I'm trying to create a map with spot levels using an underlying 1m resolution DEM TIFF file. My thought process so far is to create a grid of points with a height value field over the area of interest (say 6m x 6m) and then select the highest in each cell. Then draw a 5 buffer around all these points. If any of these buffers contain more than 1 point keep the highest value and delete the rest. This should result in nicely spaced point that I can label neatly without overlaps or the chance of the label not being the highest.

I've tried making a template for this using the Graphical Modeller, but I'm not great with expressions (I have more of a survey/cartography background and its been a while since I did this at school!)

What is the best way to go about achieving this?

Images attached showing graphically what I'm trying to achieve.

Alternatively is there a way to use labels to give greater weight to points with a higher elevation field so that they are displayed instead of the lower values?

(source: redd.it)

6x6m grid cells

(source: redd.it)

Highest value in each cell

(source: redd.it)

5m radius from high point in each cell. Keep highest point in each circle buffer that contains >1 points

(source: redd.it)

remaining points for DEM elevation labelling

example of what I'm trying to achieve

  • 2
    Couldn't you resample the DEM to your desired size (say 6x6m) and only then convert to points to display the values?
    – JonasV
    Oct 23, 2020 at 13:21
  • I should have clarified that the position of the highest point is critical for the plan (shows minimum clearance to under water obstructions on nautical navigation plans). See example image here Example plan clip Oct 23, 2020 at 13:53
  • 1
    You can use gdalwarp with the resampling method set to max
    – JonasV
    Oct 23, 2020 at 14:01
  • I spent some time in the modeler and have something that works but the problem is that it's not practical until there is a way to append algorithm output to an existing layer (from what I understand it is an unsolved bug).
    – Gabriel
    Oct 23, 2020 at 20:18


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