lineqgisstylesymbologywidth
I am acquiring data related to the hydrography of a territory. I would like to use a symbology that allows me to have a line whose thickness decreases as it reaches its end (like the example in the image).
I could divide each line into many segments and give each one its own thickness, but I'm looking for a much faster and more effective method. The geometry generator could probably be a solution .
Currently, I have vectorized each waterway with a single line.
Hope this one helps.
Use GDAL rasterize to conver polyline to raster, then it is possible to run r.neighbors with a 3 (by 3) sized neighbourhood. see also in this post.
This is my result on some lines drew on WGS84. This is only a snapshot but the method works for all featurs and/or raster cells. Original polyline colored yellow, in black are the polyline to raster result. Then layered underneeth in red is the last raster with a 3 pixel "buffer".
It quite similar to the workaround you have suggested, but enable you to drop scripting and use GRASS tool instead. I find it to be most intuitive way to handle such a problem.
I can't tell if "blob of color" means all the trails are now joined together, or that it takes a lot of screen area.
If the former, see if you have dissolve buffer results checked, as it will dissolve all the 8 ft wide polygons representing individual trails into one.
If the latter, it might be a symbology problem, where you have set the outline too thick, try thinning it, or changing the border of the polygons from millimeters to map units.
Best Answer
Try geometry generator: