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Ground control

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Ground Control
ground control - [geodesy] A system of points with known positions, elevations, or both, used as fixed references in georeferencing map features, aerial photographs, or remotely sensed images.
[Category=Geospatial ] ...


Point
A point in two dimensions which is common to both an image and a topographic map, and can be represented by (X,Y) coordinates based on the map`s cartographic projection and grid system; ...

Ground Control Stations
Several ground control stations exist for the GPS. The Master Control facility is located at Schriever Air Force Base (formerly Falcon AFB) in Colorado.

: Point on the surface of the earth with known coordinates as represented by some geographic grid reference system.

7 Ground control points and OS maps
Of course, if the data are surveyed in from a GPS point, for example, and the co-ordinates are specified in full numeric form (e.g. 312300 445600 from the above example) the OS are not involved.

[edit]
The segment of GLONASS is entirely located within former Soviet Union territory.

Ground Control
Ground control refers to points on the surface of the earth with known coordinates as represented by some geographic grid reference system.

point(s)
GCRA
Geographic and Cartographic Research and Applications Section ...

Ground control point(s); Geodetic control point(s)
GCRA
Geographic and Cartographic Research and Applications Section ...

The points may be also (ir)regularly distributed and can be more than four points.
EXAMPLE
Most DXF/DWG drawings are done within XY coordinates. To transform them to a national grid, we can use 'v.

What is a Ground Control Point (GCP)?
Answer:
A precisely known UTM or Geographic coordinate of a point on the earth
used to geolocate the image. GCPs are needed to create absolute geolocated
DEMs.

Twenty three points (GCPs) digitized from 7.5 minute USGS topographic quadrangles (USGS quads) were used to rectify the October 5, 1990 SPOT-XS image to a Universal Transverse Mercator (UTM) map projection (RMSE = 0.29 pixels / 5.91 m).

Ground Control Point - GCP: Any point which is recognizable on both remotely sensed images, maps and aerial photographs and which can be accurately located on each of these.

Effective photogrammetry makes use of by which aerial photographs are carefully compared and registered to the locations and characteristics of features identified in ground-level surveys.

A system of transmitting satellites and ground control stations that allows someone with a suitable signal receiving and processing device (GPS receiver) to accurately determine their location at any point on or above the earth.

Acquire control points to produce about 35 orthoimages and determine the correspondence between the points and satellite image to produce correction models for Landsat 7 images using the source material provided (or made available) by ...

[aerial photography] An aerial photograph or photographs, referenced to a ground control system and overprinted with map symbology.
Reference map
[map design] A map designed to show where geographic features are in relation to each other.

To determine elevation of a place, it must be surveyed, in reference to a point.
Part of a topographic map of Haleakala (Hawaii), showing elevation.
[edit] Topography ...

raster image scanned from the diapositive or directly acquired from a digital sensor, 2) a digital elevation model with the same area of coverage as the digital orthophoto, 3) the image and ground coordinates of photo identifiable ground control ...

You can use the Traverse window to enter this into a line layer. It is important that you add this external boundary as accurately as possible, so start your traverse at an existing point or boundary that you believe to be accurate.

system to a known co-ordinate system on the basis of a set of selected points whose co-ordinates are known in both systems (given in the figure Overview of Coordinate Transformations as direct transformations). These points may be ground control ...

Or, to link map coordinates to points.Survey monumentAn object, such as a metal disk, permanently mounted in the landscape to denote a survey station.Universal Transverse Mercator (UTM)Universal Transverse Mercator.

Supplemental control points are those needed to relate the aerial photographs used for mapping with the system of ground control.

See also: See also: Map, Information, Location, Image, Control Point

GIS  Grid Reference  Ground Control Point

 
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