Section : . Penyimbolan

Module : . Heatmaps ❗

Heat maps in Context

“Heat map visualizes hotspots in the distribution of features on the map i.e. dense areas will be highlighted in a heat map, based on the parameters you use for processing it”

In this module, we explore heat maps as a point symbolisation technique.

You try:

Goal: To learn creating heat maps as a symbolisation technique

Data: heatmaps/earthquake.csv and ne_10m_admin_0_countries from heatmaps/ne.sqlite.

  • Load the earthquake layer as a spatial layer.
  • Load the ne_10m_admin layer
  • Change the country layer transparency as specified
  • Change the layer order to put the point layer on top
  • Open the properties of the point layer and click the style tab.
  • Change to the specified render type
  • Choose the specified colour ramp
  • Apply the changes and observer the map
  • Why does the whole map colour change?
  • Edit the colour ramp. Make colour 1 transparent.
  • Apply the changes and observer.
  • Open the properties of the point layer and change rendering quality to fastest. Observe the changes.
  • Change the weight points by option to use the specified attribute.

NB: What can you infer about the intensity of the heat map in relation to deaths?

Name Expectation

Render

❗

Heat map

Country transparency

❗

70

Colour ramps

❗

Spectral

Attribute

❗

Deaths

More about

Heat maps use colour to communicate relationships between data values that would be difficult to understand if presented numerically in a spreadsheet or attribute table. A colour ramp helps to visualise a heat map with low values having colours at the bottom of the colour ramp and high intensity values corresponding to darker values on the colour ramp.

Check your knowledge:

  1. When would it be useful to use a colour ramp:❗

    1. To depict how a player was behaving during a soccer match.
    2. To show that the layer being represented is a vector layer.
    3. Heat maps can also be applied to raster data.

  2. Which statement is false:❗

    1. A colour ramp is used to show variation in a phenomena of interest
    2. Heat maps are extensively used by scientist
    3. Heat map points can be weighted by a discrete column

  3. A colour ramp is a type of vector analysis:❗

    1. True
    2. False

Further reading:

Download the sample data for the lesson.