Elevation points (use heights)

Wherever precise height information is required, high-altitude points have always been used for surveying tasks and solutions in the context of construction surveying, map production and country surveying. The high-altitude points serve in their entirety the physical realisation of the high-altitude field and thus the height component of the geodetic spatial reference within the meaning of Section 2(2) of the Hamburg Law on Surveying of 20 April 2005 in the area of the Free and Hanseatic City of Hamburg (FHH). The height values are given in the official height reference system of the German Main Height Network as normal heights in “Meter via Normal Height Zero” (NHN). Since 01.12.2016, the associated coordinate reference system (CRS) is DE_DHHN_16_NH, whose height horizon is 14-17 millimeters lower than the values of the 1992 CRS DE_DHHN_92 valid until 30.11.2016. The FHH’s high-altitude field consists of hierarchically structured high-altitude nets of the I. to IV. All right. While the first three orders serve to secure the height reference, the IV is. Order, the receiving height network, as the last compression stage with around 2,600 height fixed points the basis for all private sector surveys with official height reference. The high-altitude points are determined by the state operation Geoinformation and measurement via geometric levellings and at a point distance according to each other. The last area-based review or re-determination of the altitudes took place in 2010. If necessary, individual after-measurement takes place. The height is expressed in millimeters. Metal bolts on house facades or bridge foundations are used as permanent markings. In peripheral areas with little development, granite or concrete stones introduced into the soil can also form the basis for marking. * Important note on how to handle surveying marks: Surveying marks for marking points of the fixed altitude field may only be introduced, altered, restored or eliminated by surveying points (these are the state’s Geoinformation and Surveying and Surveying Engineers approved in Hamburg!