Cmpt 767 Visualization
Steven Bergner
November 5th, 2018
Overview
- Geographic information systems
- Typical GIS tasks
- GIS tools
Definition
- GIS
- desktop system to construct maps for display and analysis
- using layers of different types (raster and vector format)
- Geospatial
- any application involving geolocation data, not restricted to map display
Map projections
- See illustrations by K. Jordahl
- lon,lat -> x,y
- Names: unprojected coordinates, Plate Carrée
- Grid cells are perfect quares
- distorted shapes, sizes not proportional, area not preserved
- Mercator projection, also cylindrical projection
- increases area the farther away from the equator you are
- directions are locally true
- shape is perserved locally, conformal
- Lambert projection, on cone rather than cylinder
- two lines of longitude are chosen for true scale
- Area preserving projection
- True projection shape: ellipsoid
GIS Tasks
- Maps
- Handle raster and vector data formats
- Data integration from multiple sources
- Application domains
- Geospatial analysis
- Display maps on the web
- Integrate with geospatial DBs
- GIS desktop apps
- Techniques
- Map projections (lon,lat) –> (x,y)
- Layer types, composition
- Geometry operations, creation, validation
Census tracts
Geographic areas located in Canada’s largest census metropolitan areas of
more than 100,000 people
Boundary files
- Definition of lat/lon region boudaries
- Get 2016 Census tract data from Stats Canada in ArcGIS .shp format
First Steps in QGIS
- ‘Add Vector Layer’ from top icon on in left toolbar, open .shp file
- ‘Open Attribute Table’ in context menu of layer name
- CTUID is UID for census tract within metropolitan area
- ‘Add delimited text layer’ (comma icon) to load .csv file
- Choose ‘No geometry’ (attribute only)