La parte superiore di un punto di triangolazione, trig punto o trig pilastro nel Regno Unito e utilizzato come un punto di riferimento soprattutto per il rilievo del Regno Unito.

• Collaboratore: Stephen Sykes / Alamy Foto Stock
• ID dell’immagine: JB1H5J
• Dimensioni dei file: 51,3 MB (3,4 MB Download compresso)
• Liberatorie: Modello - no | Proprietà - no
• Dimensioni: 5184 x 3456 px | 43,9 x 29,3 cm | 17,3 x 11,5 inches | 300dpi
• Data acquisizione: 18 ottobre 2015
• Ubicazione: England, UK, Great Britain, GB, United Kingdom.

Altre informazioni

The process of placing trig points on top of prominent hills and mountains began in 1935 to assist in the accurate retriangulation of Great Britain. The Ordnance Survey's first trig point was erected on 18 April 1936 near Cold Ashby, Northamptonshire. In low-lying or flat areas some trig points are only a few metres above sea level and one is even at -1 m (near Little Ouse, Cambridgeshire, TL61718 89787). When all the trig points were in place, it was possible, in clear weather, to see at least two other trig points from any one trig point. Careful measurements of the angles between the lines-of-sight of the other trig points then allowed the construction of a system of triangles which could then be referenced back to a single baseline to construct a highly accurate measurement system that covered the entire country.

Parole chiave associate all'immagine

• a griglia
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