http://www.uff.br/mapprojections/mp_en.html Throughout the globe this scale is constant. 6.2.3 Orthographic Projection (-Jg -JG) The orthographic azimuthal projection is a perspective projection from infinite distance. Preservation of angles makes conformal map projections suitable for navigation charts, weather maps, topographic mapping, and large scale surveying. A highly refined map designed by Renaissance polymath Albrecht Dürer and executed by Johannes Stabius appeared in 1515.[2]. The two axes of the ellipse indicate the directions along which the scale is maximal and minimal at that point on the map. But distortion in some form or the other is inevitable. The shapes and areas are distorted, particularly near the edges. Let’s look at the azimuthal projection in more detail. The meridians are vertical and equally spaced; the parallels of latitude are horizontal straight lines parallel to the equator with their spacing increasing toward the poles. Compass Basics http://www.giss.nasa.gov/tools/gprojector/ Some examples are Albers Equal-Area Conic, Cylindrical Equal Area, Sinusoidal Equal Area, and Lambert Azimuthal Equal Area projections. Orthographic Map Distortion. In orthographic projections, the point of perspective is at infinite distance on the opposite direction from the point of tangency. Those light rays intercept the globe onto a plane at various angles. In transverse aspect of planar projections, the plane is oriented perpendicular to the equatorial plane. The equations for the orthographic projection onto the (x, y) tangent plane reduce to the following:[1]. Like the stereographic projection and gnomonic projection, orthographic projection is a perspective (or azimuthal) projection, in which the sphere is projected onto a tangent plane or secant plane. Equivalent or Equal Area Projections
A map areaof a given size, a circle three inches in diameter for instance, represents same amount of Earth space no matter where on the globe the map area is located. They are written in terms of longitude (λ) and latitude (φ) on the sphere. The point of perspective for the orthographic projection is at infinite distance. The orthographic projection distorts shape and area near edges due to perspective. The point of perspective for the orthographic projection is at infinite distance. A map projection is the transformation of Earths curved surface (or a portion of) onto a two-dimensional flat surface by means of mathematical equations. Stereographic Projection ... Two standard parallels so as to minimize the map's overall scale distortion. Therefore shapes are represented accurately and without distortion for small areas. In normal aspect of cylindrical projection, the secant or standard lines are along two parallels of latitude equally spaced from equator, and are called standard parallels. Some of these properties are: 1. Scale factors of less than or greater than one are indicative of scale distortion. Lambert cylindrical equal-area projection, "Ellipsoidal Orthographic Projection via ECEF and Topocentric (ENU)", Map projection of the tri-axial ellipsoid, https://en.wikipedia.org/w/index.php?title=Orthographic_map_projection&oldid=1000390055, Wikipedia articles needing clarification from November 2014, Creative Commons Attribution-ShareAlike License, This page was last edited on 14 January 2021, at 22:14. This indicates that any line joining north and south poles (meridian) is true to scale and therefore distances are accurate along these lines. Features appear smaller between secant lines (scale < 1) and appear larger outside these lines (scale > 1). These are lines of equidistance. 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