[018] Global Mapper - Elevation Layer 02: Advanced Processing

We continue exploring the Elevation Layer context menu.

1. Create Area Feature from Equal Values...

This function can be used for both elevation and raster layers. It groups elements with the same values into a single polygon.

When you run Create Area Feature from Equal Values..., a list of compatible layers will be displayed. Select the elevation layer and click OK. A detailed setup window will then appear.

• Layer Description: Sets the name for the new layer to be created.
• Value Attribute Name: Sets the attribute name that will store the elevation value for the generated polygons.
• Set up Allowed Color Fuzziness: This applies to raster layers, which we will cover later.
• Set up Allowed Elevation Fuzziness: This is specifically for elevation layers.
• Maximum Match Distance: This represents the $\pm$ range value. For example, if you enter "5", it will group elevation values within a $-5$m to $+5$m range into a single polygon. This means the resulting polygon will represent a 10m elevation range. The smaller this value, the more polygons will be generated.

Enter your settings as shown above and click OK.

The elevation polygons have been created. Let's look at the information for one of them.

By selecting the Feature Info Tool (Alt+P) and clicking the red polygon in the center, we can see its perimeter, area, and the fact that it encompasses an elevation range from 105m to 115m. This is used when you need a simplified representation of elevation.

2. Vectorize Raster

While Create Area Feature from Equal Values... creates polygons for all values in a given area, Vectorize Raster allows you to select a specific range and convert it into a polygon.

Upon selecting Vectorize Raster, a setup window appears.

• Layer Description: Enter the name for the new layer.
• Elevation/Slope: Enter the specific elevation (or slope) range you want to convert into a polygon.
• Discard Areas Smaller than: Polygons with an area smaller than the specified value will not be created.

Clicking OK will generate a polygon covering only that specific elevation range.

Simple, isn't it? It's worth noting that by changing the shader in Global Mapper, you can also differentiate slope or aspect into polygons using these same methods.

3. Create Mesh Features from Terrain...

Global Mapper can create both DEM and TIN simultaneously from digital topographic maps. However, if you have imported a DEM from elsewhere and want to create a TIN, you must convert the DEM to a Mesh.

That function is Create Mesh Features from Terrain.

Executing this menu brings up the layer selection window followed by the detailed settings.

• Vertical Units: The unit of measurement (obviously Meters).
• Mesh Grid Spacing: This determines the resolution. For example, setting it to 40x40m means the elevation layer will be analyzed in 40m segments. Smaller values create more accurate meshes.
• Texture Options: Determines whether to apply the colors of the current layer to the mesh and how detailed that application should be. Smaller values will apply the original layer's colors more accurately.

Click OK to generate the mesh layer.

The mesh layer (TIN) has been successfully registered. Since the remaining items are not directly related to analysis, I will conclude the elevation layer menus here.

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Next, we will explore the menus for raster layers.

That's all for today~