Techniques for drawing geodetic polygons

A non-transitory computer-readable medium storing instructions for drawing a geodetic polygon on a map, the instructions, when executed by one or more computing devices, cause the one or more computing devices to perform a method comprising:

• maintaining data that represents a geodetic polygon;
• wherein the data comprises an ordered set of geographic coordinates representing adjacent vertices along a perimeter of the geodetic polygon;
• transforming the set of geographic coordinates into a set of planar coordinates representing vertices of a planar polygon;
• wherein transforming the set of geographic coordinates into the set of planar coordinates includes proceeding through the set of geographic coordinates in a manner that represents a counter clockwise or clockwise traversal along the perimeter of the geodetic polygon until each geographic coordinate of the set of geographic coordinates is transformed to a corresponding planar coordinate;
• wherein proceeding through the set of geographic coordinates includes:
• transforming a first geographic coordinate of the set of geographic coordinates corresponding to a first vertex of the geodetic polygon to a first planar coordinate,
• transforming a second geographic coordinate of the set of geographic coordinates corresponding to a second vertex of the geodetic polygon to a second planar coordinate,
• wherein the first vertex and the second vertex are adjacent vertices according to the order of the set of geographic coordinates,
• calculating a distance along a horizontal axis of a two-dimensional plane between the first planar coordinate and the second planar coordinate, and
• determining that the geodetic polygon straddles a splitting meridian by determining that said distance is greater than one-half a horizontal extent of the map along the horizontal axis of the two-dimensional plane;
• where the geodetic polygon straddles the splitting meridian:
• dividing the planar polygon into a plurality of sub-figures;
• shifting at least one sub-figure of the plurality of sub-figures along the horizontal axis of the two-dimensional plane to produce a shifted sub-figure;
• and
• causing the shifted sub-figure to be displayed on the map concurrently with at least one other sub-figure of the plurality of sub-figures that was not shifted.

A geodetic polygon drawing computer system comprising:

• memory configured to store data that represents a geodetic polygon;
• wherein the data comprises an set of geographic coordinates representing adjacent vertices along a perimeter of the geodetic polygon;
• transformation logic coupled to the memory and configured to transform a state of the memory by transforming the set of geographic coordinates into a set of planar coordinates representing vertices of a planar polygon;
• wherein the transformation logic includes logic configured to transform a state of the memory by:
• proceeding through the set of geographic coordinates in a manner that represents a counter clockwise or clockwise traversal along the perimeter of the geodetic polygon until each geographic coordinate of the set of geographic coordinates is transformed to a corresponding planar coordinate,
• transforming a first geographic coordinate of the set of geographic coordinates corresponding to a first vertex of the geodetic polygon to a first planar coordinate,
• transforming a second geographic coordinate of the set of geographic coordinates corresponding to a second vertex of the geodetic polygon to a second planar coordinate,
• wherein the first vertex and the second vertex are adjacent vertices according to the order of the set of geographic coordinates,
• calculating a distance along a horizontal axis of a two-dimensional plane between the first planar coordinate and the second planar coordinate, and
• determining that the geodetic polygon straddles a splitting meridian by determining that said distance is greater than one-half a horizontal extent of a map along the horizontal axis of the two-dimensional plane;
• planar polygon splitting logic coupled to the transformation logic and configured to further transform the state of the memory by dividing the planar polygon into a plurality of sub-figures where the geodetic polygon straddles the splitting meridian;
• shifting logic coupled to the planar polygon splitting logic and configured to further transform the state of the memory by shifting at least one sub-figure of the plurality of sub-figures along the horizontal axis of the two-dimensional plane to produce a shifted sub-figure where the geodetic polygon straddles the splitting meridian;
• and
• display driving logic configured to cause displaying, on a computer display unit, the shifted sub-figure on the map concurrently with at least one other sub-figure of the plurality of sub-figures that was not shifted where the geodetic polygon straddles the splitting meridian.