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I'm trying to generate evenly-spaced points (1m spacing) along a line shapefile in QGIS 3.4.3. This works with certain shapefiles. However, with other shapefiles, the units automatically change from "meter" to "degrees" and yellow triangles appear (see image below).

Does anyone know why this happens, and how I can make it work?

enter image description here

  • This is actually an excellent new feature (new to QGIS 3). QGIS tools have always used the units of the layer CRS, but it wasn't always obvious to the user. QGIS now makes it crystal clear what units will be used, and gives a warning when those units are degrees. – csk Jan 17 at 20:28
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Thats not a bug. Thats the unit of the CRS (Coordinate Reference System) the shapefile is in.

To use meters as distance your shapefile needs to be in a metric projection. There are lots of different ones available. For example UTM (Universal Transverse Mercator).

To reproject your shapefile to a metric projection do the following:

  1. Right click your layer, select export, select save features as...

enter image description here

  1. Now search for a fitting CRS. QGIS3 provides a preview on the location, where the selected CRS is commonly used. If +units=m appears in the description, the selected CRS is metric. (Take a look at https://epsg.io. I prefer this site to lookup CRS properties) When you choose a fitting CRS save the shapefile as a new file.

enter image description here

  1. Now use this new file for points along line tool.

Additionally I would like to provide some general links about projections/CoordinateReferenceSystems:

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    And just to add to this - the reason QGIS doesn't do this reprojection automatically for you is because there's often multiple, equally valid choices of projection. You need to make an informed decision of the correct local projection for your needs. – ndawson Jan 17 at 22:22

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