Dynamic Aggregation

The previous blog briefly introduced several important new features that became available for TatukGIS customers at the end of 2019. One of the new features, dynamic aggregation for vector layers, deserves further explanation.

Aggregation is the process of separating map data - typically a large quantity of densely packed shapes, often points - into groups based on location (and possibly also using attribute values) for the purpose of presenting the data in a simpler way for easier and faster visual analysis. The aggregation is dynamic because the process is repeated, on-the-fly, each time the map is redrawn, e.g., zoom change, extent change, or layer edition.

This useful functionality is provided in the TatukGIS Layer Properties dialog box, under section Aggregation.

Legend Control - Aggregation

This means the aggregation tools are readily available (without need for coding) to both DK developers and users of the desktop GIS Editor and free Viewer. Aggregation settings are saved to the project file.

TatukGIS offers three main types of aggregation:

  • binning,
  • clustering,
  • shape reduction.

The basics of the aggregation types are essentially the same. Differences relate to how the aggregated data is presented.

  • Binning presents the data using contiguous, equal-sized polygons (bins) distributed evenly across the map area, with each bin representing the number of original shapes contained within its area.
  • Clustering presents the data using a smaller number of clustered, virtual point shapes. Depending on the Threshold parameter, the original and clustered shapes may coexist on the map.
  • Shape reduction presents a representative subset of the original point shapes for more effective visualization.

What makes TatukGIS aggregation features stand out?

  • A multitude of methods using grid-based algorithms, but also other smart solutions such as moving average.
  • Possibility to use both:
    • screen units, such as pixel, points, etc.
    • map units, such as kilometers, miles, etc.
  • Compatibility with all coordinate systems, geographic and projected.

Demonstrating the power of this functionality, the following image presents aggregated locations of the world’s airports in three different ways:

  1. ClusteringMovingAverage method on the left portion of the map (the American continents).
  2. BinningHexagonFlat method with Radius in screen units (pixels) on the center portion of the map (Europe and Africa).
  3. BinningSquare method with Radius in map units (miles) on the right portion of the map (Asia and Australia).

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Posted: February 13, 2020
Filed under: DK, rendering