“Cluster Points conducts spatial clustering of points based on their mutual distance to each other.”
Point cluster renderers are used frequently in web mapping applications to condense multiple overlapping or nearby points into a single rendered marker for clarity. The clusters that are generated shows the number of items in each cluster, and as a user pans the map the clusters adjust based on the view. This makes it more efficient to render highly condensed data and easier for users to understand the map.
Goal: To classify condensed point layer using Point Cluster
When using point cluster it draws the points in a cluster with each cluster labeled with the number of features. The point cluster uses a point distance tolerance to determine the proximity of features that can be grouped together. If the point has no neighbors it will be drawn using the default symbology of that point feature. Point clusters also support the following symbolization.
1) Single Symbol
2) Categorized render
3) Rule based render
4) Graduated render
Point clustering also supports using expression variables to achieve data defined symbol overrides for the cluster symbol.
@cluster_size: this will be set to the number of points contained within the current cluster. This variable could be used to scale the size of the rendered cluster marker, or used along with the font marker symbol to draw the number of clustered points inside the cluster marker, or even used with the ramp_color function to vary the color of the symbol.
@cluster_color: if all points contained within the current cluster share the same symbol color (ie, if they are from the same category class or graduated range), then the @cluster_color variable will be set to match this color. If the points are from mixed classes then @cluster_color will be null. This variable can be used along with data-defined colors to alter the appearance of a cluster to inherit the same color as the symbols contained within the cluster.
NB: Point cluster only works with single point geometry. If you have a multipoint table you will have to convert it to a single geometry type in order to use this render.
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