CUBIZEN: Global Mapper, CityEngine & Creative Tech

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

Let's review the context menu functions available for Raster Layers. You'll notice they are similar to those of elevation layers, but a few items are missing:

• 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

Most functions work similarly to those used with Elevation Layers.

1. Creating Area Features from Similar Colors

After selecting the layer and clicking OK, the setup screen appears. Here, you'll work with Color Fuzziness settings instead of elevation values.

• 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.
  Higher values produce larger merged polygon areas.
• Select Color(s) to Create Areas For: Use this to isolate and vectorize only specific colors.

Practical Applications of Color-Based Vectorization

Extracting vector polygons based on raster colors is incredibly useful for preliminary site surveys and environmental mapping. For example, when analyzing high-resolution satellite imagery without land cover data, you can isolate dense vegetation by targeting specific green RGB hex codes, or identify roof types by capturing artificial blue or gray tones.

However, you must keep in mind that shadows cast by buildings or clouds can dramatically alter the underlying pixel values. A roof in direct sunlight and the same roof covered in shadow will have completely different RGB signatures. Therefore, setting an appropriate color fuzziness range is the most critical step to ensure that minor lighting variations do not break a single land asset into dozens of fragmented polygons.

How Maximum Match Distance Influences Grid Resolution

When tweaking the Maximum Match Distance, consider the ultimate scale of your GIS project. If your objective is a high-precision urban analysis—such as identifying individual building footprints or precise road markers—keeping the value low (between 5 and 15) is ideal, though it will generate a massive number of micro-polygons that can slow down your system.

Conversely, for macro-scale zoning, such as defining general forestry boundaries or regional water bodies, increasing the distance factor up to 50 or 60 will automatically dissolve negligible pixel gaps. This creates smoother, continuous boundary lines that are much easier to export and manage in secondary CAD or urban modeling applications like Esri CityEngine.

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

2. Creating Area Features from a Selected Color

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

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.

By increasing the Maximum Match Distance (e.g., to 40) and clicking OK, polygons will be created only for image regions that match the selected color range.

3. Understanding Vectorize Raster Settings

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.

• 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 may be too small for detailed inspection.

This concludes our exploration of the Raster Layer context menu.