Map Projection Coordinate Systems Arc Viewmodule6 May 13

Outline n Map Projection n Coordinate Systems n Setting a Map Projection in Arc.

Map Projection n Transforming three-dimensional space onto a two-dimensional map Curved Earth surface Flat

Map Projection Types n Projections can be conceptually created by projecting from one geometric

Map Projection Cylindrical Projection Good for displaying the world

Map Projection Conic Projection Good for displaying mid-latitude area such as U. S.

Map Projection Planar Projection Good for displaying hemisphere with one focus

Map Projection Point or Line of Tangency n n Point or line of zero

Map Projection Point or Line of Tangency n Cylindrical/Conic projections have n n n

Coordinate Systems n Defined based on a variety of geodetic datums, map projections, units,

Coordinate Systems Datum n n n Used as a reference as in surveying or

Coordinate Systems Spherical vs Planar Spherical Planar Dimension 3 2 Projection yes no Latitude

Coordinate Systems Global vs Local Global feature example Local Used globally Specific to local

Setting a Map Projection in Arc. View Choosing a Map Projection depends on n

Setting a Map Projection in Arc. View Properties menu n In Arc. View. a

Manipulating a Map Scale in Arc. View Term definition n Map units are the

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Map Projection & Coordinate Systems Arc. View_module_6 May 13, 1: 30 PM

Outline n Map Projection n Coordinate Systems n Setting a Map Projection in Arc. View n Manipulating a Map Scale in Arc. View

Map Projection n Transforming three-dimensional space onto a two-dimensional map Curved Earth surface Flat Map

Map Projection Types n Projections can be conceptually created by projecting from one geometric shape (a sphere) onto another (a cone, cylinder, or plane) n n n Cylindrical: projects a sphere onto a cylinder Conic: projects a sphere onto a cone Planar: projects a sphere onto a plane.

Map Projection Cylindrical Projection Good for displaying the world

Map Projection Conic Projection Good for displaying mid-latitude area such as U. S.

Map Projection Planar Projection Good for displaying hemisphere with one focus

Map Projection Point or Line of Tangency n n Point or line of zero distortion Projection distortion increases with distance from the point of contact Point for planar projection Line for conic/cylindrical projection

Map Projection Point or Line of Tangency n Cylindrical/Conic projections have n n n Standard parallel (line of tangency) Central meridian Planar projections have n n Reference latitude (point of tangency) Central meridian

Coordinate Systems n Defined based on a variety of geodetic datums, map projections, units, and reference systems

Coordinate Systems Datum n n n Used as a reference as in surveying or mapping Based on the Spheroid (earth model) Usually referred to as a keyword (e. g. NAD 83, WGS 84)

Coordinate Systems Datum

Coordinate Systems Spherical vs Planar Spherical Planar Dimension 3 2 Projection yes no Latitude Longitude

Coordinate Systems Global vs Local Global feature example Local Used globally Specific to local area Geographic State Plane UTM National Grid

Setting a Map Projection in Arc. View Choosing a Map Projection depends on n n Which region to display (e. g. world, north pole, equator, US) Resolution of the region Geometric properties of the region Purpose of using maps such that the distortion can be minimized

Setting a Map Projection in Arc. View Properties menu n In Arc. View. a view's map projection can only be set if the map units of the spatial data it contains are decimal degrees

Manipulating a Map Scale in Arc. View Term definition n Map units are the units which the spatial data is stored in Map scale is the relationship between the dimensions of a map and the dimensions of the Earth Distance units are the units used by Arc. View to report the result of operations (e. g. measurement (measure tool), dimension of shape (draw tool), dimension of selection box (select feature tool))