Polygon areas cover extensive regions, immediately capturing readers' visual attention and influencing their aesthetic perception. Successful color design conveys rich geographical information through minimal cartographic elements, enabling clear, complete, and accurate expression of map purposes and design intentions. Therefore, color selection for polygon areas should emphasize hierarchical differentiation through varied color values.
Different polygon areas represent distinct geographical properties. Color schemes should reflect these characteristics through differentiation from other symbols. Common polygon areas include vegetation, water bodies, and built-up areas (residential zones). Typically, vegetation uses green tones while water bodies adopt blue hues. Built-up areas may employ different color schemes depending on map purposes. For example:
- Topographic maps: Gray (K=20)
- Administrative maps: Distinct color schemes for different jurisdictions:
- Light pink (M=25)
- Light yellow (Y=30)
- Light orange (M=15, Y=30)
- Light purple (C=22, M=28)
- Light green (C=15, Y=20)
 |
| Figure: Color Design of Different Built-up Areas |
When overlaying polygon layers with other map layers, occlusion may occur. Practical solutions include:
- Setting color transparency for semi-transparent effects
- Enabling "Alpha Channel" in map properties
- Adjusting A (Alpha) value in RGB color settings when working with image data overlays
Alpha value range: 0-100 (0: Fully transparent; 100: Fully opaque)
 |
| Figure: Transparency Adjustment via Alpha Value |
Related Topics:
Basic Characteristics of Color and Color Psychology
Color Design for Point Symbols
Color Design for Linear Symbols