Add a reference layer

You end up with a read-only layer drawn beneath respondents’ answers, styled and labelled, visible on exactly the sections you choose.

Before you start

• A GeoJSON file in WGS 84 (longitude/latitude, EPSG:4326). Files in a projected coordinate system are rejected with a message about the coordinate system; reproject in your GIS first.
• Limits: 10 MB per file, 5,000 features per layer, 10 layers per survey. If the file is bigger, simplify or split it; see Layer too large.
• You must be an owner of the survey to manage layers.

Steps

Upload the layer

1. Open Survey settings and scroll to the Reference layers card.
2. Drop the file on the upload zone, or click it to choose the file. The card now shows the layer with its feature count and size.
3. Give it a Name respondents will understand, such as Study area or Proposed crossings.
4. Under Style, set the Colour, Opacity, Line width and, for point layers, Point size and Point icon. If the file already carries simplestyle properties (stroke, fill, marker-color and so on), those win over the layer colour.
5. To colour features by one of their properties, switch on Style by attribute, pick the Property and a Mode: Categories for a text property (one class per value) or Graduated for a number (Colour from → to across Classes with quantile, equal-interval or manual Breaks). Auto-fill from data creates the classes for you; Add class adds one by hand. Tick Show legend to respondents so the panel explains the colours.
6. Under Label field, pick the property whose value is written on each feature; leave it on none for no labels. Key field names the property that makes each feature addressable; most reference layers can leave it on none.
7. Switch on Info popups if respondents may click a feature to read its name and description. Leave it off for a pure backdrop; either way the layer never intercepts a tap meant to place an answer.

Show it on a section

A layer is on a section’s map because a question of that section shows it. Repeat for each section that needs the layer:

1. Select the section and click New Question.
2. Under Map questions, choose Objects on the map.
3. Under Layer, pick the uploaded layer. (Upload new… here uploads a file without going back to settings.)
4. Under In the panel, choose how the layer appears beside the map: a list respondents can browse and search, or a legend line with only the name, colour and a toggle. The legend line is right for a backdrop such as boundaries.
5. Click Create. Add no sub-questions if the layer is only for context; without them the question collects nothing and is a display block.

A layer can be shown once per section; a second question picking the same layer is refused with the name of the question that already shows it.

Result

The Live preview renders the layer beneath the map’s answer geometry with your styling and labels. Respondents see it on every section that has an Objects on the map question for it, can switch it off in the map’s layers control, and cannot select, move or edit its features. The Reference layers card lists the sections each layer is on. A layer that no question uses stays in the library and is shown nowhere.

To ask respondents about each feature in the layer (thumbs up or down, a comment, a rating), add sub-questions to the Objects on the map question; see Question types.

Related

• Layer too large
• Survey settings
• Add a map question