Lecture 8- 2.14.docx - Map distortion o All maps contain errors because of transformation process from the ellipsoidal surface to a flat map Tearing

# Lecture 8- 2.14.docx - Map distortion o All maps contain...

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Map distortionoAll maps contain errors because of transformation process from the ellipsoidal surface toa flat mapTearing- shapeShearing- angleCompression- areaoFor mapping small earth areas (large-scale mapping), distortion is not significantoFor mapping large areas, we cannot preserve all the properties and have to make decisions to keep shape or area or angle by selecting a map projectionReview: Map projectionoNo map projection can preserve all the properties (angle, area, shape, distance) at once. Equivalence and Conformality are incompatible – you must give up one to get the otherEquivalence- equal area property assuring that the relative sizes of all map features are correct. It is possible to make equivalent mapsConformality- property that preserves the correct shapes of small areas. Maintains all angles at each pointAzimuthality- Referred to as “true direction.” Direction from a point is preservedEquidistance- property that the scale of the map is correct, so distances are measured correctlyDetermining Deformation: two methodsoThe First Method:Use a geometrical figure (square, triangle) and plot it at several locations on the projection graticule. This method is effective, and its weakness is the lack of a