[019] Global Mapper - Raster Layer

Today, we will cover the context menu for Raster Layers. Open your previous project and activate the 'Image' layer.

"Before we begin, if you missed the previous session, check it out here:"

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

Control Center window with the "Image" layer selected] [Image 26: Satellite image view showing agricultural land

Let's look at the menus applicable to raster layers. You'll notice they are similar to those of elevation layers, but a few items are missing:

Raster Layter's Context Menus

• Create Workspace File from Selected Layer(s)...
• EXPORT - Export Layer(s) to New File...
• MAP CATALOG - Add Selected Layer(s) to Map Catalog...
• BBOX/COVERAGES - Create Layer Coverage Box/Polygon Area Features
• Create Area Features from Equal Values...
• Vectorize Raster
• Link External Metadata File
• Save List of Layers to Text File...
• Set Background Color for Layer in Control Center

The usage is mostly the same as with elevation layers, so let's focus on Create Area Features from Equal Values... for images.

1. Create Area Features from Equal Values (Raster)

Selecting the "이미지" layer in the "Select Layers" dialog

After selecting the layer and clicking OK, the setup screen appears. Here, you'll focus on Color Fuzziness instead of elevation.

Setup window highlighting "Maximum Match Distance" under "Set up Allowed Color Fuzziness"

• Maximum Match Distance: This indicates the range of color values (0–256) to be grouped into a single polygon.
  • 0: Separates polygons even if the color value changes by a single step (Exact match).
  • 256: Groups all colors in the entire range into one giant polygon.
  The higher the number, the larger the resulting polygon "chunks" will be.
• Select Color(s) to Create Areas For: Use this to isolate and vectorize only specific colors.

Once you click OK with these settings, an Image Areas layer is created, and you'll see small polygons generated on the main map.

Main map view overlaid with thousands of small, color-based polygons

Feature Information for a selected image polygon showing its RGB value (e.g., 84, 105, 84)

2. Vectorizing a Specific Color

Now, let's learn how to create polygons for a specific color only. In the setup window, select Only Selected Color(s).

Choosing the "Only Selected Color(s)" radio button in the setup menu

A color picker will appear. While you can choose from preset basic colors, clicking Pick Color from Map allows you to select a color directly from your current satellite image.

olor picker dialog with the "Pick Color from Map" button highlighted

User clicking on a specific bluish rooftop in the satellite image to sample its color

The sampled color now displayed in the Color picker window

Final check of settings with a "Maximum Match Distance" of 40 for the selected color

By increasing the Maximum Match Distance (e.g., to 40) and clicking OK, polygons will be generated only for the parts of the image that fall within that specific color range.

Main map showing polygons only generated for the targeted specific color areas

3. Vectorize Raster (Raster Setup)

The Vectorize Raster option for images is slightly different in its setup from the elevation version. I'll briefly explain the settings so you can try it yourself.

"Setup Vectorize" window for a raster layer

• Select Color(s): Choose the target color via the picker or the map.
• Matching: Determines the inclusion range based on the selected color. Moving the slider toward Exact narrows the range, while moving it toward Fuzzy broadens it.
• Color Matching Preview: Shows a preview of the result. However, the preview window is often too small to be truly useful.

This concludes our exploration of the Raster Layer context menu.

That's all for today~

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

[020] Global Mapper - Point Layer: Calculate/Copy Attribute Value(s)...