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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.
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
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