CRDDS Method of the Month

GIS: Introduction


Phil White

Earth, Environment & Geospatial Librarian

outpw.github.io/gis_mini1

In-Depth Workshops:


  1. Oct 13: GIS in Python with GeoPandas
  2. Oct 27: QGIS
  3. Nov 10: ArcGIS

Tuesdays 12:00 to 2:00 pm

Nov 13: GIS Day

Outline


  1. What is "GIS"?
  2. What is "Geospatial Data"?
  3. Core Concepts
  4. Common Techniques

Do you have a favorite mapping or GIS project?

Drop it in the chat!

What is GIS?

We're surrounded by GIS

GIS:

(Geographic Information System) An integrated collection of computer software and data used to view and manage information about geographic places, analyze spatial relationships, and model spatial processes.

John Snow & Cholera: The classic GIS example

John Snow & Cholera:

  • John Snow: physician, anesthesiologist, founder of modern epidemiology
  • London cholera outbreak of 1854
  • Analyzed patterns of the outbreak to locate epicenter
  • Discovered well at epicenter; removed well handle, outbreak stops

But not just any old data...

Geospatial Data!

5 Things:

  1. Points
  2. Lines
  3. Polygons
  4. Pixels/Cells
  5. And their associated attributes

Vector Data

Raster Data

Vector Data
Raster Data
And their attributes... Cells have values, aka attributes

Digital Elevation Model
(DEM)


  • White Cell = 2402.89m

  • Black Cell = 1735.06m

More on data in 2 weeks!

Finding GIS Data Sept 22

But... putting stuff on a map is more compicated than it seems...

2 Things:

  1. Datums

  2. Projections

Because Earth's shape is irregular and changing, assigning locations is imperfect.


We use imaginary reference systems to approximate.


We tend to call this a "datum."

You might consider the datum to be the "grid",
like latitude and longitude.

Projection, or how we warp the grid

Projection


  • All projections have a purpose
  • Always a compromise
  • Shape, area, distance, direction
  • Can't have them all!

    • Mercator Projection

    Good for direction

    Bad for shape/size

    (Hello Greenland!)

    Gall-Peters Projection

    Learn more about mapping stuff in 3 weeks!

    Map Design Sept 29

    What can I do with GIS?

    Take some data...


    Do some stuff...


    Communicate new info!

    Stuff we do:

    Symbolize


    Aggregate


    Measure


    Overlay


    Interpolate


    Geocode

    Georeference

    Symbolization

    mapschool.io
    Wikimedia
    demographics.virginia.edu/DotMap/
    Overlay
    Jordan Wirfs-Brock
    Georeference
    David Rumsey Center
    Geocode

    How do I do all this fun GIS stuff?

    Tools for GIS

    Learn more about GIS tools and software next week!

    Tools for GIS Sept 15

    Thank you

    Upcoming:

    Contact: