A disk of 2000 kilometers around a geo location:

A sector of a disk centered at Paris:

The center location of the geo disk can be specified in several ways:

The default location is the local geo position:

The geo disk radius can be specified as a Quantity object, or directly in meters:

Plot a disk with default size around Madrid:

Bearings are given in degrees, clockwise with respect to true north:

Use different stylings for geo disks:

The Mercator projection is conformal because it preserves shapes, though not areas or distances:

Compare with the default equirectangular projection:

Plot sectors to find overlap:

Plot various distances from the epicenter of the 1992 Landers earthquake:

A geo disk is the set of points whose distance to the center is at most its radius:

The boundary of a geo disk is a geo circle:

A GeoDisk object is described using coordinates and distances on the Earth, irrespective of the coordinates used in the final map. A Disk object is described using the coordinates of the final map:

It is possible to use a GeoPosition object to specify the center of the Disk object. Its radius, however, cannot be specified as a length on the surface of the Earth:

As we get closer to the poles, geo disks look more distorted in the equirectangular projection:

A geo disk containing a pole spans all values of longitude:

Progressive distortion of concentric geo disks of increasing radius:

Same disks (still concentric) in the Mercator projection:

The complement of a geo disk is approximately another geo disk centered in the antipodal location:

A large geo disk covers most of the Earth, including both poles. Only a small area is left uncovered:

All three sides of a geo disk sector are generically curved in most projections. The radii spanning from the center are geodesics:

Even starting from bearings and , the sides are curved:

A geo disk sector centered at a pole may be projected onto a rectangle:

Bearing at the South Pole coincides with longitude. Bearing α at the North Pole is related to longitude by the relation , taking both angles in degrees:

Large disks accumulating around the antipodal point, using a spherical model of the Earth:

The default reference model is an ellipsoid:

Interactively place a geo disk of fixed radius and observe how its form changes as a function of latitude:

Explore the arguments of GeoDisk:

Show that the cities in the US farthest from the US boundary are in Kansas. Take the US polygon:

Compute the distances in miles between consecutive points and accumulate them:

This is the total estimated length of the boundary, in miles:

Construct a parametrization of the boundary:

Draw 300 geo disks of 650 miles of radius along equidistant points of the boundary. There is a small space left uncovered—the region of the US farther than such distance from the boundary—and it is in Kansas: