[ 02 · Method ]
A survey, day by day
Seventeen stations for the sample choir, drawn here from above. Each ring is one position of the scanner; each sweep is one full turn of its head.
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01
Walk-through and control
Before any scanning we walk the building with you and fix six to eight control points with a total station: small brass studs or survey nails, placed where no one will move them. Every later visit sets up on the same points, which is what makes movement measurable.
[ Half a day ]
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02
Stations
The scanner goes wherever it can see something new: along the aisles, under each crossing, outside on every side, up in the roof spaces. Two minutes a station at survey density. We work around services, and at night when a building can't close.
[ 1 to 4 days ]
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03
Registration
Each station sees the building from its own position. We fit the clouds together on checkerboard targets and shared surfaces, then check the fit against the control points. We don't deliver until the stations agree to within 3 mm.
[ Back at the studio ]
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04
Cleaning
A scan records everything the laser hits: visitors, pigeons, a ladder, the edge of a reflection. We remove those returns by hand, so what is left is the building.
[ 1 to 2 days ]
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05
Drawings and the note
We cut the plans and sections you asked for, draw the deviation maps, and write a short note: what we measured, what moved, what we suggest. You get the files and a call to go through them.
[ Within 10 working days ]
Questions we are asked
Do you need to close the building?
No. We plan the stations around services and visiting hours, and scan the busiest areas early in the morning or at night. Visitors who walk through a scan are removed in the cleaning step.
Do you need scaffolding?
Not for the scan itself: the scanner reaches the vault from the floor. Roof spaces need safe access, boards and lighting, which the building usually has for maintenance.
Is the laser safe for people in the building?
Yes. Our scanner's laser is Class 1, eye-safe in normal use. People can walk past it while it turns.
How close do you need to work to the stone?
We don't touch it. The scanner records surfaces from a few metres to well beyond the top of a spire. The control points are the only things we fix, and they are a few millimetres across.
How do we receive the files?
By a download link, and on a drive if you prefer. The cloud for a parish church is a few gigabytes; a cathedral choir is tens of gigabytes. The drawings and the note are small enough to email.
Can you compare with a survey someone else made?
Often, yes, if it was registered to known control points or we can find enough unchanged surfaces to fit it to. Send us what you have and we will tell you before you commission anything.