QGIS

How to create custom geometries based on vector shapes to use on the map legend or symbology on QGIS

This week, I am showing you how to create custom geometries to enhance your legends on QGIS Print Layout. Specifically, how to create these geometries based on vector files that you already have. The example I will provide is how to create the Legend Patch Shape for the state of Rio Grande do Sul, in Brazil.

A draggable Truesize Leaflet map of the Brazilian states, and how to do the same for your own country or region

The good news is that using Leaflet Truesize plugin, you can add your own customized draggable polygons to the map. A map that I thought almost immediately is the representation of the draggable Brazilian states, so you could compare them to each other and to the size of other countries. And that is why this is used as an example for this tutorial.

How to generate a Leaflet.js webmap on QGIS with qgis2web plugin, and how to adjust some fundamental features on the map directly on html and JavaScript

Leaflet maps can definitely be generated from scratch. Many people and companies do that. But, because I am a QGIS enthusiast and many of my maps are already on QGIS projects, I can get the best of both worlds. I generate my basic map using as many specifications available on qgis2web as possible, and then, edit the html and the JavaScript generated by the plugin to adjust the map to my needs.

Workaround for: qgis2web freezes while changing map type

So far, so good, but then you try to change the type of map between the available options (currently, OpenLayers, Leaflet and Mapbox GL JS) QGIS freezes and you have to close the application via Windows Task Manager. I observed the occurrence on QGIS 3.20 Odense and on QGIS 3.16 Hannover, version of qgis2web 3.16.

Testing some of my favorite changes in QGIS 3.20 Odense

Today QGIS 3.20 “Odense” was released! In today’s post, I will test some of my favorite features of the new version. To check all the new features and the bugs fixed, check the full Changelog of QGIS 3.20.

Using SAGA Raster Calculator on QGIS - a quick tutorial

The SAGA Raster calculator is useful because it allows to make some calculations that the regular QGIS Raster Calculator does not. Especially, it allows us to use the X and Y coordinates of the raster as inputs for our calculations. How do we start?

When I mosaic two rasters, the size of the resulting raster is almost always larger than the sum of the sizes of the original rasters. Why is that?

Short answer: your GIS software needs to fill the blanks in the area with NoData pixels. Long answer: I will demonstrate what happens by an example on QGIS 3.18, and show why the final raster tends to be larger than the other two summed.

How to georeference images using QGIS 3

Today, I am going to show you how to georeference an image using QGIS 3.18. Maybe you found this image in a paper, or maybe it is an aerial photograph. It doesn’t matter! If you know the coordinates of at least two non collinear points, you can add geolocation to the image!

How and when to use QGIS 3 tools “Warp (reproject)”, “Clip raster by extent” and “Clip raster by mask layer”

Today, I am discussing different ways of cutting (clipping) a raster in QGIS and what they do. Especially, I am comparing QGIS GDAL tools “Clip raster by mask layer”, “Clip raster by extent” and “Warp (reproject)” in what are they used for, and what exactly do they do to the original raster data.

A simple tutorial for generating a South Pole Azimuthal map on QGIS

Azimuthal maps are certainly more common in the northern hemisphere, but they can be done for the southern hemisphere as well. They can be useful for localizing places in Antarctica, South America, Africa, and Oceania. These maps can be included in scientific publications or presentations. Last week I presented my research in the EGU General Assembly 2021 and part of the location map was prepared in South Pole azimuthal projection. These steps are the basics of how to make an azimuthal map for South Pole.