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Tier 2 Training. Projection/ArcCatalog. We start off with Projection !. Projection in a few sentences. A map projection is a method of showing the 3-D planet Earth on a 2-D plane, (inevitably causing distortions). The distortion can occur in distance, area, shape, or direction.
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Tier 2 Training Projection/ArcCatalog
Projection in a few sentences • A map projection is a method of showing the 3-D planet Earth on a 2-D plane, (inevitably causing distortions). • The distortion can occur in distance, area, shape, or direction. • Each projection will result in different types and amounts of distortion.
Coordinate System • After projecting 3-D planet to a 2-D plane, it must have an X and Y coordinate to know where features are. • UTM and BC Albers has its own x and y coordinate system. • Longitude and Latitude does not need a projection to identify it’s feature location. iMapBC • iMap can show all 3 coordinates at the same time of the same location.
Which projection/coordinate system do you use ? • There are 3 common type you will be working on: • BC Albers • UTM • Geographic (Longitude, Latitude)
BC Albers No Zone? It’s the whole BC
Things to Remember • BC Albers is one set of coordinates with zero area distortion for any part of BC (only BC). • UTM are in different zones. If a GIS data is in UTM 10, and you change it to UTM 11, the data will therefore, fly off somewhere else. • Longitude and Latitude must be in decimals and not in degrees for ArcGIS to recognize the coordinates. Use a longitude to latitude, degree to decimal conversion website, e.g. • http://www.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html • The best choice, if possible, is the BC Albers projection.
ArcCatalog • Allows you to connect data to both ArcCatalog/ArcMap (Important) • These data can be in your network drive or external connection (LRDW) • Create GIS formats from scratch • View some GIS formats as one file, not many (ex. Shapefile) • GIS data management • Preview spatial data/tables with basic tools (zoom in, zoom out .etc) • Allows you to search/filter items inside your directory (Important) • Open and run Arctoolbox • Add extensions • Setup Metadata
ArcCatalog Object Filter Before After
Projection Data Paths BC Albers Projected Coordinate Systems/National Grids/Canada/NAD 1983 BC Environment Albers.prj UTM 10 Projected Coordinate Systems/Utm/Nad1983/NAD 1983 UTM Zone 10N.prj You will remember these paths soon enough!!!