Lecture 2 Cartographic Principles PDF

Introduction to GIS Cartographic Principles Dr Lawal Billa Introduction to Geographical Information Systems [email protected] School of Geography, University of Nottingham.MC Introduction to Geographic Information Systems School of Geography, Universi...

Introduction to GIS Cartographic Principles Dr Lawal Billa Introduction to Geographical Information Systems [email protected] School of Geography, University of Nottingham.MC Introduction to Geographic Information Systems School of Geography, University of Nottingham  Introduction to Geographic Information Systems Dr Nick Mount School of Geography, University of Nottingham [email protected]  Dr Nick Mount Introduction to Geographic Information Systems [email protected] School of Geography, University of Nottingham A cartographical map projection is a formal process which converts (mathematically and graphically) map features from a sphere or ellipsoid surface onto flat projection surface. Many projections have been designed, just a few are currently in widespread use. Some map projection designs are for special/specific purposes  Types of Map Projections  Azimuthal /planar Projections  Conic Projections  Cylindrical Projections  Equal-Area Projections (preserves correct area)  Conformal Projections (preserve correct shape over small area)  Planer/Azimuthal projection Conical projection Cylindrical projection Easiest case: Orthographic, planar projection. Constructed by tracing parallel rays from features on surface of globe onto flat sheet of paper. Introduction to Geographic Information Systems Dr Nick Mount School of Geography, University of Nottingham [email protected]  Orthographic Stereographic Different assumptions of position and arrangement of traced rays. Radial rays produce different projections to parallel ones. Introduction to Geographic Information Systems Dr Nick Mount School of Geography, University of Nottingham [email protected] 1. Earth is wrapped around by flat sheet made into cone. 2. Rays are traced onto paper and paper is unfolded. Introduction to Geographic Information Systems Dr Nick Mount School of Geography, University of Nottingham [email protected]  Dr Nick Mount Introduction to Geographic Information Systems [email protected] School of Geography, University of Nottingham  Reason for projection You definitely have to use one form of projection due the curvature of the earth. When surveying small areas (