lineoverlapping-featuresprint-composerqgissymbology
I want to make a map, with two plots. I want to draw them only with a line along the perimeter of each one, with different colour. My problem is that when the lines overlap, only one colour is showed.
This is my problem:
Then I want to draw each on with different colour, I would like something like that (without the thin black line):
But I get this result:
Is there are any way to draw the lines inside the perimeter using QGIS?
This question is a well known cartographic problem, and there are several ways to implement:
1) Offset.
Like the underground/tube maps of cities, lines running o same set of tracks appear next to one another, like these example in NYC.
This is only applicable if you have a limited number of overlapping lines.
2) Color-based.
Changing the color of the feature based on density/intensity/overlap of features, like this example of underwater cables.
3) Symbol-based.
as @recurvata suggested, you can change the symbol of overlapping lines by changing the thickness based on number of overlapped lines. Though line thickness in this map corresponds to volume, it can also be used for sum of overlap.
There isn't a definite answer to the best practice here, it all depends on your needs and message the maps you produce purvey.
You can use a Label placement defined by Geoemtry Generator. Use it to define a polygon where placements are allowed: inside a buffer around the outer boundary of your polygons (bufferA), but not inside a buffer around a polygon from another layer, the "label blocking" polygon. Let's call the buffer around this "label blocking" polygon bufferB. Now you have to clip (difference) from bufferA the area of bufferB.
To achieve this, use this expression for label placement, where polygon2 is the name of the layer containing the label blocking polygons and the buffer size of 8000 and 1000 can be changed to suit your needs:
difference (
single_sided_buffer (boundary($geometry), -8000),
collect_geometries (
overlay_nearest (
'polygon2',
buffer ($geometry, 1000),
limit:=10
)))
Screenshot: yellow polygons are labeled in a way to avoid labels where the red polygon from another layer overlaps. The blue polygon is just for visualization purpose and shows the geomtry cretated using Geometry generator with the above expression: it defines the areas where labels are allowed:
Best Answer
Set your border to simple line and check Only draw the line inside the polygone (or something like that)