GeoVisibleRegionBoundary

GeoVisibleRegionBoundary[{lat,lon,h}]

is a one-dimensional GeoGraphics primitive that represents the boundary of the region on the surface of the Earth visible from the point of coordinates lat,lon and height h above the reference ellipsoid.

GeoVisibleRegionBoundary[pos]

represents the boundary of the region visible from the position pos.

Details

  • GeoVisibleRegionBoundary assumes an ellipsoidal shape for the Earth and does not take into account the terrain elevation. Corrections for atmospheric refraction are not included.
  • The angles lat,lon in GeoVisibleRegionBoundary[{lat,lon,h}] can be given as numeric objects in degrees, DMS strings, or as Quantity angles.
  • The height h in GeoVisibleRegionBoundary[{lat,lon,h}] can be given as a numeric amount of meters or as a Quantity length.

Examples

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Basic Examples  (3)

The visible region from an altitude of 10 km over the reference ellipsoid:

The visible region from geostationary orbit:

The region currently viewable from the International Space Station:

Scope  (3)

Visible region boundary from a {lat,lon,h} position:

Smaller heights correspond to smaller visible regions:

For vanishing height, the visible region collapses to a point and default padding is used:

Specify the coordinates as Quantity objects:

Specify latitude and longitude as DMS strings:

Specify the viewing position as any type of geodetic position:

Move vertically 1 kilometer from New York, assuming the city is on the reference ellipsoid:

Applications  (1)

Show the region boundary currently viewable from the International Space Station together with its orbital track:

Properties & Relations  (3)

GeoVisibleRegionBoundary corresponds to the boundary of a GeoVisibleRegion primitive:

Position and height of Willis Tower:

Show the region visible from the top of the building, assuming flat local terrain:

Horizon distance from elevation d, assuming a spherical Earth of radius :

Evaluate the formula for the height of Willis Tower:

Compare a GeoDisk of that radius with the result of GeoVisibleRegionBoundary:

Zoom around the east border of the geo disk:

Interactive Examples  (1)

Take an ellipsoid of semiaxes {a,b} and a point at distance r from its center and geocentric latitude α. Then the boundary of the visible region is parametrized as follows:

The viewing point is denoted in red and the visible region boundary in blue. It is a plane curve, orthogonal to the vector colored in blue:

Neat Examples  (1)

Define a list of various notable (tall) North American structures:

Form a list of properties for each building:

Show the visible region, assuming flat local terrain:

Introduced in 2014
 (10.0)