Track history

Track history visualisation controls how previous positions are displayed in the map. History styling includes amount of history to include as well as regular appearance styling. Track history belongs to the "TrackSymbol" style category.

<stylecategory "TrackSymbol">
  ...
  <compositeitem "History">
    ...
  </compositeitem>
</stylecategory>

Limits

Limits the amount of history data fetched from the service and how much history is displayed in the map. If more than one limit item is set, the most limiting value is applied.

<compositeitem name="History">
  <compositeitem name="Limits">
    <valueitem name="MaxLength" value="<percentage of screen diagonal>"/>
    <valueitem name="MaxAge" value="<seconds>"/>
    <valueitem name="MaxCount" value="<history points>"/>
  </compositeitem>
  ...
</compositeitem>

Item	Description
MaxLength	Max length of history measured as percentage of screen diagonal. Note that this is an approximate measure and depends on active scale and projection.
MaxAge	Max age in seconds. Any history points older than this value will be discarded/filtered out
MaxCount	Max count of history points

Visual

History visual settings control graphical appearance of the track history.

        <compositeitem name="Visual">
          <valueitem name="DrawVectorCluster" value="false"/>
          <valueitem name="DrawGridCluster" value="true"/>
          <valueitem name="DrawLines" value="false"/>
          <valueitem name="Color" value="0,32,32,196"/>
          <valueitem name="FadedColor" value="0,32,32,32"/>
          <valueitem name="FadeTime" value="10"/>
          <valueitem name="LineThickness" value="3.0"/>
        </compositeitem>

Item	Description
DrawLines	If true, line with specified color, thickness and dash style is drawn between track history points
DrawGridCluster	If true, display gridded cluster data/heatmap representing the time spent in an area. Each grid cell accumulates "loiter time" for all tracks, grid properties are controlled using the history substyle named "Clustering" See below for details on clustering and heatmaps
DrawVectorCluster	If true, display circles representing the time spent in an area. Vector clusters are analysed individually for each track See below for details on clustering and heatmaps
Color	Color of history line
LineThickness	Thickness of history line in pixels
DashStyle	Used to set history line dash. It consists of a comma separated list decimal numbers, the first specifies length of dash in pixels, the second the length of the spacing between dashes, the third the next dash length and so on. The history visualisation below was created using <valueitem name="DashStyle" value="4,2,1,2" />

Heatmap and history clustering

History clustering is used to visualise activity and time spent in a region. Two main types of visualizations are available: grid cluster and vector cluster. Coloring and grid "blobs" are used to indicate the time spent in a specific region.

    <compositeitem name="History">
        <compositeitem name="Limits">
          ...
        </compositeitem>
        <compositeitem name="Visual">
            ...
        </compositeitem>
        <compositeitem name="Clustering">
          <valueitem name="AnalysisCount" value="100"/>
          <valueitem name="ClusterRadius" value="500"/>
          <valueitem name="GridCellSize" value="4"/>
          <valueitem name="GridSmearSize" value="13"/>
          <valueitem name="GridSmearTimeThreshold" value="240"/>
          <valueitem name="TimeScale" value="20"/>

          <compositeitem name="GridCluster1">
            <valueitem name="MinSeconds" value="1"/>
            <valueitem name="CellColor" value="255,255,255,[heatmap.grid.alpha]"/>
          </compositeitem>
          <compositeitem name="GridCluster2">
            <valueitem name="MinSeconds" value="120"/>
            <valueitem name="CellColor" value="128,255,128,[heatmap.grid.alpha]"/>
          </compositeitem>

          <compositeitem name="VectorCluster1">
            <valueitem name="MinSeconds" value="6"/>
            <valueitem name="LineColor" value="255,255,255,128"/>
            <valueitem name="FillColor" value="255,255,255,[heatmap.vector.alpha]"/>
          </compositeitem>
          <compositeitem name="VectorCluster2">
            <valueitem name="MinSeconds" value="15"/>
            <valueitem name="LineColor" value="255,255,255,128"/>
            <valueitem name="FillColor" value="128,255,128,[heatmap.vector.alpha]"/>
          </compositeitem>
        </compositeitem>
      </compositeitem>

General parameters:

Item	Description	Applies to
AnalysisCount	Number of history points examined to determine contributions to local maxima. Lower values (<100) increase performance. Higher numbers (>100) decrease performance, used to visualise repeated visits to same region, for instance multiple stops at same harbour	Vector
ClusterRadius [m]	Controls cluster analysis and cluster visualizations. Same size is used for all clusters	Vector }