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(a) Cylindrical projection (b) Conical projection (c) Zenithal projection (d) Conventional projection.
Radius of the globe = Given R.F. actual radius of the earth.
1. Reduced earth : The model of the earth is represented by the help of a reduced scale on a flat sheet of paper. On this model the network of graticule can be transferred.
2. Parallels of Latitude : These are the circles round the globe parallel to the equator and maintaining uniform distance from the poles. They are demarcated as 0° to 90° North and South.
3. Meridians of Longitude : Longitudes are also the elements of map projection. These are drawn north to south direction from one pole to the other and two opposite meridians make a complete circle i.e. circumference of the globe.
4. Global Property : These are :
(i) distance between any given points of a region;
(ii) shape of the region;
(iii) size or area of the region in accuracy;
(iv) direction of any one point of the region bearing to another point.
1. Correctness of the area
2. Direction
3. Distance
4. Shape of the area.
Map : Map is drawn on the sheet of paper. The meridians and parallels intersects straight or curved lines. Maps are drawn to show the physical and cultural features of area.
(i) Source of light
(ii) Developable surface
(iii) Global properties.
(i) Shape of landmasses, waterbodies or political units.
(ii) Distance between places.
(iii) Areas of landmasses, waterbodies or political units.
(iv) Directions of any given place in relation to any other place.
(v) Locations of places or areas in relation to the entire earth.
Explain the differences between Parallels and Meridians.
Parallels: The north or south angular distance of a place from the equator is called latitude. Lines drawn an east-west parallel to the equator are called latitudes. There is 90° latitude north of the equator and 90° latitude south of the equator. These distance of 90° latitude is points only called north pole and south pole.
The network of Parallels and Meridians
The links joining north pole and south pole are called meridians of longitude. The meridian passing through Greenwich is known as Prime Meridian. There are 180 meridians towards the east and west of the prime meridian. Thus, there are 360 meridians in all.
Map Projection : A map projection is a means of representing the lines of latitude and longitude of the globe on a flat sheet of paper.
Non-developable Surface : A non-developable surface is that which cannot be cut of any folded into flat sheet paper, e.g. globe.
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Non-developable Surface : A non-developable surface is that which cannot be cut or folded into flat sheet paper, e.g. globe.
Orthographic Projection : On these projection the correct shap of the are of a country is shown.
Oblique Projection : These projects are known as conical projection. In these projection in inner surface of the cone touches some parallel known as stanarderd parallel.
Meridians of Longitude : The meridians of longitude refer to the angular distance, in degrees, minutes and seconds of a point east or west of the Prime (Greenwich) Meridian. Lines of longitude are often referred to as meridians.
1. Source of light : It includes perspective and non-perspective projections and mathematical projections. Perspective projections can be drawn by projecting the image of the network of the meridians and parallels of a globe on developable surface.
2. Developable surface : These are classified as conical-cylindrical and zenithal projections.
3. Global properties : The projections are also classified on the basis of global criteria they satisfy. The criteria include equal area, projections, correct shape projections and azimuthal projections.
Characteristics of conical projection with one standard parallel :
1. The parallel scale correct only along the standard parallel. It is exaggerated as to proceed to north and south of it.
2. The meridian scale is correct everywhere.
3. The pole is represented by an arc.
4. The meridians and parallels cut each other at right angle.
5. As the distortion of shape occurs both north and south of the standard parallels, the projection neither equal area of orthomorphic.
6. It is suitable to the area which covers more than 20° of latitude.
7. It is fairly accurate for narrow latitudinal zone lying in temperate latitudes.
Characteristics of Mercator’s Projection
1. All parallels of latitude are projected equal in the length to the equator of the reduced earth.
2. The parallel scale along the equator is always true, but away from it, it is exaggerated towards north and south. Hence the polar regions are not shown in this projection.
3. The meridians are placed evenly, so that their spacing is true to scale on the equator.
4. Since, the exaggeration of the scale along the parallels is accompanied by equal exaggeration of the scale along the meridians areas become grossly exaggerated in high latitudes. For this very reason, polar regions are not shown in this projection.
5. The projection is orthomorphic as each meridian intersects the parallel at right angles and the scale ratio remains constant throughout.
6. Although the area of a small square is enlarged considerably but the shape is preserved in this projection.
7. Since, it shows the correct directions, it is always valuable to the navigators and pilots.
Properties :
1. Parallels and meridians are straight lines. They intersect at right angles.
2. The distance between meridians remains equal whereas distance of parallels go on increasing towards the pole.
3. All parallels are of the same length.
4. The scale along the equator is correct as the length of equator is equal to the length.
5. The meridians are longer than the meridians on the globe.
6. The shape of country is represented truly at every point as parallels and meridians intersect each other.
7. The projection is orthomorphic.
Limitations :
1. The scale along the poles and meridians increases rapidly towards the poles.
2. Poles in this projection cannot be shown.
2. The meridians are straight lines. The meridians intersect the parallels at right angles.
3. Distance at meridians are fairly accurate.
4. The distance between two parallels on this projection is true.
5. There is a convergence of merdians towards the poles and closer to each other towards the poles.
6. This projection is neither equal area nor orthomorphic.
7. The standard parallel is truly divided.
Limitations :
1. It is not used for world map due the extreme distortion.
2. The distortions along the poles and near the equator makes the projection disadvantageous for representating very large areas.
Uses :
1. It is most suited for mapping middle latitude areas.
2. A long narrow strip of land running along the standard parallel in the east-west direction is shown fairly correctly.
1. Source of light : It includes perspective and non-perspective projections and mathematical projections. Perspective projections can be drawn by projecting the image of the network of the meridians and parallels of a globe on developable surface.
2. Developable surface : These are classified as conical-cylindrical and zenithal projections.
3. Global properties : The projections are also classified on the basis of global criteria they satisfy. The criteria include equal area, projections, correct shape projections and azimuthal projections.
Characteristics of conical projection with one standard parallel :
1. The parallel scale correct only along the standard parallel. It is exaggerated as to proceed to north and south of it.
2. The meridian scale is correct everywhere.
3. The pole is represented by an arc.
4. The meridians and parallels cut each other at right angle.
5. As the distortion of shape occurs both north and south of the standard parallels, the projection neither equal area of orthomorphic.
6. It is suitable to the area which covers more than 20° of latitude.
7. It is fairly accurate for narrow latitudinal zone lying in temperate latitudes.
Characteristics of Mercator’s Projection
1. All parallels of latitude are projected equal in the length to the equator of the reduced earth.
2. The parallel scale along the equator is always true, but away from it, it is exaggerated towards north and south. Hence the polar regions are not shown in this projection.
3. The meridians are placed evenly, so that their spacing is true to scale on the equator.
4. Since, the exaggeration of the scale along the parallels is accompanied by equal exaggeration of the scale along the meridians areas become grossly exaggerated in high latitudes. For this very reason, polar regions are not shown in this projection.
5. The projection is orthomorphic as each meridian intersects the parallel at right angles and the scale ratio remains constant throughout.
6. Although the area of a small square is enlarged considerably but the shape is preserved in this projection.
7. Since, it shows the correct directions, it is always valuable to the navigators and pilots.
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