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Bipolar oblique conformal conic

  • Description
  • Projection method
  • Lines of contact
  • Linear graticules
  • Properties
  • Limitations
  • Uses and applications
  • Parameters

Description

This projection was developed specifically for mapping North and South America. It maintains conformality. It is based on the Lambert conformal conic, using two oblique conic projections side by side.

Learn more about the Lambert conformal conic projection

Projection method

Two oblique cones are joined with the poles 104° apart. A great circle arc 104° long begins at 20° S and 110° W, cuts through Central America, and terminates at 45° N and approximately 19°59'36" W. The scale of the map is then increased by approximately 3.5 percent. The origin of the coordinates is 17°15' N, 73°02' W (Snyder 1993).

Lines of contact

The two oblique cones are each conceptually secant. These standard lines do not follow any single parallel or meridian.

Linear graticules

Only from each transformed pole to the nearest actual pole

Properties

Shape

Conformality is maintained except for a slight discrepancy at the juncture of the two conic projections.

Area

Minimal distortion near the standard lines, increasing with distance

Direction

Local directions are accurate because of conformality.

Distance

True along standard lines.

Limitations

The bipolar oblique conformal conic projection will display North America and South America only. If having problems, check all feature types (particularly annotation and tics) and remove any features that are beyond the range of the projection.

Uses and applications

  • Developed in 1941 by the American Geographical Society as a low-error single map of North and South America
  • Conformal mapping of North and South America as a contiguous unit
  • Used by USGS for geologic mapping of North America until it was replaced in 1979 by the transverse Mercator projection

Learn more about the transverse Mercator projection

Parameters

Supported in ArcInfo Workstation only. Projection-specific parameters are set by the software.

Related Topics

  • List of supported map projections
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