I'm tasked with displaying reserve data on a map but also displaying the category data for each site even though they overlap with other reserves. E.g. I have a category, "Birdwatching" which applies to 50 sites whilst the category, "Grassland" applies to 30 sites but overlaps with the birdwatching category thus a site could have "birdwatching and grasslands".

I created a layer for every category, so a user could select "birdwatching" and view the 50 of 100 reserves that meet this rule. But how do I go about composing a map that includes all ten categories?

  • Take a look at the options for "fill style" for your layer symbology. You can either choose some kind of point or line-based fill, or adjust transparency levels so that other layers will show through. – JoshC Mar 17 '18 at 14:07

The OP suggests that the sites across the 10 layers are the same and a single site can be a grassland and a bird watching site at the same time.

The solution to this is not to create a layer for every category but rather have one layer and create a column for every category and fill it with 1 if the site belongs to this category and 0 if not. Then you could represent the sites using the rule-based styling.


Based on an additional comment by the OP, a good option to represent the attributes of the sites is to use Layer Diagram Options in QGIS (Second button on the label toolbar). Using a rule-based symbology with 10 attributes can potentially create lots of classes.

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You have the option to represent the data as:

  • A pie chart

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  • Text diagram

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  • Histogram

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The tool settings are rather straightforward to use.

  • This is something I also considered (data is already displayed yes/no) but i'm confounded by how to compose a map that displays this information as that is part of my instructions. I understand how a GIS interface could answer the question, E.g. User selects the categories they are interested in then it shows relevant sites but I don't know how show that on a single or multiple maps for the sake of a report. Is it possible to have a symbol segmented based on the number of categories for that site? – McGraw Mar 18 '18 at 9:09
  • This seems like a solution but QGIS crashes each time I select the categories. I reduced it two categories and it created the pie chart but it was not filled in for any of the sites. – McGraw Mar 19 '18 at 9:35
  • Did you add the attributes to the assigned attributes? – Techie_Gus Mar 19 '18 at 10:00
  • I completed the following: Selected layer>diagram options>pie chart>selected the 10 attributes from available attributes>clicked green cross to place them into assigned attributes>clicked ok> layer appears with circle over each node but no segments>qgis crashes. – McGraw Mar 19 '18 at 11:28
  • 1
    Can't argue with that. – McGraw Mar 19 '18 at 11:50

You need to use rule based styling to use more then one category. There are many online tips guides and tutorials on rule based styling in qgis.

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