3. Symbology¶

Goal: Style any layer with the right symbology type for the data — single, unique values, graduated colors, dot density, or charts.

Open the Symbology pane¶

Right-click a layer → Symbology. Or Feature Layer ribbon → Symbology dropdown.

The 7 symbology types¶

flowchart TD
    A{Your data} --> B[All same?]
    B -->|Yes| Single[Single Symbol]
    A --> C[Categories]
    C --> Unique[Unique Values]
    C --> UnMany[Unique Values<br/>many fields]
    A --> D[Numeric]
    D --> GC[Graduated Colors<br/>e.g., income choropleth]
    D --> GS[Graduated Symbols<br/>e.g., point sizes]
    D --> PV[Proportional Symbols<br/>continuous size]
    D --> DD[Dot Density<br/>e.g., population]
    D --> Heat[Heatmap<br/>kernel density of points]
    A --> E[Charts]
    E --> Pie[Bar / Pie chart symbology]

    classDef root fill:#4338ca,stroke:#312e81,color:#fff
    class A root

Picking a classification (numeric)¶

Open Symbology → Method:

→ Read the Cartography page for design rules.

Color palettes¶

Open the Color scheme dropdown — it's powered by ColorBrewer + Esri palettes.

• Sequential for quantity (light→dark)
• Diverging for ±values (red→white→blue)
• Categorical for categories (Set1, Set2)

Tick Show all to see them all. Tick Color blind safe to filter accessible options.

Symbol galleries¶

For points especially, the Symbol Gallery has hundreds of pre-made markers (transportation, emergency, retail). Open the symbol → Gallery tab.

Levels of symbology¶

For complex maps (e.g., overpass road networks), use Symbol Levels to control which symbol draws on top of which. Symbology pane → … → Switch to symbol levels view.

Pyramid: a clean starter symbology¶

For a polygon layer:

1. Outline: 0.5 pt, color = darker version of fill.
2. Fill: a light, sequential ramp.
3. 4–5 classes max.
4. Make sure the legend labels are human readable (not raw numbers).

For a point layer:

1. Marker: 6–8 pt, white outline 0.5 pt, distinct fill.
2. No drop shadow.
3. Visible at multiple zoom levels.

For a line layer:

1. Major roads: 1.0 pt, primary color.
2. Minor roads: 0.5 pt, neutral.
3. No double-line outlines unless you really need them.

Practice¶

→ Next: Labeling.