Well positioned and styled labels shouldn’t need halos, but this isn’t always possible. When you have a lot of labels to add and you’re putting them over raster data you can’t use automatic detection of features between layers. Manually moving each label can be out of the question if you have thousands, so what do you do? The answer is add to add a halo, allowing the text to become legible even if it is overlying something the same colour.
However, adding a pure black or white halo to your text isn’t always a good look, even if it does make the text legible. Also in many cases might not even be needed as there is enough contrast with the background. Continue reading “Advanced Label Halos in QGIS 3.x”
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
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.
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.
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).
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”
These maps display the density and distribution of a phenomena over a geographic area. The markers, usually a dot or cross, represent the occurrence or an aggregation of occurrences which are then randomly distributed across distinct regions of the map. Colours can be used to represent different classifications to add an extra dimension to the map.
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 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”