiple sources can be integrated and analyzed in GIS.

A data dictionary defines database fields, formats, and values. In GIS/GPS projects, it standardizes geographic features and attributes for consistent, accurate data collection.

A data type specifies the type of values a column or variable can hold, such as text, integers (whole numbers), or floating-point (decimal) values.

A database is a structured collection of related data that enables efficient storage, organization, retrieval, management, and updating of information.

A datum is a reference framework that defines Earth's shape and position, enabling accurate coordinates, mapping, surveying, and GIS. Examples: WGS84 and NAD83.

Digitizing converts map features into digital X,Y coordinates by tracing points, lines, and polygons manually or through automated scanning technology.

Dissolve merges adjacent polygons with the same attribute by removing shared boundaries, creating one unified feature.

Drone Façade Inspection uses UAVs to safely inspect building exteriors, capturing high-resolution images to detect defects, damage, and maintenance needs.

UAV-based LiDAR uses drones to capture high-resolution, accurate 3D terrain and surface data in difficult, inaccessible, or hazardous areas.

Drone mapping uses UAVs to capture high-resolution aerial images and spatial data, creating accurate maps, orthomosaics, and detailed 3D models.

Drone surveying uses UAVs with high-res cameras, LiDAR, thermal, and multispectral sensors to capture precise spatial data for maps, orthophotos and 3D models.

Drone inspection uses UAVs to safely examine structures and equipment, capturing high-resolution images and data to detect defects and monitor conditions safe