Wednesday morning : GIS exercise

QGIS Exercice

Step 1 : Install QGIS

Step 2 : Load some background layers from the ITB

  • The most interesting shapes are probably UN_VOL (buildings), EL_STR (streets), SUP_CAN (canals). But you can also have a look at the others.
  • Simply drag and drop the .shp file onto QGIS

Step 3 : Georeference the Ughi map

  • Open the georeferencer using the menu Raster>Georeference
  • In the new window, choose “open raster” open raster and select “ughi.jpg” in the “iconographic_cartographic_sources” folder.
  • Create some points using the “add point” button add point, each time choose a recognizable spot on the Ughi map, and choose a corresponding point “from the map canvas”
  • Once you have around 10 (or more) points, click on the play button play
  • On the window that pops up, choose an “output” destination somewhere on your drive (best is to put it alongside your QGIS project)
  • Click OK and wait a bit. Once finished, check if the georeferencing is acceptable (don’t expect it to be precise though). If not, add some points or check if you didn’t enter wrong points.

Step 4 : Create a new data layer

  • In the layer menu, choose new>shapefile layer
  • Set the type to polygon
  • Set the name of the layer to “buildings”
  • Add some attributes like name, type, const_year, and possibly some more
  • Click OK, and save it somewhere (best is to put it alongside your QGIS project)

Step 5 : Add some data

  • Select the layer your just created
  • Toggle on the “edit mode” toggle
  • Create some features using the “add features” button add features, and assign data.
  • Save the data every now and then by toggling off the “edit mode”.

Step 6 : Create an atlas

  • Use the menu project>new print composer
  • In this new window, add a new map from the map canvas add map
  • Select this item, and in the properties window, check “controlled by atlas”
  • In the atlas generation tab on the right, check “generate an atlas”
  • Choose your buildings layer as the coverage layer
  • Check “export single file if possible”
  • Add text using the add label button. Customize the text by selecting the text box and entering text in the properties tab.
  • Use some of the layer’s attributes as text, using the “insert an expression” button, and selecting some attributes from the “Fields and Values” category
  • To have a preview of the atlas, click the previewatlas and browse through the pages using the previous and next buttons Previous next
  • If everythink looks OK, choose export atlas as PDF from the atlas menu

Step 7 : Export to 3D map

  • Install the qgis2threejs plugin, using the plugin manager (plugins>Manage and install plugins)
  • Zoom in the area you’re interested in on the map
  • Run the plugin which is located in the web/qgis2threejs menu
  • X-in your “buildings” layer
  • Setup the settings so that it displays well (for instance : activate labels and choose the name field as label, if you have a height field, you can use it as the extrusion height as well)
  • Click run
  • You can always change the settings an click run again.

Documentation

QGIS provides good documentation for begginers.

You can get additionnal help from :

Tip : set your QGIS installation to English, it makes searching for help easier if you use the english terms

Links

 

 

Just in case, this is Olivier. Best, Yannick.

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