I'm working on a mapping application. For a feature, we'd like users to have the ability to cross reference a few of our datasets. Initially, I was just displaying the overlapping area from the selected datasets, but this loses a lot of finer grain details. I'd like to display the individual datasets, if possible.

Solutions I can think of such as showing highlighted areas work fine in some cases, but start to become complicated and difficult to understand very quickly. I'd like to avoid something like this: enter image description here

My concerns are that it can be difficult to differentiate datasets that overlap very closely, and without color vision it can be very difficult to parse this image.

How should I tackle this issue while still providing at least some of this powerful functionality to the user?

The datasets I'm working with are all based around the Great Lakes area and relate to biological and geographical data. To simplify things (both for processing and preparing the data), we're just looking at Lake Erie as this feature is still under development. Here's some sample data: https://arcgis.lsa.umich.edu/arcgis/rest/services/IFR/glahf_dss_le_cdd/MapServer?f=jsapi https://arcgis.lsa.umich.edu/arcgis/rest/services/IFR/glahf_dss_le_circulation_magnitude/MapServer?f=jsapi

  • why do you want to avoid something like that? Commented Jan 19, 2016 at 16:12
  • 1
    My concern is that it can be hard for people with colorblindness to parse, and that for example the purple and blue datasets overlap very tightly and it's difficult to separate them. I'll edit this into the question for clarification.
    – two bugs
    Commented Jan 19, 2016 at 16:16
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    Can you be more specific about the geographic data you have? For example is it county based? Zip code? I have some ideas, but it's not clear from the above, what your data points are. Commented Mar 26, 2016 at 8:09
  • You'll probably need some kind of zooming in/out functionality to go with whatever else you'll need to implement, but it is hard to comment without getting a better feel for the data. Some sample datasets/data points would be helpful here.
    – Michael Lai
    Commented Mar 29, 2016 at 0:37
  • Using colors to categorize something can be confusing, I will add filter function and set a major color as default.
    – YogaPanda
    Commented Mar 30, 2016 at 20:51

2 Answers 2


Instead of cluttering your map by trying to layer your data sets directly on the map, why not try the reverse approach and abstract your data/images from your map, and give user the option to compare on the map directly.

As a really rough example, something like this?

enter image description here

  • Great suggestions! I'll play around with them and see how I can get them looking. I'm a bit concerned about the screen real estate, but that's going to be a problem no matter what solution I pursue.
    – two bugs
    Commented Mar 31, 2016 at 13:16

Here's what I've gone with so far:

enter image description here

I decided to go with a legend, clearly signifying which dataset is which and allowing users to toggle them on or off at will. I've done some pretty simple usability testing so far and the results are looking positive, but I'm sure there is room for improvement.

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