Establishing what has already been scanned

In facilities that have been scanned over many years, coverage is partial and its extent is usually unrecorded. Establishing what already exists, and where, is the work that precedes any decision about further capture.

The case in front of us is an underground research facility with decades of experimental history. An internal estimate puts laser-scan coverage at somewhere between half and four fifths of the site. That figure is unaudited and is stated here as an estimate; the coverage number is itself one of the things an inventory would settle.

The partial coverage is the gap. Where scans exist, questions about geometry, clearance and change over time can be answered from the record. Where they do not, the same questions return to the people who remember. The boundary between those two conditions is not drawn anywhere at present, so neither the answerable nor the unanswerable questions can be identified in advance.

The preparation is an inventory, and it can begin immediately. For each dataset: who holds it, which area it covers, when it was captured, in what format and at what resolution, and whether it has been registered to a common coordinate system. The task requires access and one person with an overview. It requires no equipment and no site time.

What the inventory produces is a map at data scale. Every dataset is carried at the coordinates it describes, so a question about a location returns the material for that location. Files stored without a location are retrievable only by whoever remembers their names, and that dependency grows with the archive.

Sequence. Converting existing scans into something a person can walk through, and decide inside, is measured in weeks. New capture is measured in seasons, and it is specified more precisely once the existing coverage is known. The facility's own leadership set the same order as a condition for starting: build the internal capability first, then extend the capture.

We are preparing this inventory step for one facility now. Organisations holding scans whose extent is unrecorded are in the same position, and the first pass over a single site fits in an afternoon.