CUBIZEN: Global Mapper, CityEngine & Creative Tech

Today, we will learn how to create a DEM (Digital Elevation Model) and perform terrain analysis in Global Mapper using contour data. If you are accustomed to ESRI products or Q-GIS, you might find Global Mapper's output slightly different at first, but its intuitive workflow is incredibly powerful once you get used to it.

1. Importing Contour Data into Global Mapper

The first step in terrain analysis is generating a Digital Elevation Model (DEM) from contour data. You can use your own data or any standard digital topographic map files.

Download: Terrain_data.zip (Verified and safe file for download.)

Opening Digital Topographic Data

To begin, open your contour file in Global Mapper by navigating to File > Open Data File(s).

Once the file is loaded, you will see the contour lines displayed on the screen. However, the default colors might not be very visible depending on your workspace settings.

Adjusting Contour Line Styles for Better Visibility

To make the analysis easier, let's change the color of the contour lines. In the Control Center, select the contour layer, right-click, and choose Options.

In the Vector Options window, go to the Line Styles tab and click on Select Style.

From the Select Line Style window, click on Color, choose a highly visible color (like dark grey or black), and click OK to apply the changes.

Now the contour lines are much clearer and easier to work with.

2. Generating the Elevation Grid (DEM)

Now that we have our vector data, we need to convert it into a grid (DEM). The most critical step here is assigning the elevation attribute.

Assigning Elevation Attributes

Right-click the layer in the Control Center > Options > Elevations. Select the attribute field that contains the elevation data (usually 'CONT') and click Apply.

Generating the Elevation Grid (DEM)

Next, right-click the layer again, and navigate to Analysis > Create Elevation Grid.

The Grid Creation Options window will appear. For basic analysis, you can simply click OK with the default settings.

A DEM is now generated, showing the terrain as a black-and-white gradient by default.

3. Adding an Elevation Legend to the DEM

To understand the elevation range, we should add a legend to the screen. Go to View > Workspace Layout Options > Elevation Legend.

In the Configuration window, set it as follows:

• Unit: Select Metric (meters) for standard measurements.
• Transparency: Set to Opaque (100%) for better visibility.
• Legend Range: Choose Data Extents to show the full range of your terrain.

Now a legend appears on the left, showing that our terrain ranges from 65m to 135m.

4. Applying Terrain Shaders and Color Ramps

While black-and-white is functional, most people prefer the standard topographic color scheme (red for high, blue for low). Global Mapper provides various pre-set Shaders.

Using the Atlas Shader

On the top toolbar, click the drop-down menu next to the mountain icon (Shader list) and select Atlas Shader.

The map now displays a more familiar topographic color scheme.

5. Raster Reclassification and Elevation Statistics

If you need to know the exact area occupied by specific elevation ranges, use Raster Reclassification. Navigate to Raster Analysis > Raster Reclassification.

Analyzing Elevation Distribution with Bins

In the reclassification window, you can set the Number of Bins (how many levels to divide the data into) and see the area distribution in a bar graph.

Exporting Terrain Statistics to CSV

By clicking Display in Graph Window, you can view the distribution in a larger window and save it as an image or export the data as a CSV file for use in Excel.

6. Performing Slope and Aspect Analysis

Performing Slope (gradient) and Aspect (slope direction) analysis is just as simple. You only need to switch the Shader.

Using the Slope Shader

Once you change the shader, the map updates instantly to show the slope distribution.

Conclusion

Global Mapper makes terrain analysis intuitive and fast. Whether you are generating a DEM or conducting advanced slope studies, the key lies in understanding the Shader options and Raster Analysis tools. Give it a try with your own topographic data!