Visor
When , draw attention (from the Latin videre , see) is in the Geodesy and some lines of metrology , the straight line of sight between two or more measurement points , respectively. When exploring this line of sight, its existence is also called this.
description
An unhindered sight is the prerequisite for an accurate distance or direction measurement . If it is restricted, for example by the leaves of trees or other nearby obstructions, measurement errors or refraction disturbances may result.
If there are high demands on terrestrial surveying, it is therefore important to investigate the visibility conditions and survey points in good time . Any side refraction caused by sunlit, heated surfaces can be reduced if you pay attention to the position of the sun or more favorable weather conditions . Similar precautions can also be taken for difficult measurements in the laboratory .
Using satellite geodesy methods , many problems - especially in difficult terrain and with heavy vegetation - can be solved more easily than in the past, because the necessary sights run steeply upwards.
Strictly speaking, a sight does not run in a straight line because light rays are slightly curved by the vertical decrease in air density . This terrestrial refraction averages one-seventh the curvature of the earth . Since Gauss , this refraction coefficient has mostly been assumed to be 0.13 of the earth's curvature. Side refraction can also occur on hot objects or in the tunnel , but this is only in the range of angular seconds .