Heat Map

Feature Description

A heat map visually presents data (e.g., population distribution, density, trends) through color gradients, ideal for displaying density, frequency, temperature, and other complex data patterns.

Only point datasets are supported for heat map creation. Each discrete point establishes a buffer zone filled with progressive grayscale gradients (0-255) from center to periphery. Overlapping buffer zones accumulate grayscale values - higher accumulations indicate "hotter" areas. These values map to a 256-color spectrum (e.g., rainbow colors), typically using cool-to-warm hues to represent low-to-high density. Alpha Channel must be enabled during rendering.

Heat maps not only reflect relative point density but can also use attribute weighting (e.g., point weights) for precise density visualization. As dynamic raster surfaces, they update with map scaling - e.g., a national tourist attraction heat map can reveal provincial-level traffic patterns when zoomed.

Feature Entry

Select target point data layer in layer manager:

  • Thematic Map tab -> Aggregation Map group -> Click Heat Map button
  • Right-click layer, choose Create Thematic Map... from context menu -> Select Aggregation Map->Heat Map in dialog

Steps

  1. A heat map thematic layer will be generated in layer manager
  2. Right-click heat map layer -> Select Modify Thematic Map -> Layer Properties panel appears
  3. Modify basic settings in Layer Properties panel:
    • Display Control: Configure layer visibility, naming, transparency, and scale ranges
      • Visibility: Toggle visibility for entire layer group
      • Layer Name: Unique identifier for layer group (read-only)
      • Layer Caption: Editable display name in layer manager
      • Transparency: 0 (opaque) to 100 (fully transparent)
      • Minimum Visible Scale: Layer group hides when zoomed beyond this scale
      • Maximum Visible Scale: Layer group hides when zoomed within this scale
    • Change Dataset: Select new datasource/dataset via dropdowns. See: Change Dataset
  4. Parameters: Configure core heat map properties:
    • Kernel Radius: Influence radius for discrete points
      • Measured in screen coordinates
      • Creates grayscale buffers (0-255) radiating from points
      • Overlapping buffers accumulate grayscale values
      • Color mapping based on accumulated values
    • Weight Field: Numerical field modifying point influence

      Weight values multiply buffer influence coefficients (e.g., weight=10 makes buffer 10x more influential)

      Note: Weight field must be numerical
    • Aggregate: Aggregation method when using weight field (Average/Count/Max/Min/Sum)
    • Color Scheme: Predefined color gradients from dropdown
    • Minimum Color Transparency: Default 100 (fully transparent)
    • Maximum Color Transparency: Default 10
    • Color Mode: HSB/RGB selection
    • Color Gradient Blur: Adjusts color transition smoothness
    • Maximum Color Weight: Controls color distribution in gradient
    • Original Point Visible Scale: Set visibility scale range for source points
      • System Default Scale: Auto-calculated visibility threshold
      • Set to Current Scale: Use current map scale as threshold
    • Extremum Value Settings: Define value-color mapping ranges
      • View Extremum: Use current viewport's min/max values
      • System Extremum: Auto-calculated based on map scale
      • Custom Extremum: Manual value specification
      • Display Filter: SQL-based point filtering. See: SQL Query Builder
  5. Complete heat map configuration with above parameters

Application Example

Case Study

Visualizing national distribution of cultural/educational institutions using point data.

Data Requirements

  • Point data: Cultural/educational institutions with attributes
  • Basemap data: Chinese administrative boundaries, national borders
  • Supplementary data: Chinese highway network
Notes:

Sample data location: SuperMapsample data SampleData\AggregationMap\HeatMap. Requires separate installation package. See: Obtain Sample Data

Workflow

  1. Open HeatMap.smwuworkspace
  2. Prepare basemap with administrative layers and single symbol labeling
  3. Add institution point data -> Right-click to create heat map
  4. Configure kernel radius, weight field, color parameters
  5. Adjust gradient blur and extremum values for optimal visualization
Figure: Heat Map of National Educational Institutions Distribution

Related Topics

Grid Map

Dynamic Aggregation Map

Regional Aggregation Map