I want to draw several squares of 250 by 250 meters in the North Sea using QGIS 2.14. I need the coordinates of each corner as ETRS89 coordinates.

I created a new scratch layer with CRS EPSG:4258, ETRS89, then click "Toggle editing" and "Add Feature" with the Advanced Digitizing Panel open.

I click on a point on the map and press "d" to enter the distance. I enter 250 and press Enter. I then can click the angle.

After I finish editing, the 250 meter square looks small. When I measure it using the measuring tool it measures as 156 meters. Why is this, and how can I work with meters?

Also, why does QGIS not display units in any of the input fields? I know it depends on the CRS, but how can I know what unit is used for which CRS?

  • 1
    Projected CRSs can preserve either area, angle or shape. I'm not familiar with the CRS you mentioned but it might be that it doesn't preserve distances and thus prevents you from adding accurate features
    – TobsenB
    Mar 24 '16 at 10:04

I would strongly suggest creating a grid of 250x250 m squares rather than doing it manually. You can do this from the toolbar:

Vector > Research Tools > Vector grid...

Vector grid

If you can locate the North Sea by a shapefile then you can use the extents of this layer; if you can locate by other means such as using a basemap from OpenLayers (or preferably QuickMapServices plugin) then you can use the extents of the canvas.

The output can be in polygons so you can select, edit, move the ones you want to keep and delete the remaining polygons. The amount of squares will depend on the coordinate extents you use.

Also, as @TobsenB mentioned, you may want to use a CRS which uses meters as distance.

  • Thanks for the answer, having a grid would be nice too, but the squares I am drawing are not on a grid, they are just several patches for possible sites that will be marked with buoys.
    – John
    Mar 24 '16 at 11:35
  • 1
    I only mentioned the grid as it's a fairly easy way to get squares. You can just copy a square from the grid layer and paste it multiple times onto another layer. You don't have to keep the grid =)
    – Joseph
    Mar 24 '16 at 11:43
  • I tried creating a grid with several different CRS settings, I do get a new layer, but it is never displayed. I feel like I need a different CRS, but which ones use meters? Where do you see this?
    – John
    Mar 24 '16 at 13:44
  • @John - When you select a CRS, there will be a description at the bottom. E.g. for EPSG:4258, it's: +proj=longlat +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +no_defs. Compare this to, for example, EPSG:27700: +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs. Here you can see +units=m is measured in meters. Some CRS have +units=ft which would be measured in feet etc. I'm not sure which would be best to use for the North Sea though...
    – Joseph
    Mar 24 '16 at 13:54

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