Charts Explained: Heatmaps

Heat Map

They plot geographical coordinates overlayed with a color spectrum to communicate density, based on a continuous variable linked to the coordinates. Althought the term is not universally used in the GIS world, (also known as “intensity maps”, “point density interpolation” or “hot spot maps”), it’s now the most used to refer to these kind of maps.  This term has been used in statistical analysis for many years and today we can find it in many situations. With Quadrigram you can easily build effective heat maps.

What are Heat Maps good for?

Heat maps are incredibly useful in identifying patterns and in particular, as the name might suggest, ‘hot spots’; because of this they are increasingly being used in sports analysis for example.

How do they work?

Heat maps take non contiguous point data and display them as being continuous. This method is not appropriate for all data. While mapping elevation or temperature as a continuous surface would make sense, mapping data that do not vary continuously over space may not. Additionally, having too few points upon which to base the surface will typically lead to larger errors.

How do they work in Quadrigram?

You need to select the heat map chart located within the charts menu. You only need three data to build a heat map: Longitude, latitude and hot spot intensities that will determine the intensity of each point.

Then you have two parameters which are important for the shape and intensity, and they are:

– Hot spot action radius (a scaling factor)
– Hot spot base intensity (how much hot spot will fuse)

Below see a collection of images showing the process of building a heat map in Quadrigram.

Example: Public Bike Sharing spots in London city. Latitude and Longitude in one file and hourly activity in another file.

screenshot-from-2016-10-31-112347 screenshot-from-2016-10-31-112500 screenshot-from-2016-10-31-112617 screenshot-from-2016-10-31-112647 screenshot-from-2016-10-31-112842

Resources:
Cartographic Perspectives
Quadrigram tutorial build an animated map

 

 

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