Page tree
Skip to end of metadata
Go to start of metadata
TermDescription

Absolute Accuracy

How closely a map feature location matches its real-world counterpart. Nearmap: better than 75cm RMSE.

Aerial Photography

Aerial photography is any photography taken from the air. Typically, aerial photographs are taken with specialized, high-quality, large format cameras that point down vertically from the aircraft to the ground below. Orthophotography is derived from overlapping vertical aerial photography.

Application Programming Interface (API) 

An interface definition that permits invoking services from application programs without knowing details of their internal implementation.

ArcGIS A popular GIS tool from Esri.  It is used for creating and using maps, compiling geographic data, analyzing mapped information, sharing and discovering geographic information, using maps and geographic information in a range of applications, and managing geographic information in a database. 
ArcReaderAllows to view and query maps created with the other ArcGIS products. 
AutoCAD Commercial computer-aided design (CAD) and drafting software application. Developed and marketed by Autodesk. Our imagery can be inserted into AutoCAD without scale. 
AutoCAD Map 3D Commercial CAD software with extensions that support mapping projections and functions. PhotoMaps can be inserted through WMS. 
Autodesk Software for the architecture, engineering, construction, manufacturing, media, and entertainment industries. 
Computer Aided Design (CAD) Computer-aided design and drafting. CAD systems are used to create maps and plans and are closely related to GIS systems. Although most CAD systems lack certain features essential to GIS analysis, such as the power to manage different spatial coordinate systems and database capabilities, many CAD systems have been developed into full GIS with the addition of necessary functions.
DatumA model of the earth that is used in mapping. The datum consists of a series of numbers that define the shape and size of the ellipsoid and it's orientation in space. A datum is chosen to give the best possible fit to the true shape of the Earth.
Digital Elevation Model (DEM) Elevation data representing the Earth’s surface. Typically, this is represented as a gridded height value and commonly stored in ASCII and GeoTIFF formats.
Digital Orthoimagery (DOI) 

Digital Orthoimagery is a remotely-sensed digital picture, stored in a raster data format. It is a geo-referenced image prepared from a vertical photograph or other remotely-sensed data in which displacement of objects due to sensor orientation and terrain relief have been removed.

Digital Surface Model (DSM) A DEM that follows the tops of buildings and vegetation. 
Digital Terrain Model (DTM) Digital Terrain Model is a sample of DEM used to model a land surface. This is usually needed for applications such as water shed management and contour mapping. We do not currently offer a DTM version of our data. 
Elevation The height above sea level of a point on the Earth’s surface. 
Esri Environmental Systems Research Institute is an international supplier of geographic information system (GIS) software, web GIS and geodatabase management applications with commonly used software packages ArcGIS. 
GDA94 Geocentric datum of Australia 94; the coordinate system used by Australian governments and many organizations; originally defined to be close to WGS84 in 1994, but slowly diverging due to tectonic motion.
Geographic Information System (GIS) A system that allows decision-making using geographic data, typically via spatial visualization. 
Geographic Registration The spatial referencing of an orthoimage to an area on the earth's surface. An image must be geographically registered in order to use it in a GIS as an overlay. 
Georeferencing Associating data or an image with a location; the content of a map is intrinsically georeferenced. 
Global Positioning System (GPS) 

A system of satellites, computers, and receivers that can determine the latitude and longitude of a receiver on Earth by calculating the time difference for signals from different satellites to reach the receiver.

Ground Control Point Points of accurately known geographic location used to register imagery and other coverage data to ground position. 
Ground Sample Distance (GSD) 

The area on the ground represented by each pixel in a digital orthoimage. The smaller the pixel, the more detail visible in the image. The distance on the ground between camera samples (pixels) during PhotoMap capture; indicates the level of detail.

Keyhole Markup Language (KML)An XML notation for representing geographic data within Internet-based, two-dimensional maps and three-dimensional Earth browsers.
Latitude The North-South position of a point on the Earth’s surface. 
Lidar Laser-based analogue of radar, used to capture a DEM. 
Longitude The East-West position of a point on the Earth’s surface. 
MapBrowserNearmap’s web-based imagery browser. 
MapInfoA popular GIS tool from Pitney Bowes.
Metadata Information about the content, quality, condition, and other characteristics of data. 
Nadir The direction pointing directly below a particular location; that is, the vertical direction towards the earth at a specified location, orthogonal to a horizontal flat surface there.
North American Datum 1983 (NAD83) A common spatial reference system used in US and Canada to better model local mapping applications. Default system used in State Plane projections. 
Oblique Photographs taken at an angle providing view perspective and depth.  Typically, a look of angle of 10 degrees or more is considered oblique but most often 45 degrees is the preferred angle. Unlike orthorectified imagery which is corrected to map space, oblique images are single photos appearing as captured in the aircraft (image space). 
Open Geospatial Consortium (OGC) An international organization formed to defined various geospatial standards related to data formats and interfaces. Of particular interest, OGC defined the WMS/WMTS interfaces standards. 
Ortho Vertical photographs are often used to create orthophotos, which have been geometrically "corrected" so as to be usable as a map. In other words, an orthophoto is a simulation of a photograph taken from an infinite distance, looking straight down to nadir. Perspective must obviously be removed, but variations in terrain should also be corrected for. Multiple geometric transformations are applied to the image, depending on the perspective and terrain corrections required on a particular part of the image. See also Vertical.
Orthorectification The removal of perspective distortion in photos due to camera tilt and terrain; a crucial step when producing accurate imagery. 
Pixel   Two-dimensional picture element that is the smallest non-divisible element of a digital image. 
Projection The systematic transformation of points on a globe into points on a planer map Nearmap: MapBrowser uses the Web Mercator projection. 
QGIS A popular free GIS tool.
Resolution The resolvable detail in an aerial image, may correspond to the GSD, but may be lower due to blur. 
Root Mean Square Error (RMSE) Root mean square error, a statistical measure of measurement accuracy. 
Satellite Imagery Images of Earth collected by imaging satellites operated by governments and businesses around the world. Satellite imaging companies sell images by licensing them to governments and businesses such as Apple Maps and Google Maps. 
Scale The ratio of distances on a map to those same distances on the earth's surface. Ground resolution relates to mapping scale. For example, a map scale of 1 inch on the map = 200 feet on the ground is equivalent to an image ground resolution of 6 inches (pixel size). A scale of 1-to-400 is equivalent to 1-foot resolution. A scale of 1-to-100 is equivalent to 3- inch ground resolution. 
State Plane A coordinate system (grid) of plane rectangular (x, y) coordinates for pre-determined zones in each of the 50 states. 
Terrain The three-dimensional shape of the Earth’s surface.  
TilingImages are subdivided into smaller units to reduce the physical file size and the amount of computer processing required. Tiles usually cover a regular rectangular grid. 
Tile Map Service (TMS) A defacto-standard web protocol for serving georeferenced map tiles can be used to integrate PhotoMaps into third-party applications. 
Vertical Vertical photographs are often used to create orthophotos, which have been geometrically "corrected" so as to be usable as a map. In other words, an orthophoto is a simulation of a photograph taken from an infinite distance, looking straight down to nadir. Perspective must obviously be removed, but variations in terrain should also be corrected for. Multiple geometric transformations are applied to the image, depending on the perspective and terrain corrections required on a particular part of the image. See also Ortho.
Web Map Service (WMS) An OGC open standard web protocol for serving georeferenced map image can be used to integrate PhotoMaps into GIS tools. A server generates a map image for each client request. 
Web Map Tile Service (WMTS) An OGC open standard web protocol for serving georeferenced map image can be used to integrate PhotoMaps into GIS tools. A server sends predefined map tile images for each client request. 
Web Mercator A version of the Mercator projection, popularized by Google maps. 
WGS84 World Geodetic System 84; a standard coordinate system for the Earth and regularly realigned to account for tectonic motion. 
  • No labels