Street Atlas (or Battleship) grids in QGIS 2.18

ICES rectangle map

Another guest blog from Liam Mason, based on his lightning talk at the 8th Scottish QGIS user group. You can follow Liam on Twitter via @marinemaps


D5. Miss.

A2. Hit. You’ve sunk my battleship! 🙁

If you’ve used a street atlas or played the boardgame Battleship, you’ll be familar with grid systems using letters for the horizontal (x) coordinate and numbers for vertical (y) coordinate.

Whilst these grids don’t have the resolution of a coordinate system like latitude/longitude or eastings/northings, they allow readers to quickly identify where a street is located on an atlas, or a ship on a boardgame.

Battleship boardgame
Battleship is now geohipster, embracing the hexgrid

Creating these type of grids in QGIS takes advantage of the grid options in composer, the @gridnumber attribute, and a wee bit of maths. Continue reading “Street Atlas (or Battleship) grids in QGIS 2.18”

3D mapping and bathymetry styling with QGIS 2.18

This is a guest blog from Liam Mason, a spatial analyst with Marine Scotland.  Some of his other data visualisations can be seen on his @marinemaps Twitter account or the Marine Scotland Maps portal maps.marine.gov.scot


[Edit: the tutorial was modified to use the GDAL-based DEM (Terrain Analysis) tools instead of Raster Terrain Analysis]

I love mapping bathymetric data in 3D. It’s almost magical, the ability to draw back the veil of the sea and reveal the mysterious landscapes below.

Yet, it’s remarkably simple to do using QGIS 2.8 or higher.

3D bathymetry map of inner Firth of Forth.
Bathymetry of inner Forth made using QGIS 2.8 and qgis2threejs

Continue reading “3D mapping and bathymetry styling with QGIS 2.18”

Creating Cartograms using QGIS 2.18

Cartograms

First a confession, I don’t like cartograms, at least not the kind where complex boundaries are warped sometimes beyond recognition. However they do have their place and where there aren’t the extremes in the data a cartogram can be a great data visualisation. It is outliers or extreme values that cause the maps to be distorted beyond usable recognition, and therefore look bad (see below).

Cartogram PaullHennig2016WorldMap.OAha.CC-BY-4.0
By John Paull and Benjamin Hennig (http://orgprints.org/30187/) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
Anyway, if your data isn’t going to produce a map like this then you can use the Cartogram plugin in QGIS. This allows you to quickly turn your map into one that removes the misrepresentation of small areas hiding large values. Continue reading “Creating Cartograms using QGIS 2.18”

Creating 3D choropleth or prism map in QGIS 2.18

Contains OS data © Crown copyright and database right (2017)

It is possible to very quickly render any choropleth map you make in QGIS in 3D using the Qgis2threejs plugin. Essentially the plugin allows you to turn a numerical attribute as a “height” for your data. The results from the plugin are outputted as an html page which can be easily shared in a folder or placed on the web for people to view. Continue reading “Creating 3D choropleth or prism map in QGIS 2.18”

Creating a Proportional Symbol map in QGIS 2.18

Creating proportional symbol maps in QGIS is made very easy in QGIS with two main methods for making them. You can use basic Single Symbol style with the  Size Assistant in the Data Defined Override,  or you can use the Graduated style and choose Size as the method of gradation. Below is a set of instructions on how to use either method to create proportional point symbols for your map. Continue reading “Creating a Proportional Symbol map in QGIS 2.18”