Measurement results

Labels are written as the Measurement panel shows them. In AerTwin, click Explain in the panel to see the plain-language sentence under each figure.

Line and outline

Figure	Meaning
Points	How many points you have clicked so far
Length	How far along the line, point to point. Each point lies on the surface
Length (plan)	The same run seen from directly above — the map distance
Perimeter	The distance right round the outline
Perimeter (plan)	The same distance seen from directly above. Not shown on a near-vertical face
Area	The real surface area inside the outline, following the slope. A tilted face has more surface than the ground it covers
Area (plan)	The ground the outline covers, seen from directly above — its footprint. Not shown past 85° from level
Elevation (Min)	The height of the lowest point, above the survey’s zero. A position, always in metres
Elevation (Max)	The height of the highest point, above the survey’s zero
Elevation (Diff)	The height difference between the highest and the lowest point
Slope (Min)	The flattest part inside the outline
Slope (Max)	The steepest part inside the outline. Both slopes are extremes found inside the outline, not averages

Volume on ground

Measured against the base surface you choose in Against. See Volume base surfaces.

Figure	Meaning
Volume (Cut)	Material above the base — what would be dug out
Volume (Fill)	Space below the base with no material in it — what would be filled in
Volume (Net)	Cut minus fill — the material left over, or short
Base surface	The base the volume was measured against. Recorded with the finding

Cut and fill are always both reported.

Volume on a wall

When the outline is on a near-vertical face, the volume is measured square to the plane through the points you traced, and the rows say so:

Figure	Meaning
Proud of the plane	Material standing out in front of that plane
Recessed behind it	Material set back behind it — a recess, a niche, a blockout
Net (proud − recessed)	The first minus the second. Positive means it stands proud overall

Missing concrete (3D defect)

Measured against a reference that the tool fits to the sound concrete just outside the outline.

Figure	Meaning
Missing	How much concrete has gone from the face, with its quality word. See Quality words
Extra material	Surface standing out past the sound face — a patch, a repair, or a face that is not flat. Never subtracted from Missing
Deepest point	The deepest single spot in the damage, measured in from the sound face
Affected area	The damaged part only — always smaller than the outline, which is traced wide onto sound concrete
Surface roughness	How bumpy the sound concrete round the damage is. The bumpier, the less certain Missing is
Reference	Where the tool decided the sound face used to run, and how well it could tell
Sampled at	How finely the surface was read. The capture resolves to about 2 cm

Depth profile

Every figure is measured square to the straight line between your two points.

Figure	Meaning
Straight distance	Point to point, straight through the air
Surface distance	The same run measured over the concrete, into every hollow and over every bump. Always the longer
Max proud	The furthest the concrete stands out in front of the straight line
Max recessed	The furthest it sits back behind the line. Never netted against Max proud
Worst departure	The larger of the two — how far out the line goes at its worst point
RMS departure	How far the concrete sits from the line typically, over the whole run
Measured against	The straight line between your two points. Nothing is fitted or assumed
Sampled at	How closely the line was read, and the smallest thing it can tell apart
Surface resolves to	The smallest thing the capture can tell apart along this line
Joined up	Stretches the traces could not reach, drawn dashed and joined across. In none of the figures
Cut off	The feature is larger than the traces could see. The tallest and deepest figures are “at least” — a lower bound
Check the cutting plane	The two points disagree about which way the surface faces, so the slice fits neither end squarely

Outline checks

Shown on a finding’s card, and as a warning in the panels, when its outline is in doubt. A sound outline shows no mark.

Mark	Meaning
outline (on the card)	Some points of the outline landed on a surface behind the one it was drawn on. Its place and type are right; its area and perimeter are not reliable
unchecked (on the card)	Too few points to tell whether the outline is sound — an unanswered question, not a clean result

Report totals

The first page of a PDF report adds up the measurements in it:

Figure	Meaning
Total area	Every area in the report, added up
Total length	Every distance in the report, added up
Total cut, Total fill	Every cut and every fill volume, added up
Missing concrete	Every missing-concrete figure added up, with its uncertainty combined and rounded once