书名：Mastering Geospatial Development with QGIS 3.x
作者名：Shammunul Islam Simon Miles GISP Menke GISP Smith Jr. Luigi Pirelli GISP Van Hoesen
本章字数：392字
更新时间：2025-04-04 14:40:31

Point-displacement vector styling

The point-displacement vector style radially displaces points that lie within a set distance from each other so that they can be individually visualized. This vector style works best on data where points may be stacked on top of each other, thereby making it hard to see each point individually. This vector style only works with the point vector geometry type.

The following screenshot shows how the Point displacement style works by using the Single symbol renderer, which is applied to the Stacked Points.shp sample data. Each point within the Point distance tolerance value of at least one other point is displaced at a distance of the Circle radius modification value around a newly created center symbol.

In this example, three groups of circles have been displaced around a center symbol:

The Point displacement style parameters as shown in the preceding screenshot, provide multiple parameters to displace the points, set the sub-renderer, style the center symbol, and label the displaced points. Let's review the parameters that are unique to the point-displacement style:

Center symbol: This contains the style for the center symbol that is created at the location from where the point symbols are being displaced.
Renderer: This contains the renderer that styles the displaced points. Click on the Renderer settings button to access renderer settings.
Point distance tolerance: For each point, if another point (or points) is within this distance tolerance, then all of the points will be displaced. The tolerance can be specified in millimeters, pixels, or map units. If choosing map units, further configuration becomes available, allowing for displacement to only happen between certain scale ranges or at certain size ranges.
Placement method: This sets the method of placing the displaced points as either Ring or Concentric rings.
Outline width: This sets the outline pen width in millimeters, which visualizes the displacement ring value.
Outline color: This contains the outline pen color for the displacement ring.
Ring size adjustment: The number of additional millimeters that the points are displaced from the center symbol.

The Labels parameters applies to all points (displaced or not) in the vector data. It is important to use these label parameters, rather than the label parameters on the Labels tab of the Layer Properties window, because the labels set in the Labels tab will label the center symbol and not the displaced points.