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Scenario Parameters

Scenario Parameters let you define interactive controls — sliders, toggles, and color pickers — that adjust layer properties in real time. When you move a slider, the bound layer updates instantly on the map without you having to open the style editor.

Parameters are useful for planning exploration: for example, a "Building Height" slider can extrude a polygon layer from 0 to 200 metres, letting you and your stakeholders test different massing options within a single scenario.

Parameters are stored as part of the scenario snapshot, so each scenario can have its own independent set of controls.

Parameter types​

TypeControlUse for
NumberSlider with min, max, and stepHeight, opacity, stroke width, point size, marker scale
ToggleOn/off switchShow or hide a layer (Visibility)
ColorColor pickerFill color, stroke color

What can a parameter control?​

Each parameter is bound to one property on one layer. The available properties depend on the layer type and geometry:

All layer types:

  • Opacity
  • Visibility

GeoJSON polygon layers:

  • Extrusion height
  • Fill color
  • Stroke color

GeoJSON line layers:

  • Stroke color
  • Stroke width

GeoJSON point layers:

  • Fill color
  • Point size
  • Marker scale
note

Only one parameter can be bound to any given layer property at a time. If a binding is already in use, the form will show a validation error.

Creating parameters​

Open the Scenarios panel and click the settings icon (or the Configure Parameters button) on the active scenario. This opens the Scenario Parameters manager.

You can add up to 10 parameters per scenario.

Add a parameter manually​

  1. Click Add Parameter.
  2. Enter a Name for the parameter (for example, "Building Height"). Names must be unique within the scenario.
  3. Select a Layer from the dropdown — all layers in the project are listed.
  4. Select a Property to bind to. The list updates based on the layer type and geometry.
  5. The form auto-fills sensible defaults (min, max, step, default value, unit) based on the property you chose. Adjust them if needed.
  6. For number parameters, optionally enter a Unit label (for example, m, floors, %) that appears next to the slider.
  7. Click Save Parameters.
tip

When you select a property, the parameter name is automatically suggested from the layer name and property — for example, "Proposed Buildings Extrusion height". You can overwrite this at any time.

Auto-Detect​

Auto-Detect scans all currently visible layers and suggests parameters for every bindable property not already parameterized.

  1. Click Auto-Detect in the Parameter Manager.
  2. Review the list of suggested parameters. Extrusion height suggestions for polygon layers are pre-selected — they tend to be the most useful.
  3. Tick or untick individual suggestions.
  4. Click Add Parameters to add the selected ones in one step.
note

Auto-Detect only scans visible layers. If a layer is toggled off, make it visible first and then run Auto-Detect again.

Editing and removing parameters​

In the Parameter Manager list, each parameter shows:

  • Its name
  • The layer and property it is bound to
  • The min–max range and unit (for number parameters)

Click the pencil icon to edit a parameter, or the trash icon to delete it. Deleting a parameter is immediate and cannot be undone.

Using parameters in the viewer​

When the active scenario has one or more parameters, the What If Parameters panel appears automatically at the bottom-centre of the map.

  • Sliders — drag left or right to change a number value. The layer updates as you drag.
  • Toggles — click to switch a boolean property on or off.
  • Color pickers — click the color swatch to open a picker and choose a new color.
  • Reset to defaults — click the reset button (top-right of the panel) to return all parameters to their configured default values.

The panel appears when you switch to a scenario that has parameters and disappears automatically when you switch to a scenario without them.

Parameters work in publicly shared scenarios. When someone opens a shared link, the What If Parameters panel is shown with the same controls, along with a short guide: "Adjust parameters to explore different planning options."

Public viewers can move sliders and change colors exactly as in the main app. Their changes are local to their browser session — they do not affect the saved scenario or other viewers.

This makes parameters a powerful tool for public engagement: you can publish a shared link and let residents or decision-makers explore planning options themselves without needing an account.

See Sharing for how to create and manage shared links.

GeoAI integration​

The GeoAI Agent can adjust parameters on your behalf using the adjustScenarioParameter tool. You can ask it things like:

  • "Set the building height parameter to 45 metres"
  • "Turn off the visibility parameter for the green space layer"
  • "Change the fill color parameter to red"

The agent applies the value immediately to the live map, just as if you had moved the slider yourself.

Limits​

  • Maximum 10 parameters per scenario.
  • Each parameter can bind to only one layer property. You cannot have two parameters controlling the same property on the same layer.
  • Parameter values are reset to their defaults when you switch away from a scenario and back again, because the scenario snapshot stores the parameter definitions, not the current slider position of the user's session.