Blog · 11 October 2026

How to put a floor plan on a satellite map, to scale

Laying a floor plan over a satellite or aerial photo tells you where the house really sits on the block, how far it is from the fences, and whether a new deck or shed will fit. The trick is to tie the drawing to the map at known points, not to drag and stretch it by eye.

What you need

The plan. A PDF, an image (a real estate brochure works), a scanned council drawing, or a DXF.
An aerial where you can see the building. Free satellite imagery is fine for most houses. Plane-flown aerial photography is sharper where you can get it.

Pin it at corners, not by eye

Pick points you can see clearly on both the drawing and the photo: outside corners of the house, the corner of a slab or a driveway. Click the point on the drawing, then the same point on the map. Plotlay works out the scale, rotation and position from the pairs.

Two points place the drawing without distorting it: it can only move, turn and scale evenly. Use this for a drawing you trust to be square.
Three or more let Plotlay check the fit and correct a stretched scan. Each point shows how far off it lands, so a wrongly clicked corner stands out.
Spread them out. Corners at opposite ends of the building are far more accurate than two corners close together.

Use the wall, not the roof

A floor plan shows walls. A photo from above mostly shows roof, and the roof hangs past the walls by the eaves (often 450 to 600 mm on a house). Photos are also taken at a slight angle, so a roof edge can sit a metre or more sideways from the wall below it. Where you can, pin to things at ground level: a slab edge, the base of a wall, a path corner.

Check it against something you know

A fit can be precise and still wrong. Measure one thing you know independently, such as a room width from the plan's own dimensions or a tape measurement on site, and compare. If it is out by more than a few percent, a pin is on the wrong corner or the brochure plan is not to scale (many are not: they are marked "not to scale" for a reason).

When the photo itself is off

Satellite and aerial photos are not perfectly placed, and different providers disagree with each other by metres. See why satellite images don't line up for what to trust instead.

Worked example with numbers: Overlay a drawing on the aerial, where the Lincoln Memorial plan lands within 0.03 m on 8 cm imagery.