Week 3 Mapping Day 2

pdf version

Digitization: day 2.

1. Download

  1. Download just a few more shapefiles from this link

  2. Assemble into 9 groups.

  3. Download one of the maps for the day:

2. Setup

  • Reload your QGIS setup.
  • With ‘on-the-fly’ reprojection enabled, change your default CRS for the projection to “Google Mercator”. (You can do this by typing “Google” into the search box;
  • Add the two new layers you downloaded in section 1 (‘streets’ and ‘buildings’).

3. Georectification

Georectify the map

  1. Enter georectification mode (under QGIS 2.14 “Essen”, raster menu -> georeferencer).
  2. Click the add raster button.
  3. Set points at street intersections by clicking the add points button.
  4. Choose a transformation type (use ‘polynomial 1’).
  5. Choose a name for your output file.
  6. Make sure the desired output is also in the Google Mercator projection.

Comparing to tabular data

Each group choose a page from this site. View as list. Group 1 should take file 1; etc.

Everybody in your group should trace the outline of a different house on your map.

  1. Menu "layer" -> "New Layer". This will be a polygon layer.
  2. Right-click or control click on the layer for “toggle editing.”
  3. Click the green object with the ‘add star.’.
  4. Draw around a polygon.
  5. We could add metadata around this point. We won’t, now, but something like this could form the kernel of someone’s final project…

Note on Sources

You may at some point want to work with a larger set of buildings, maps, or streets. Here are links to the original sources.