001] Global Mapper - Creating DEMs

This is the first session of the Global Mapper series.

Among the many things you can create using GIS software, I plan to cover topics essential for preparing landscape-related reports, such as:

• Creating a DEM (Digital Elevation Model)
• Using Online Maps
• Contour, Slope, and Aspect Analysis
• Path Profiling (Terrain Sections)
• Viewshed Analysis
• Using the Map Layout Editor for saving images in Global Mapper

As with my CityEngine series, I believe in getting started first to build a framework as posts accumulate. I won't go into every tiny detail right from the start; instead, I will provide deeper explanations and supplementary information as we progress.

First, you'll need to download the trial version.

If you visit the Blue Marble Geographics website, you will see a menu for a "Start Free Trial." Please note that personal emails (Naver, Gmail, etc.) are generally not accepted; you must use an email associated with a company or an educational institution. Once your email is confirmed, download and install the software before proceeding with the content below.

As you follow along, try comparing the workflow with other GIS software. This is the "highlight" of using Global Mapper.

▲ Check out the step-by-step video tutorial for creating DEMs!

Now, let's begin creating a DEM.

1. Importing the Digital Topographic Map

One of the greatest advantages of Global Mapper is its ability to import an incredibly wide range of file formats.

We will import a continuous digital topographic map in SHP format downloaded from the National Spatial Data Infrastructure portal. When downloaded, these maps are typically saved as a single ZIP file. Global Mapper is smart enough to load the data even if it is still compressed in a ZIP folder.

The result of the import is as follows:

These are the contour line and elevation point data. In the Control Center, you can see the currently used data managed as layers.

2. Verifying Elevation Attributes for Each Layer

To create a DEM, you need to know which attribute in the digital map contains the height values. Select the Digitizer Tool (the pencil icon) from the top menu and double-click on a contour line.

A "Feature Info" window will appear as shown below.

The value belonging to the CONT attribute represents the elevation figure. Once you've confirmed that the contour layer uses "CONT" for elevation, close the window.

Now, select the layer in the Control Center, right-click, and select Options.

In the options window that appears:

Go to the Elevations tab and select "CONT" from the "Get Elevations From Attribute Value" list box, then click Apply. This tells Global Mapper to recognize the "CONT" value as the elevation data.

3. Generating the Elevation Grid (DEM)

Now it's time to generate the DEM Grid. Right-click on the selected layer and choose Analysis -> Grid.

Select the layers you want to use for the DEM and click OK. The Grid Creation Options window will appear.

While it varies depending on the site size, for a radius of about 1km, I typically set the Grid Spacing to Use to 5 meters. Check the other options as shown in the image above and then select the Grid Bounds tab.

Here you can set the area for the DEM generation. All Loaded Data is used to convert the entire selected layer into a DEM. By choosing Draw a Box, you can select only a specific rectangular area.

Click and drag the mouse to define the appropriate area, then click OK. The selected area will now be indicated on the main screen.

Click OK to proceed. The DEM is now created!

Let's check the result in 3D. Click the cube icon with "3D" on it in the top menu.

A 3D screen that you can rotate and inspect will appear. The process is complete!

I've only explained the very basics for now, despite the many options and functions available for DEM generation. I will explain the details as needed as we move forward with the lectures.

That's all for today~

"In the next session, we'll dive deeper into more advanced features. Stay tuned!"

003] Global Mapper - Terrain Analysis, DEM Creation, and Raster Reclassification