Map Projection Parameters Map Projection Parameters Standard Points

Map Projection Parameters

Map Projection Parameters • • • Standard Points and Lines Projection Aspect Central Meridian Latitude of Origin Light Source Location

Standard Points and Lines Definition: Points or lines of intersection between the developable surface and spheroid. Named Standard Lines: If standard line falls a line of latitude, it is known as a standard parallel. If standard line falls on a line of longitude, it is known as a standard meridian.

Standard Parallels

Why are Standard Points and Lines Important? Those corresponding places on the map will have no scale distortion. The father away from the standard point or line(s), the greater the distortion or deformation occurs. Secants can help minimize distortion over a large area by providing addition control.

Projection Aspect Definition: Position of the projected graticule relative to ordinary position of the geographic grid on Earth A developable surface with the axis running from north to south pole creates a normal aspect

Globe Normal Axis

Normal Aspect

Non-Normal Aspect

Central Meridian Definition: The meridian that defines the center of the projection. i. e. the meridian in the center of the map

Latitude of Origin Definition: The Latitude that defines the center of the projection. i. e. the latitude in the center of the map

Light Source Location Definition: The location of the hypothetical light source in reference to the globe being projected. Three Primary Positions…

Three Primary Positions of Light Sources Gnomonic Stereographic Orthographic