Alex McPhee Profile picture
🏜️ pronghorn/cartographer 🗺️ grain elevator enthusiast 🍁 maps and design, @CanadianPolling and @338Canada 🤠 25/m

Jul 18, 2022, 10 tweets

No cartographer can resist the infamous joy plot. Let me give away my secrets for doing it in #QGIS...

The basics: acquire a DEM from any source, make a point grid, use clipping functions to get the shape you want.

Sample raster values and translate points to get your squiggles...

Use points to path and you're done. Or are you?

If you're anything like me, this annoys you. A lot. There must be a better way.

The immensely powerful QGIS "geometry generator" functionality saves the day again. Let's just draw an opaque trapezoid underneath each line.

close_line(
line_merge(
collect_geometries(
make_line(start_point($geometry), translate(start_point($geometry),-1,-1)),
$geometry,
make_line(end_point($geometry), translate(end_point($geometry),1,-1))
)
)
)

One last thing - you have to enable "Control feature rendering order"...

Good to go! Now you can take R off your computer 🥴

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