Common QGIS CRS Problems and How to Fix Them

Introduction

One of the most important settings when you work with map data in QGIS is the coordinate reference system (CRS). If the CRS is set incorrectly, map data appears shifted, or layers do not land where you expect. In the figure below, the lake data from National Land Numerical Information is displayed on top of OpenStreetMap, but because the CRS is wrong, Lake Biwa appears in the sea.

This article explains common problems with CRS settings in QGIS and how to fix them, with concrete examples. For the basics of setting a CRS in QGIS and the steps involved, see the article below.

When a layer has no CRS information

If a layer has no CRS information, you must assign the correct CRS manually. Shapefiles store their CRS information in a .prj file, so when that file is missing, you have to set the appropriate CRS yourself.

This section uses the lake data from National Land Numerical Information to show how to set a CRS. Checking the contents of the downloaded data shows that there is no .prj file.

If you add a shapefile like this to QGIS and have selected Prompt for CRS in the setting for adding a layer with no CRS information to QGIS, the Specify CRS for layer XXX dialog opens for you to choose a CRS.

When this dialog appears, first check which CRS the layer was created in. The page where you downloaded the data usually lists the CRS, so choose the appropriate CRS based on that information.

On the lake data page, the CRS is listed as “JGD2000 / (B, L)”. This means the data was created in the latitude and longitude (B, L) CRS of the JGD2000 geodetic datum, and you choose the CRS in the dialog based on this information. “B, L” are the initials of the German words Breite (latitude) and Länge (longitude).

First, enter JGD2000 in the Filter box. The Predefined Coordinate Reference Systems list is filtered, so click Geographic (2D), which contains the latitude and longitude CRSs, select JGD2000 (EPSG:4612) in it, and then click OK.

First, enter JGD2000 in the Filter box, and the Predefined Coordinate Reference Systems list is filtered. The JGD2000 (EPSG:4612) you want to set here belongs to the Geographic (2D) group, which contains the latitude and longitude CRSs. Click Geographic (2D), select JGD2000 (EPSG:4612) in it, and then click OK.

Check the map canvas. The lake data now overlaps the basemap and appears in the correct position.

If you do not set the CRS correctly, the data appears shifted from its actual location. So when the CRS dialog appears, check which CRS the layer you are about to add was created in, and set the correct CRS.

A layer appears in an unintended location

If you choose an inappropriate CRS in the Specify CRS for layer XXX dialog, the layer can appear in an unintended location.

The figure below shows lake data from Japan, but because the CRS is set incorrectly (to Web Mercator), the lakes appear in the Gulf of Guinea, in central West Africa.

To reset the CRS, select the Source tab in the layer properties and click the Select CRS button (globe icon). A dialog for setting the CRS opens. Check the CRS of the data and set the correct one.

A question mark appears in the Layers panel

If you add a layer to QGIS without setting a CRS in the Specify CRS for layer XXX dialog, a “?” mark appears next to the layer in the Layers panel. Hover over the “?” mark to see the message “Layer has no coordinate reference system set!”.

In this case, follow the same steps as above and set the correct CRS from the Source tab of the layer properties.

The map looks distorted

For example, when you add the administrative area data from National Land Numerical Information to QGIS, the map shows the Japanese archipelago stretched horizontally. This happens because the project CRS is JGD2011, a latitude and longitude CRS.

To show the map in the familiar shape, change the project CRS to a projected CRS such as Web Mercator (EPSG:3857).

To change the project CRS, follow these steps.

1. Click EPSG:XXXX at the bottom right of the QGIS window.
2. The CRS settings dialog opens. To change to Web Mercator (EPSG:3857), enter 3857 in the Filter box.
3. In the Predefined Coordinate Reference Systems list, select Projected → Mercator → WGS 84 / Pseudo-Mercator (EPSG:3857), and click OK.

The CRS of the map changes, and so does its appearance.

Conclusion

This article introduced common problems with CRS settings in QGIS and how to fix them. Setting a CRS in QGIS may seem difficult at first, but once you understand the basic ideas and operations, you can prevent these problems before they happen.