Map projections and its types explanation and examples.pptx
- 2. • Map projections inherently distort one or more of the following: • Area-preserving projection – Also known as equal area or equivalent projection • Shape-preserving projection – Referred to as conformal or orthomorphic • Direction-preserving projection – Includes conformal, orthomorphic, and azimuthal projections (only from the central point) • Distance-preserving projection – Known as equidistant, which displays the accurate distance between one or two points and all other point
- 3. • MAP PROJECTION CATEGORIES
- 4. • The main categories of map projections are: • Cylindrical Projections: These projections are created by wrapping a cylinder around the Earth and projecting its features onto the cylindrical surface. Examples include the Mercator, Transverse Mercator, and Miller Cylindrical projections. • Conic Projections: In this category, a cone is placed over the Earth, and the features are projected onto the conical surface. Common conic projections are the Lambert Conformal Conic and Albers Equal-Area Conic projections. • Azimuthal Projections: Also known as planar or zenithal projections, these projections use a flat plane that touches the Earth at a single point. The Earth’s features are projected onto the plane. Examples of azimuthal projections include the Azimuthal Equidistant, Stereographic, and Orthographic projections. • Pseudocylindrical Projections: These projections resemble cylindrical projections but use curved lines instead of straight lines for meridians and parallels. Some popular pseudocylindrical projections are the Sinusoidal, Mollweide, and Goode Homolosine projections.
- 5. CONTENTS • INTRODUCTION • MAP SCALE • MAP PROJECTION • PROPERTIES OF MAP PROJECTION • CLASSIFICATION OF MAP PROJECTION • COMMONLY USED MAP PROJECTION • CONCLUSION • REFERENCES
- 6. INTRODUCTION • A map is a representation of all or part of the Earth drawn on a flat surface at a specific scale. • It is a visual representation of an area – a symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes. • It is a diagrammatic representation of the earth's surface or part of it, showing the geographical distributions, positions, etc. of natural or artificial features such as roads, towns, relief, etc. • Cartography is the study and practice of making maps and one who make maps is called a cartographer.
- 7. MAP SCALE • Map scale refers to the relationship (or ratio) between distance on a map and the corresponding distance on the ground. For example, on a 1:100 000 scale map, 1cm on the map equals 1km on the ground. • The map scale may be expressed in three ways and the pictorial representation of these three types is shown in the figure.
- 8. MAP PROJECTION • A map projection is a systematic transformation of the latitudes and longitudes of locations on the surface of a sphere or an ellipsoid into locations on a plane. • It is the representation of the objects and information on a curved surface in a plane using mathematical and geometric relations. • Transformation from the earth surface to a flat surface always involves distortion either in size, shape or in relative location and therefore no map projection is perfect.
- 9. 1. The term ‘projection’ comes from the notion of placing a light source inside transparent globe and projecting shadows of the meridians, parallels and other geographic features onto a sheet of paper placed tangent to the globe. 2. Position of light source can be- o Gnomonic i.e light source is at the centre. oStereographic- light source is at the antipode of the point of tangency. oOrthographic- light source is at an infinite distance from the point of tangency.
- 10. When transferring the image of the earth and its irregularities on the plane surface of the map, three factors involved, they are Geoid: Rendition of irregular spheroidal shape of the earth. An ellipsoid: Geoids are then transferred to a regular geometric reference surface Projection: Geographical relationship of the ellipsoid, still three dimensional form, are transformed into two dimensional plane of a map.
- 11. PROPERTIES OF MAP PROJECTION • Three principal cartographic criteria; 1. Conformality : correct representation of shapes. 2. Equidistance : correct representation of distances. 3. Equivalency : correct representation of areas.
- 12. CLASSIFICATIONS OF MAP PROJECTIONS • The map projection are classified according to five criteria : 1. Nature of the projection surface as defined by geometry 2. Coincidence or contact of the projection surface with the datum surface 3. Position or alignment of the projection surface with relation to the datum surface 4. Properties of cartographic requirements, and 5. Mode of generation of datum surface and coordinate systems.
- 13. • Three main types of map projection are: 1. Cylindrical projection. 2. Conic projection. 3. Azimuthal or planar projection.
- 18. • In cartography, a map projection is any of a broad set of transformations employed to represent the curved two-dimensional surface of a globe on a plane