Drag the image straight onto the canvas — a photo, a scan, a screenshot of a PDF — or use Import image… in the Underlay (trace image) section of the properties panel, which appears when nothing is selected. Then calibrate the scale against one distance you know, and draw over it. The underlay is screen-only and is never printed.
Tracing is free. If you would rather not do it yourself, there is a done-for-you tracing service from €29 a floor.
Dropping a file on the editor
The canvas accepts two kinds of file:
- An image (photo, scan or screenshot of a blueprint) becomes the underlay for the current floor.
- A
.gridsnap.jsonplan opens in its own tab, replacing nothing you have open.
The type is worked out from both the file type and its extension, so a screenshot saved with an odd name still lands as an image.
Calibrating the scale
This is the step that makes the trace measurable, and it takes ten seconds:
- Click Calibrate scale… in the underlay section.
- Click two points on the image whose real distance you know — a stated dimension, a door width, a known wall.
- Type that distance.
The image is resized so that everything you trace off it comes out in real millimetres. Without this the drawing is a picture, not a plan.
Positioning the image
| Field | What it does |
|---|---|
| Opacity | How strongly the image shows through. |
| Centre X / Centre Y | Move the image under the drawing. |
| Width | Scale it by hand, if you would rather not calibrate. |
| Rotation | Square up a scan or a photo that was taken at an angle. |
Trace mode
Tick See through walls while tracing. It fades what you have drawn so the image shows through it — which is how you find the doors and windows once the walls are traced over the top of them. It is a view setting: it changes nothing in the document and nothing in the export.
What this doesn’t do
- No automatic vectorisation. Gridsnap does not convert the image to walls for you — you draw over it. That is what the tracing service is for.
- The underlay never prints. It is not on the PDF, the DXF or the PNG.
- One image per floor. Trace each storey from its own scan.
Next
Drawing a wall and drawing to an exact length — with the scale calibrated, the numbers you type and the numbers you trace agree.