Double Stereographic

Description

A conformal projection.

Projection method

Planar perspective projection, viewed from the point on the globe opposite the point of tangency. Points are transformed from the spheroid to a Gaussian sphere before being projected to the plane.

All meridians and parallels are shown as circular arcs or straight lines. Graticular intersections are 90°. In the equatorial aspect, the parallels curve in opposite directions on either side of the equator. In the oblique case, only the parallel with the opposite sign to the central latitude is a straight line; other parallels are concave toward the poles on either side of the straight parallel.

Point of contact

A single point anywhere on the globe.

Linear graticules

Polar aspect—all meridians.

Equatorial aspect—the central meridian and the equator.

Oblique aspect—the central meridian and parallel of latitude with the opposite sign of the central latitude.

Properties

Shape

Conformal. Local shapes are accurate.

Area

True scale at center with distortion increasing as you move away from the center.

Direction

Directions are accurate from the center. Local angles are accurate everywhere.

Distance

Scale increases with distance from the center.

Limitations

Normally limited to one hemisphere. Portions of the outer hemisphere may be shown, but with rapidly increasing distortion.

Uses and applications

Used for large-scale coordinate systems in New Brunswick and the Netherlands.

Parameters

Desktop

• False Easting
• False Northing
• Central Meridian
• Scale factor
• Latitude of origin