Category Archives: GIS

Georeferencing in QGIS

QGIS is a great program and is a viable alternative to the old stalwart, ArcGIS. However, one aspect of ArcGIS that is vastly superior to QGIS is georeferencing maps. In ArcGIS, when you want to georeference a map, you simply load up the map, along with another pre-georeferenced image or map, click on the map you want to georeference, and then click on the place on the reference map that is equivalent. ArcGIS will then adjust the map you are georeferencing to account for the anchor point. This makes it a nice and easy workflow. If the map has known coordinates, you can right click and enter them.

QGIS offers a much more awkward way of georeferencing. The map you are georeferencing is placed in a separate window. Making an anchor point with an existing map can be awkward using the default settings, and as the version I am using (2.18.16), it is not possible to enter a geographic coordinate if you are using a projected coordinate system.

In addition to the above, there is not really a clear workflow tutorial on georeferencing in QGIS that I could find. I managed to make one up after some trial and error and finding information on places like Stack Overflow. I also had to tackle merging together scans of maps that were done in a piece-wise way. I am writing this so that I can look back to it in the future, but I also hope this proves useful to other people. Continue reading