I remember the days
When I installed a very early computerised digitising system at the Ordnance Survey in Southampton. My first job was at Laser-Scan (founded by Otto Frisch). It must have been about 1980 or 1981. There was a "Fastrak" laser scanner attached to a VAX 11-780.
Here's a scan of a photo of the later design of the operator's console. A map was photographed onto a A6 negative, which was then scanned, a square mm at a time, by a red laser, and straight lines were followed automatically. The operator could select which line to follow at junctions using a tracker ball and 16 buttons (which could also be pressed as chords!). When a line had been digitised, a blue laser wrote on a piece of photochromic film sandwiched against the negative, removing it from the display.
I can remember scanning 1:1250 maps (NZ2741NW, Prebend's Bend, Durham, which was our standard demo), contour lines, and a project for the Forestry Commission where we digitised the boundaries of all the woodland in the UK (the green overlay from 1:50000 sheets, all 204 of them).
There's more history at my ex-colleague Paul's page