Heatmap Creation
Definition
Heatmap creation is the process of visualizing density or intensity by smoothing point or event data into a continuous surface. The technique highlights hot spots and gradients without exposing individual records. In GIS, kernel density estimation and hex binning are common approaches. Choosing bandwidth, cell size, and normalization determines how patterns appear. Good heatmaps respect privacy, state what the underlying measure is, and avoid implying precision that is not present in the data. Use perceptually uniform color ramps and test on color vision deficiency simulators. Avoid projecting raw counts when populations vary greatly across space. Annotate bandwidth, time window, and data sources in the legend. For web maps, decay older events over time so hotspots reflect current conditions without hiding long term structure.
Application
Police departments visualize calls for service, retailers examine foot traffic from mobile panels, transportation planners show scooter parking violations, and epidemiologists monitor clinic visits. Product teams use heatmaps in dashboards to guide user experience design and incident response. When paired with basemaps that minimize distraction, heatmaps communicate complex patterns at a glance for non technical audiences.
FAQ
How do heatmaps differ from choropleth maps?
Heatmaps derive a surface from points or events and are not limited by administrative boundaries. Choropleths aggregate to polygons and can hide within unit variation.
What is the right bandwidth for a kernel density map?
There is no universal answer. Test multiple values and validate against domain knowledge. Use cross validation or information criteria when you need a defensible choice.
How can heatmaps protect privacy?
Use aggregation thresholds, add noise, and avoid publishing small area extremes. Time aggregation further reduces re identification risk when events are sensitive.
When should a heatmap not be used?
When precise counts per area or exact locations are required. Heatmaps are for pattern recognition, not for allocating resources to specific addresses.