Georeferenced Images

Georeferencing places a scanned document — for example a survey diagram, an old plan, or an aerial photograph — onto the map in its correct real-world position. Once georeferenced, the image displays as an overlay that you can show, hide, and fade over the map.

INFO

Georeferencing is permission-controlled. If you don't see the Georeferenced Images tab or the georeference buttons described here, your account does not have the required permission.

Where to Find It

• Georeferenced Images tab — in the right (East) panel, next to Workspaces & Layers and Bookmarks. This is where you manage which georeferenced images are shown on the map.
• Attachments dialog — georeferencing starts from a feature's attachments: image and PDF attachments have a georeference button on their card.

Georeferencing an Attachment

1. Open the Attachments dialog for the feature that holds the scanned document
2. Click the georeference button on the attachment card — the Georeference Match Points window opens with the image on the left and the map on the right
3. Link at least 3 control points: click a recognisable spot on the image, then click the same spot on the map. Each pair is numbered on both sides
4. Repeat with well-spread points for the best accuracy — clicking an existing numbered marker selects that pair; clicking the same side again repositions it
5. Click Save — the georeference job is queued and processed in the background

While placing points:

• Press Esc or right-click to cancel a half-placed point
• Select a point and press Delete (or right-click it) to remove it
• Ctrl+Z undoes the last change
• Ctrl+drag selects multiple markers to move or delete as a group

TIP

If the sheet has a printed coordinate grid, click the grid cross on the image and use the Grid Y/X button to type the printed values — no map click needed. This is often more accurate than matching by eye.

Clipping the Image

Switch the matcher to Clip mode to trim away borders, legends, or blank paper: click on the image to draw the keep area — everything outside it is hidden on the map. Double-click to close the shape, drag points to adjust, and use Undo / Clear clip to correct mistakes. A ring drawn inside another becomes a hole.

Job Status

After saving, the attachment card shows the georeference status:

• Orange — queued or processing
• Green — done; the image is available on the map
• Red — failed or needs more points; open the matcher to review

The Georef Jobs button in the Attachments dialog lists your georeference jobs. To remove a georeference (but keep the attachment), click the ungeoreference button on the card.

Showing Images on the Map

Open the Georeferenced Images tab in the East panel:

• Visible Georef Images (top) — images currently shown on the map. Use the sliders to adjust the image opacity (and the base map/feature opacity) so you can compare the image against the map underneath. Click Hide to remove one from the map, or Hide all on map to clear them all.
• Available Georef Images (bottom) — georeferenced images for the features you have selected. Click Show on Map to display one, use Search and Refresh to find others, and Edit match points to reopen the matcher and refine the result.

Each entry shows the number of control points, the warp type, and the residual (in metres) — a lower residual means a more accurate fit.