023] How to Close Gaps Between Adjacent Features in Global Mapper Vector Layers

Align vertices and eliminate topological gaps in vector data with one click.

This tutorial explores the "Close Gaps Between Adjacent Features" function in Global Mapper, a specialized tool for fixing tiny, unintended gaps between lines and polygons—essential for cadastral mapping and engineering blueprints.

Today, we will explore the final item in the layer context menu that applies to all vector layers: "Close Gaps Between Adjacent Features..."

In digital mapping projects, especially when dealing with cadastral maps or engineering blueprints, you might encounter tiny, unintended gaps between lines or polygons. The "Close Gaps Between Adjacent Features" function is designed to eliminate these gaps by aligning the positions of vertices (vertex snapping).

While this isn't a tool you'll use every single day, it is incredibly efficient for shortening the time spent manually zooming in and out to align boundary lines or design elements.

How to Close Gaps Between Features in Global Mapper

1. Prepare Your Layers

First, open the project file we worked on in the previous lesson. In the Control Center, make sure to activate both the 'Line' (선) and 'Area' (면) layers. These will be our target layers for today's demonstration.

Map view showing a dashed purple line and a solid blue polygon with a visible gap between them
img 1 : Map view showing a dashed purple line and a solid blue polygon with a visible gap between them

2. Access the Function

Right-click on the selected layers in the Control Center to bring up the context menu. Navigate down and select "Close Gaps Between Adjacent Features..."

Context menu in Global Mapper highlighting the 'Close Gaps Between Adjacent Features' option
img 2 : Context menu in Global Mapper 'Close Gaps Between Adjacent Features'

3. Select Target Layers

A "Select Layers" dialog box will appear. Here, you need to confirm which layers you want the operation to apply to. Select both the 'Line' and 'Area' layers and click OK.

'Select Layers' dialog box with 'Line' and 'Area' layers checked
img 3 : 'Select Layers' dialog box with '선' and '면' layers checked

4. Specify Distance and Snapping Rules

Next, the "Specify Distance" window will pop up. This is a crucial step where you define how the snapping occurs:

'Specify Distance' dialog box with '60' entered as the gap distance
img 4 : 'Specify Distance' dialog box with '60' entered as the gap distance
  • Gap Distance: The number you enter represents the maximum distance between vertices. Any vertices within this specified range will be snapped together to close the gap.
  • Process each layer separate from the others:
    • If checked: The software only analyzes and snaps vertices within the same layer.
    • If unchecked: The software analyzes vertex distances across different layers.

5. Analyze the Gap Distance

Before confirming, let's look at the map scale. In this example, looking at the scale bar, the distance between the vertices of our features is several dozen meters.

Map view with a scale bar showing intervals from 0m to 300m for distance reference
img 5 : Map view with a scale bar showing intervals from 0m to 300m for distance reference

We will enter 60m as our threshold and click OK.

Gap Closing Results in Global Mapper

Map view showing the resulting change where the line vertex has snapped to the area boundary
img 6 : Map view showing the resulting change where the line vertex has snapped to the area boundary

As you can see, the shape of the features has changed. The vertices were automatically snapped together, effectively closing the gap.

Important Limitations of the Gap Closing Tool

This tool is not ideal for every situation is that the results can sometimes be unpredictable. The function doesn't allow you to set a "base" or "reference" layer that stays fixed while other layers move. Instead, it simply moves all relevant vertices to a calculated meeting point. Use this tool when you have many small gaps and need a quick fix, but always review the results to ensure the geometry still meets your project requirements.

Conclusion

This concludes our walkthrough of the layer-specific context menus in Global Mapper. Understanding how these menus change based on the characteristics of the data within the layer will make your project management much more intuitive.

That’s all for today! Happy mapping!

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