Roppa Trig Pillar

sketchfab

A concrete triangulation pillar at the northern end of Helmsley Moor, at a place called Roppa. A common sight for walkers, most were erected on prominent hill tops in the 1930’s to act as permanent survey points during the Retriagulation of Great Britain, 1935-62. This was to update data gathered during the Principle Triagulation, 1791-1853. When built, at least two others could be seen from each trig point, creating a network of basic trigonometry accurate to 3mm across the entirety of Great Britain. Now superseded by laser and aerial surveying, some have gone missing or been obscured by vegetation. However the priciple is simple and with a theodolite and two other people anyone could replicate the results today. Really an excuse for more modelling in snowy conditions, though most had blown away by the time I got up here. A beautiful but bleak spot in the winter. 60 images processed in Metashape.