The principle
A photo contains geometric relationships but no absolute measurements. To convert pixels to metres, you need an anchor: a known measurement in the photo.
Reference methods
Manual reference: Click an element (e.g. the door), enter the known dimension: "height 210cm". This becomes the anchor. All other elements are calculated relative to it. If the door is 400 pixels high = 210cm, then 1 pixel = 5.25mm.
Automatic detection: The AI recognises known objects and estimates their size. Standard doors: ~210cm. Standard windows: ~120cm. Less accurate (±10%) than manual (±5%), but works when you have no measurement at hand.
Perspective correction
Nobody photographs exactly head-on. PlotonIQ corrects slight perspective distortion (up to ~15-20°) automatically by detecting parallel lines in the facade. For strong angles, take a second photo from the other side.
Accuracy by method
Manual reference + frontal: ±3-5%. Most accurate. A 150cm window is detected as 143-158cm. More than sufficient for quotes.
Auto reference + frontal: ±8-12%. Fine for preliminary estimates.
Manual reference + angled: ±7-10%. Perspective correction compensates partly.
For production — when cutting film — always measure on site. AI measurement replaces the initial survey, not the production measurement.