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I want to make a heat map of species biodiversity like the people did in the picture below. I can sort of get it to work by setting my layer with multiple polygon subclasses in the Layer styling panel to "Single" instead of "Graduated", and then modifying the opacity. However, this only allows me to use one color, and the areas with few species are really dim. I want to make a graduated color scheme of multiple colors. I have hundreds of species, so it isn't feasible to go and change the color of every single polygon layer. I also don't want to rasterize the polygons into a grid to make a series of grid squares. I want it to be in vectors

enter image description here

This is what my POLYGON layer looks like. It is not a series of points, it is a series of polygons. The example map I attached is made up of overlapping polygons too, not points. Though some spots may look like points in their map, they are actually circular polygons

enter image description here

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  • It is not too clear what you are asking so some clarification is most likely needed. Do you have the polygon layer with a numeric field with the "bio-diversity" number in it? If that is the case then you are looking to produce a thematic map. The above map looks like a "hotspot" map made from point samples. – AWGIS Mar 4 '20 at 19:27
  • Post updated. See second picture I've posted – MapDeath Mar 5 '20 at 2:12
  • It appears that you would want categorised symbols then which is what your legend seems to be showing there. Doesn't that give you the desired results? – AWGIS Mar 5 '20 at 8:24
  • No I want a graduated color scheme, notice how in the map as polygons are overlaid on top of each other, it is actually a color ramp. There aren't different categorized colors for each polygon, else it would all be a brown jumbled mess. You wouldn't be able to see yellow on red for example like you actually do in the figure – MapDeath Mar 12 '20 at 20:42
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I suppose you have a dataset of points.

To achieve described visualization you should use three tools from the Processing panel.

Step 1. Heatmap — this tool makes a raster layer from a vector point layer. It's a necessary step to resolve the problem.

Step 2. Contour tool to transform a raster layer to a vector line layer.

Step 3. Lines to Polygons tool to transform the vector line layer to the vector polygon layer.

Then style resulting layer and you'll get visualization like on the example.

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  • I have a dataset of polygons. See the updated post above with second picture – MapDeath Mar 5 '20 at 2:10

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