Alaska grid

Description

This projection was developed to provide a conformal map of Alaska with less scale distortion than other conformal projections. A set of mathematical formulas defines a conformal transformation between two surfaces (Snyder 1993).

Projection method

Modified planar. This is a sixth-order equation modification of an oblique stereographic conformal projection on the Clarke 1866 spheroid. The origin is at 64° N, 152° W.

Point of tangency

Conceptual point of tangency at 64° N, 152° W

Linear graticules

None

Properties

Shape

Perfectly conformal

Area

Varies approximately 1.2 percent over Alaska

Direction

Local angles are correct everywhere.

Distance

The minimum scale factor is 0.997 at approximately 62°30' N, 156° W. Scale increases outward from this point. Most of Alaska and the Aleutian Islands, excluding the panhandle, are bounded by a line of true scale. The scale factor ranges from 0.997 to 1.003 for Alaska, which is one-fourth the range for a corresponding conic projection (Snyder 1987).

Limitations

Distortion becomes severe away from Alaska.

Uses and applications

• Conformal mapping of Alaska as a complete state on the Clarke 1866 spheroid or NAD27
• Not optimized for use with other datums and spheroids

Parameters

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