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I've recently been working on a thematic map which shows a large area at small scale, containing a number of different polygon layers showing different feature classes (unfortunately I can't share the draft map). One thing I'm struggling with on this map is how to effectively highlight the presence of small area polygons. These tend to get lost among the larger area polygons, but they are important and need to be immediately noticeable on the final map.

I've tried a number of techniques for highlighting these, but without success:

  1. Using multiple inset maps at a larger scale isn't an option due to the number of these small area polygons on the map. The final product also needs to fit on a single page, so space is a premium.
  2. Labeling them also isn't an option, again due to the number of these problematic features.
  3. I've tried adding a larger 'halo' style border under these polygons, as a way of making them visually larger while still attempting to give a good indication of their actual size. It's probably the closest I've come, but I'm not that happy with how this looks (it's more cluttered and confusing then I'd like).
  4. I also tried swapping the feature symbol from a polygon to a point symbol when the feature is below a certain size threshold - but I think this makes for a less readable map at first viewing. I'd also like to have some way to give an indication of the actual size of the smaller features still.

So now I'm after tips or tricks in how to visually increase the prominence of these features so that they stand out more on the finished map.

ndawson
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  • mmh...I guess the process of cartographic generalization has come a long way and has some rules for visual improvement for a good reason ,) like there has to be some sort of selection and there are minimal visual dimensions for features to keep, or raise the need to transform them (e.g. to points/labels). labels/point symbols also offer multiple levels of information, like their size or shape, with labels having the advantage to be variable in position...I would say, as an opinion, to stick to some rules of thumb and explore different approaches than simply try to fit in those tiny polygons... – geozelot Jun 21 '17 at 08:13
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    If they are important but small, can you make their importance the main attribute for styling? Then you could emphasize them by color. Alternatively maybe a cartogram? – bugmenot123 Jun 21 '17 at 08:59
  • Can you be more specific about the use case? I would imagine a summary table or chart may be the most useful way to draw attention to them if you don't want to clutter your map. Another potential option (but unlikely to be sufficient on it's own) is to work with blending in QGIS. Well introduced in this blog post. – RoperMaps Jun 21 '17 at 09:43
  • How about using symbols for small polygons as you did but changing the size of symbols by the area? – user30184 Jun 21 '17 at 16:09

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