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Practical work with QGIS (LOOM.02.331, A. AASA)

http://www.qgis.org/en/docs/training_manual/ http://maps.cga.harvard.edu/qgis/ Data for practical work: http://aasa.ut.ee/LOOM02331/data/data.7z

Exercise 1: Create thematic map “Distribution of Estonian population

in relation to nature preserves”.

Data layers: population_1km_grid_census2011.shp, preserves.shp Introduction to QGIS: http://mappingmashups.net/2012/11/30/a-very-short-introduction-to-qgis/ Output: map and short description.

Work steps:

Load data to QGIS (Add Vector Layer; *.shp!!)

Check the projection (for Estonian data projection is L-EST97; EPSG:3301)

Change the order of layers (topology)

Zoom full ; zoom to layer

Plugins (many analytical tools are available via plugins)

Change symbology (colours); double-click on layer name.

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Output (final map) is designed in “Print Composer” Save map as jpg / pdf / …

o Add new map to composer

o Legend: ; map scale:

o Export:

Exercise 2: How many people live in the 2 km buffer zone of Tallinn –

Tartu – Luhamaa highway? Data: Tallinn_tartu_luhamaa_road.shp, population_1km_grid_census2011.shp, Output: document with a thematic map and the population size in buffer zone. Work steps:

add relevant layers to your QGIS project

Create 2 km buffer for main_roads.shp. (How to create buffers:

http://wiki.osgeo.org/wiki/Buffer_with_QGIS )

Tutorial of performing spatial queries: http://qgis.spatialthoughts.com/2011/12/tutorial-performing-

spatial-queries-in.html

Create buffer:

Buffer attributes:

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Open “Spatial Query” https://www.qgis.org/en/docs/user_manual/plugins/plugins_spatial_query.html

Spatial query parameters and results

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After closing the results window save the results:

Open the “Statistics Panel” and choose the relevant layer and variable:

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What is the sum of population in 2 km buffer zone?

Create thematic map and export it as an image!

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Exercise 3: What is the population density (persons per km2) in

municipalities with borders intersecting the borders of natural

preserves? Compare it with the density of “other” municipalities!

Create thematic map! Data layers: population_in_municipalities_2011.shp, preserves.shp Work steps:

Load data to QGIS project (check Exercise 1)

Open attributes table:

Switch to the “Editing mode”

Open “Field Calculator”

Calculate area; expression: “$area / 1000000”, Save results.

Calculate population density (Create new variable [Fields and Values], calculate density

("pop_dens" / "area_km2")

Create spatial query to calculate densities (see Exercise 2)

Create thematic map and add two density numbers.