Module 02: Layers & Symbology

Layers organize spatial data by theme. Each layer has a geometry type, visual style, and optional form schema. This module covers creating layers, styling them, labeling features, and applying field-based symbology.

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1. Creating a New Layer

1. Navigate to the Layer Manager (tap "Layers" in the bottom navigation).
2. Tap the + New Layer button (top-right).
3. Fill in the Define New Layer dialog:
   • Layer Name — A descriptive name (e.g., "Street Lights", "Water Pipes").
   • Geometry Type — Choose one from the dropdown:
     • Point (pins, assets, trees) — For discrete single-location features.
     • Line (pipes, roads, cables) — For continuous linear features.
     • Polygon (areas, parcels, zones) — For enclosed boundaries.
   • Marker Color — Select from the curated palette (11 colors), or tap the + ring to pick any custom color using the color wheel.
   • Polygon Fill Color (Polygon type only) — Choose an internal area color. Toggle the Hollow checkbox to make the polygon transparent (outline only).
   • Marker Icon (Point type only) — Tap to open the Icon Picker with searchable categories: Location, Nature, Infrastructure, Transport, Emergency, Buildings, and more.
4. Tap Create Layer.

The new layer appears in the Layer Manager with its geometry type, style preview, and form status.

Example: A fiber survey project might use three layers: "Splice Enclosures" as points, "Fiber Routes" as lines, and "Service Areas" as polygons. Keeping these themes separate makes forms, styling, and exports easier to manage.

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2. Layer Card Interface

Each layer card displays:

Element	Description
Layer Name	Tap to select this layer and jump to the Map View for drawing
Geometry Badge	Shows Point, LineString, or Polygon
Form Badge	Green ✅ Form if a form is attached; amber ⚠️ No Form if not
Symbology Preview	Visual swatch showing current marker/line/polygon style
Visibility Toggle	Show or hide the layer on the map
Zoom to Layer	Move the map to the layer's feature extent
Style	Open the Edit Layer Style modal
Schema	Open the Data Dictionary modal
Delete	Remove the layer and all its features after confirmation

Reference Layers

Reference layers are imported background polygons used for spatial auto-fill. They support visibility toggling and deletion, but they are not drawing layers.

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3. Editing Visual Styles

1. Tap the 🎨 Style button on any layer card.
2. The Edit Layer Style modal opens with these options:

Marker / Line Color

Select from the palette or use a custom color via the + ring.

Polygon Fill Color

(Polygon layers only) Set an internal area color, or check Hollow for a transparent outline.

Marker Icon

(Point layers only) Tap to open the searchable Icon Picker. Browse categories like Nature (trees, water), Infrastructure (power, construction), Buildings, Transportation, and Hazards.

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4. Completion Indicator

The Completion Indicator toggle is inside the Edit Layer Style modal.

When enabled, the map engine evaluates every feature against its attached form schema. Features where all required form fields are filled turn green on the map. Features with missing required data keep their original color.

Example: A supervisor enables the Completion Indicator on a hydrant inspection layer. Hydrants with complete required fields turn green; hydrants missing a required inspection value remain in the layer's normal color.

How to Enable

1. Open the Edit Layer Style modal.
2. Scroll to Completion Indicator.
3. Toggle the switch: "Turn features green when all form fields are filled."
4. Tap Save Style.

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5. Text Labels on the Map

Display selected attribute values directly on the map so users do not need to tap every feature to identify it.

How to Enable

1. Open the Edit Layer Style modal.
2. Scroll to Show Feature Labels.
3. Toggle the switch on.
4. A Label Field dropdown appears. Select which attribute to render (e.g., Shelter_Name, Road_ID). Choose Auto-detect to let the engine pick the best field.
5. Tap Save Style.

Example: On an inspection map, labeling the Asset_ID field lets reviewers identify hydrants, poles, or valves without opening each feature popup.

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6. Field-Based Symbology (Classification)

Classification styles features by attribute values. Instead of showing a layer in one color, Mapplex reads a selected field and applies colors based on the configured rules.

Selecting a Classification Field

1. In the Edit Layer Style modal, scroll to Field-Based Symbology.
2. Open the Color by Field dropdown.
3. Select a property from your layer's schema (e.g., Zoning_Type, Pressure_PSI).

Choosing a Symbology Type

A toggle switch appears with two options:

Categorical (Qualitative)

Best for text/string properties. The system scans all unique values and generates a color rule for each:

• Residential → Yellow
• Commercial → Red
• Industrial → Purple

You can manually add rules with the + Add Rule button and customize each rule's value and color.

Graduated (Quantitative)

Best for numeric data. Configure:

Setting	Options
Method	Quantile (equal feature count per bin), Equal Interval (consistent numeric steps), Natural Breaks / Jenks (clusters around natural data gaps)
Classes	Number of bins (2–10)
Color Ramp	Blues, Reds, Greens, Yellow-Orange-Red (Heat), Red-Yellow-Green (Diverging)

Tap Generate Bins to auto-compute the classification rules.

Hide Unclassified

Toggle Hide Unclassified to remove features from the map that don't match any classification rule. Useful for cleaning up noise when you only care about specific categories.

Example: A water utility uses Graduated classification on Flow_Rate_PSI:

• Red = low pressure
• Yellow = expected range
• Green = high or acceptable pressure

This helps reviewers spot pressure issues without opening each record.

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7. Data Dictionary (Schema)

The Schema button on each layer card opens the Data Dictionary modal. Use it to document what each field means so filters, reports, and Geova AI queries are easier to interpret.

For each field in your layer's schema, you can configure:

Setting	Purpose
Alias	Human-readable name for the field (e.g., field_abc123 → "Tree Height")
Unit	Measurement unit (e.g., "meters", "PSI", "hectares")
Role	Semantic category: Name, Category, Population, Area, Capacity, Date, Status, Slope, Amount, Identifier, Code, Notes
Type Hint	Data type override: Auto, Text, Number, Date, Category, Yes/No

A Readiness Score at the top shows what percentage of fields have been configured, such as "8/12 fields configured - 67%". Technical fields like fid, objectid, and sys_ prefixes are automatically excluded.

Why does this matter? Imported files often use short or unclear field names such as field_x47 or ht_m. The Data Dictionary lets you record that the field means "Tree Height" and uses meters, which improves filtering, reporting, and AI-assisted queries.

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8. Example: Annual Fire Hydrant Inspections

Need: A municipal water department needs to inspect hydrants and make sure each record includes a flow-rate reading.

Solution using Mapplex Layers:

1. Create the Layer: A Point layer named "Hydrants 2026" — points are ideal for exact curb locations.

2. Style the Baseline: Open Style, select a water-related icon, and set the marker color to gray.

3. Enable Labels: Toggle on Show Feature Labels and target the Cross_Street field. The map shows labels such as "Main & 5th" over each point.

4. Track Completion: Mark "Flow Rate (PSI)" as required in the form and enable the Completion Indicator. Points remain gray until required values are entered.

5. Review Results: Switch symbology to Graduated, target Flow_Rate_PSI, select a red-yellow-green ramp, and generate bins. Low-pressure points stand out for follow-up review.

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Next: Proceed to Module 03: Map View to start drawing, measuring, and collecting data on the map.