When designing map colors, four color modes are available: RGB mode, CMYK mode, HSB mode, and LAB Mode. For maps intended for computer display or web map services, RGB mode is recommended. For printed maps, CMYK mode (the standard printing color mode) should be used. In HSB mode, H, S, and B represent Hue, Saturation, and Brightness respectively - a color model defined from visual perception. Higher S and B values indicate greater saturation and brightness, resulting in more vivid colors. LAB Mode addresses the limitations of RGB and CMYK, consisting of three channels: L for lightness, and A/B for color channels. The A channel ranges from dark green (low brightness) to gray (mid brightness) to bright pink (high brightness). The B channel spans from dark blue (low brightness) to gray (mid brightness) to yellow (high brightness). This combination produces vibrant colors. The choice of color mode should be determined by specific requirements.
In the following examples, color representations may use different mode values depending on context, not limited to fixed color modes. Practical cartography typically involves three types of point symbol scenarios.
System Symbol
For large POI datasets without clear classification, system symbols (square/circle in SuperMap) are typically used. Symbol size should adapt to map requirements, while color selection depends on map background. Light backgrounds pair well with intense colors, whereas rich backgrounds require high-purity, saturated colors. As shown:
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| Figure: Contrast Between Map Background and Symbol Colors |
Mainstream online maps (Google, Baidu, Tencent) prioritize harmonious aesthetics over vivid colors, often using low-saturation grays for large areas like administrative regions. When adopting similar background schemes, use corresponding low-saturation colors (Note: S=0 in HSB produces gray).
Vector Symbol
Vector symbols with specific meanings, fixed sizes, and standardized colors are common in professional maps (e.g., surveying, hydraulic facilities). As illustrated:
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| Figure: Vector Symbol Example |
Typically, main elements of vector symbols use high-purity colors. Subtypes within the same category may employ different hues (e.g., red for floodgates vs green for drainage gates). Industry symbols have strict size and color specifications that must be followed during creation or style configuration.
Raster Symbol
Raster symbols are widely used in digital mapping for pictorial representation. Colors should approximate real-world counterparts (e.g., green for parks, blue/orange for gas stations). Example:
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| Figure: Raster Symbol Example |
While not absolute, raster colors should align with common perceptions (e.g., red for government buildings). Size and color must coordinate with overall map design. When uncertain, use uniform colors like gray (S=0 in HSB).
SuperMap iDesktopX requires raster symbols created in graphic software (e.g., Photoshop) with predefined colors to avoid rework. Note: Raster symbols typically feature white circular backgrounds for contrast. In digital maps, symbols are often accompanied by labels - another reason why default symbols remain practical.
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| Figure: Symbol Application in Maps |
Related Topics
Basic Characteristics of Color and Color Psychology
Color Design for Linear Symbols
Color Design for Areal Features