# Overlays and layers

> Bring shapefiles, GeoJSON, images and PDFs onto the map, and switch on reference layers - geology, radon, coal mining, historical maps and your company's own.

On **Pro**, you can bring extra map data onto the base map - your own files,
reference layers such as geology, radon and coal mining, historical mapping and
your company's own WMS layers. Each is a layer you can show, hide and fade.

<Callout type="note" title="A Pro feature">
  Overlays and layers are **Pro** features; adding overlays also needs a role that
  can edit the map.
</Callout>

## Overlays

The **Overlays** layer drapes your own data over the map:

- **Vector** - upload **GeoJSON** or **shapefile** data.
- **Raster** - upload an **image** or **PDF** to position over the map, with
  **crop**, **rotate** and transform tools.

Each overlay has its own **opacity**, **visibility** toggle and style.

Overlays are scoped to **this project** by default. From the overlay's options
menu you can make one a **configuration overlay** so it shows on every project
that uses the same configuration - these are marked with a globe on the overlay's
row.

### Positioning a raster overlay

**Unlock** a raster overlay to reveal its handles, then:

- **Move** - drag the middle of the overlay.
- **Resize** - drag a **corner** to scale it (aspect ratio is kept); hold
  **Shift** to stretch it freely. Drag an **edge** to stretch one side.
- **Rotate** - drag the rotate handle; hold **Shift** to snap to 15 degrees.

**Undo** and **redo** your changes with **Ctrl+Z** and **Ctrl+Shift+Z**, or the
undo/redo buttons on the overlay's row.

### Align with two points

For an accurate plan or drawing, you can place it by matching **two known
points** rather than dragging by eye. From the overlay's options menu (the
**...** button) choose **Align with 2 points**, then:

<Steps>
  <Step title="Pick a feature on the image">
    Click something you can identify on the overlay - a building corner, a survey
    marker, a grid intersection.
  </Step>
  <Step title="Place it on the map">
    Click where that feature actually sits on the base map.
  </Step>
  <Step title="Do it again for a second feature">
    Repeat for a second point. On the last click the overlay moves, scales and
    rotates so both features land on their targets.
  </Step>
</Steps>

The image keeps its shape (it is not skewed), so this works best with accurate,
to-scale drawings. Press **Esc** or **Cancel** to stop; **Ctrl+Z** undoes it.

## Reference layers

The **Reference Layers** panel holds published map data you can switch on over
any project. Each layer has an on/off switch and an **opacity** control, and you
can drag them to change which draws on top. The publisher is credited on the map
while a layer is on. Where the service supports it, click the map to see the
feature's details.

- **Geology and environment** - BGS bedrock, superficial and artificial ground
  geology, borehole records, hydrogeology, soil parent material, historic
  landfill, source protection zones and **radon** (the BGS Indicative Atlas of
  Radon). Click a radon square to read its potential band and what it means.
- **Coal mining** - the Mining Remediation Authority's Development High Risk
  Area, Coal Mining Reporting Area, mine entries, past and probable shallow coal
  mine workings, and surface mining.
- **Historical maps** - historical and geological base mapping beneath your
  data.

### Your company's layers

If your company uses other WMS services, they can sit in the panel too, under
**Your company's layers**, on every project. A **Super Admin** adds them in OS
under **Settings > Map layers**: paste the service's address, pick the layers you
want, and give each a title and credit. They switch on, fade and reorder like the
built-in ones.