DGN - a CAD file format supported by MicroStation (Bentley Systems) and Interactive Graphics Design System (Intergraph), for displaying buildings, highways, bridges and other large projects.
Digital Surface Model (DSM) - a topographic elevation model of the Earth surface that provides a geometrically highly accurate representation for the purpose of overlaying the model with a wide range of GIS data. DSM provides a surface elevation of every natural and artificial feature visible within the image area. DSM forms the basis for creating true orthophoto production and 3D models.
Digital Elevation Model (DEM) - an extraction of the DSM with all elevations not representing ground surface (bare earth) removed. DEM data is used to create a terrain surface, terrain ortho-rectification and contour depiction.
Digital Terrain Model (DTM) - a topographic model of the Earth surface. The DTM is created using the DEM and the addition of "break lines" or higher density points that define adequately all natural and artificial changes in surface slopes. A DTM enables the generation of contours to reflect actual terrain surfaces and to render computerized 3D terrain visualization techniques.
DWG - a file naming extension created for AutoDESK for use in AutoCAD software. The DWG format stores two and three-dimensional design data along with metadata.
ECW - an Enhanced Compressed Wavelet file. These files use the ECW extension. The format is designed to optimize aerial imagery through the efficient compression of data without loss of image contrast. A ECW file can be used by most popular GIS products such as ArcView.
ESRI Shapefile - the native file format for ArcView and other ESRI software products. SHP files are digital vector in format and describe geographic references in the form of points, polylines and polygons with assigned attributes.
GeoTIFF - based on the Tagged Image Format File (TIFF) standard and includes extra header tags to embed geo-referencing information within the file. These files use the TIF extension. The file format embeds information such as projections, co-ordinate systems, ellipsoids, datum’s and other necessary information to establish the image's exact spatial reference.
Geographic Information System (GIS) - a collection of computer hardware, software, and geographic data for capturing, storing, manipulating, analyzing, and displaying all forms of geographically referenced information.
Inertial Measurement Unit (IMU) - detects altitude, location and motion such a pitch, roll and yaw when an airplane is in flight. Using a combination of accelerometers and gyroscopes, an airplane can track position with a high degree of accuracy.
MrSID - stands for Multi-resolution Seamless Image Database file. These files use the .SID extension. The format is designed to compress massive raster images while maintaining image quality. A .SID file format integrates with popular GIS software from ESRI, Intergraph, MapInfo, Autodesk and others.
Orthophoto - a photographic map. Conventional aerial photography images cannot be used to accurately measure distances because the images do not account for the effect of the camera position and attitude, camera lens distortion, image scale variations and displacement caused by topography. An orthophoto is orthorectified to create a uniform scale so that it is possible to use it for accurate measurement and overlay GIS data to create a comprehensive image database.
Photogrammetry - the science of taking stereoscopic aerial images and using geometry, mathematics and physics, to enable accurate measurements of the earth's surface.
Raster graphics - digital images captured photographically. A common term for raster images is bitmaps because the image is actually bits mapped to a display grid. Raster graphics are difficult to modify without information loss so they do not scale well and breakup when enlarged. Raster graphics can have extensions like .BMP or .JPG.
Vector graphics - digital images that have mathematical constructs associated with the shapes and representation within the images. The art or image is created and saved as a sequence of vector statements, each representing a quantity and direction. Vector graphics, unlike raster, do not contain bits, but instead have a series of points to be connected. Vector graphics can have extensions like SHP or DWG