Concept
About measurement accuracy
What an AerTwin measurement can be trusted for, why every figure travels with its qualifier, and what zooming in does and does not change.
In short: a measurement is only as good as the captured surface under it, and AerTwin never prints a figure without the information you need to judge it. Read the qualifier — the quality word, the base surface or the resolution — before you act on a number.
Measurements are made on the model, not on the screen
Section titled “Measurements are made on the model, not on the screen”When you click the model, AerTwin finds the point on the 3D model in the cloud. Lengths, areas and volumes are computed from those points and from the model’s surface, not from the pixels of your screen.
The captured surface resolves detail to about 2 cm. Finer features — a hairline crack, the texture of the concrete — can be seen on the model and, more sharply, in the source photographs, but cannot be measured more finely than the surface allows.
Zooming in shows more, but measures no better
Section titled “Zooming in shows more, but measures no better”Moving the view closer magnifies the picture. It does not add detail to the captured surface. Closer than 1.5 m the status line says “magnified, not sharper” for that reason. To judge fine detail, open the source photographs of the point: at close range the best photographs resolve around a millimetre per pixel.
Every figure travels with its qualifier
Section titled “Every figure travels with its qualifier”| Measurement | Its qualifier | Why |
|---|---|---|
| Missing concrete (3D defect) | A quality word: Good, Fair, Indicative or Not measurable | The result depends on how well the sound face around the damage can be fitted. The word says how far the figure may be out |
| Volume | The base surface it was measured against, and the grid it was sampled on | A volume is the gap between the surface and a base that you assume. A different base gives a different answer for the same concrete |
| Depth profile | Its resolution along the line | A departure close to the resolution is a facet of the capture, not a feature of the concrete |
| Outline taken from an AI proposal | An outline check — outline or unchecked when its shape is in doubt | A point that landed on the wrong surface makes the area and perimeter describe a shape nobody drew |
A missing-concrete figure is never shown with a ± sign. It is rounded to the digits its uncertainty supports — “60,000 cm³”, not “61,347 cm³” — and the quality word carries the rest. When the uncertainty would be more than 60% of the figure, no number is printed at all: the result is Not measurable.
Limits that are part of the design
Section titled “Limits that are part of the design”- 10 cm minimum. A volume or a 3D defect is refused for an outline less than 10 cm across. Below that, the result would describe the capture rather than the concrete.
- No plan values on a wall. Area (plan) and Perimeter (plan) are not shown for an outline on a near-vertical face, where a view from above would show only a line.
- Figures are stored, not recalculated. A saved finding keeps the figures it was measured with, and the time they were measured. Opening it later shows the same numbers.
Sizes are written in the unit that suits them, switching at one whole unit: cm, cm² and cm³ below 1 m, 1 m² and 1 m³; m, m² and m³ from there. Positions and elevations are always in metres — an elevation is a place, not a size. Every surface in AerTwin, from the panel to the PDF and the CSV, uses the same rules.