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{{Short description|Vertical datum used in Germany}}
{{italic title}}
{{italic title}}
[[File:Vertical references in Europe.svg|thumb|320px|Map of vertical reference areas in Europe. {{Farblegende|#EEDD88|Area covered by the NHN datum}}]]
[[File:NHN 2008 Harz 6076.JPG|thumb|right|NHN height sign in the [[Harz mountains]] of Germany on the Brocken road]]
[[File:NHN 2008 Harz 6076.JPG|thumb|right|NHN height sign in the [[Harz mountains]] of Germany on the Brocken road]]


'''''{{lang|de|Normalhöhennull}}''''' ("standard elevation zero") or '''NHN''' is a [[vertical datum]] used in Germany.
'''''{{lang|de|Normalhöhennull}}''''' ({{IPA|de|nɔʁmaːlˈhøːənˌnʊl}}, "standard elevation zero") or '''NHN''' is a [[vertical datum]] used in Germany.


In geographical terms, NHN is the [[plane of reference|reference plane]] for the [[normal height]] of a topographical eminence [[height above mean sea level]] used in the 1992 German Mean Height Reference System (''{{lang|de|Deutsches Haupthöhennetz}}'').<ref>[http://www.bkg.bund.de/nn_159884/EN/FederalOffice/Geodesy/RefSys/NatRefHeight/EN__Height02__node.html__nnn=true ''The German Height Reference System''] at www.bkg.bund.de. Retrieved on 14 Feb 2010.</ref> The plane is in the shape of a quasi-[[geoid]]. The reference height is a [[geodesy|geodetic]], fixed point on the New Church of St. Alexander at [[Wallenhorst]] in the German state of [[Lower Saxony]]. The [[geopotential height]] of this point was calculated in 1986 as part of the United European Levelling Network (UELN), based on the [[Amsterdam Ordnance Datum]], which represents the average level of the [[North Sea]].
In geographical terms, NHN is the [[plane of reference|reference plane]] for the [[normal height]] of a topographical eminence [[height above mean sea level]] used in the 1932 German Mean Height Reference System (''{{lang|de|Deutsches Haupthöhennetz}}'').<ref>[http://www.bkg.bund.de/nn_159884/EN/FederalOffice/Geodesy/RefSys/NatRefHeight/EN__Height02__node.html__nnn=true ''The German Height Reference System''] at www.bkg.bund.de. Retrieved on 14 February 2010.</ref> The plane is in the shape of a quasi-[[geoid]]. The reference height is a [[geodesy|geodetic]], fixed point on the New Church of St. Alexander at [[Wallenhorst]] in the German state of [[Lower Saxony]]. The [[geopotential height]] of this point was calculated in 1986 as part of the United European Levelling Network (UELN), based on the [[Amsterdam Ordnance Datum]].


== Definition ==
== Definition ==
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== Change-over from NN to NHN ==
== Change-over from NN to NHN ==
Since 1 January 2000 the whole of Germany has changed its height system over to [[normal height]]s based on the [[datum (geodesy)|datum]] of the [[Amsterdam Ordnance Datum]], known as the German Mean Height Reference System, DHHN92. At the same time the new NHN is the basis of the United European Levelling Net (UELN), formerly known as the ''{{lang|fr|Reseau Européen Unifié de Nivellement}}'' or {{lang|fr|REUN}}, which standardises the height systems of the European countries. Heights in this system are given in '''metres above NHN''' or '''m (NHN)'''.
Since 1 January 2000 the whole of Germany has changed its height system over to [[normal height]]s based on the [[datum (geodesy)|datum]] of the [[Amsterdam Ordnance Datum]], known as the German Mean Height Reference System, DHHN92. At the same time, the new NHN is the basis of the United European Levelling Net (UELN), formerly known as the ''{{lang|fr|Reseau Européen Unifié de Nivellement}}'' or {{lang|fr|REUN}}, which standardises the height systems of the European countries. Heights in this system are given in ''' meters above NHN''' or '''m (NHN)'''.


The NHN was introduced because for heights above {{lang|de|[[Normalnull]]}} the actual [[earth's gravity|gravitational field of the earth]] was not taken into account. As a result, there were changes in both the old West German [[geodesy|normal orthometric heights]] (new methods of calculation) and the normal heights of East Germany (with respect to the Amsterdam Datum). The elevations differed — depending on location — by 0.06 to 0.16 metres. As a result of new measurements as part of the changeover, however, variations of 0.59 metres ({{lang|de|[[Zugspitze]]}}) have surfaced.<ref name="LVG_3-2009">{{cite web | url=http://www.vermessung.bayern.de/file/pdf/2063/kundeninformation_09_03.pdf |title=Kundeninformationn 3/2009 |publisher=[[Landesamt für Vermessung und Geoinformation Bayern]] |pages=2 |date=September 2009|access-date=2013-04-25 |language=German | format=pdf}}</ref>
The NHN was introduced because for heights above {{lang|de|[[Normalnull]]}} the actual [[Earth's gravity|gravitational field of the Earth]] was not taken into account. As a result, there were changes in both the old West German [[geodesy|normal orthometric heights]] (new methods of calculation) and the normal heights of East Germany (with respect to the Amsterdam Datum). The elevations differed — depending on location — by 0.06 to 0.16 m. As a result of new measurements as part of the changeover, however, variations of 0.59 m ({{lang|de|[[Zugspitze]]}}) have surfaced.<ref name="LVG_3-2009">{{cite web | url=http://www.vermessung.bayern.de/file/pdf/2063/kundeninformation_09_03.pdf |title=Kundeninformationn 3/2009 |publisher=[[Landesamt für Vermessung und Geoinformation Bayern]] |pages=2 |date=September 2009|access-date=2013-04-25 |language=German }}</ref>


Older [[cartographic relief depiction|relief map]]s often show heights above the old reference planes. Current maps by the federal survey authorities are based on NHN.<ref>Response by the [[Bundesamt für Kartographie und Geodäsie|Federal Office for Cartography and Geodesy]] of 13 November 2012 to this specific question.</ref> At the beginning of 2013 most of the federal states (except Berlin, Thuringia and Saxony-Anhalt) had complete coverage by the new digital topographic mapping at 1:25,000 scale (DTK). Not all the maps have appeared in print yet.<ref>[http://www.geodatenzentrum.de/isoinfo/Iso_Prod_Ueber.iso_ueber_produkt?prodid=11&iso_spr_id=1&iso_spr_web=1 geodatenzentrum.de] {{webarchive|url=https://web.archive.org/web/20131029221636/http://www.geodatenzentrum.de/isoinfo/Iso_Prod_Ueber.iso_ueber_produkt?prodid=11&iso_spr_id=1&iso_spr_web=1 |date=2013-10-29 }}</ref> On the DTK25 maps, NHN is used for elevations, however, on the DTK25-V scanned topographic maps {{lang|de|[[Höhennull#SNN56|Höhennull]]}} (HN) and {{lang|de|[[Normalnull]]}} (NN) are still being used.<ref>[http://www.adv-online.de/icc/extdeu/binarywriterservlet?imgUid=3ab60d30-b338-9eff-de33-50376a112976&uBasVariant=11111111-1111-1111-1111-111111111111 adv-online.de]</ref>
Older [[cartographic relief depiction|relief map]]s often show heights above the old reference planes. Current maps by the federal survey authorities are based on NHN.<ref>Response by the [[Bundesamt für Kartographie und Geodäsie|Federal Office for Cartography and Geodesy]] of 13 November 2012 to this specific question.</ref> At the beginning of 2013 most of the federal states (except Berlin, Thuringia and Saxony-Anhalt) had complete coverage by the new digital topographic mapping at 1:25,000 scale (DTK). Not all the maps have appeared in print yet.<ref>[http://www.geodatenzentrum.de/isoinfo/Iso_Prod_Ueber.iso_ueber_produkt?prodid=11&iso_spr_id=1&iso_spr_web=1 geodatenzentrum.de] {{webarchive|url=https://web.archive.org/web/20131029221636/http://www.geodatenzentrum.de/isoinfo/Iso_Prod_Ueber.iso_ueber_produkt?prodid=11&iso_spr_id=1&iso_spr_web=1 |date=2013-10-29 }}</ref> On the DTK25 maps, NHN is used for elevations; however, on the DTK25-V scanned topographic maps {{lang|de|[[Höhennull#SNN56|Höhennull]]}} (HN) and {{lang|de|[[Normalnull]]}} (NN) are still being used.<ref>[http://www.adv-online.de/icc/extdeu/binarywriterservlet?imgUid=3ab60d30-b338-9eff-de33-50376a112976&uBasVariant=11111111-1111-1111-1111-111111111111 adv-online.de]</ref>


== Old East German height system ==
== Old East German height system ==
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== External links ==
== External links ==
* [http://www.crs-geo.eu/nn_124396/crseu/EN/CRS__Description/crs-national__node.html?__nnn=true Description of NHN system] {{en icon}}
* [http://www.crs-geo.eu/nn_124396/crseu/EN/CRS__Description/crs-national__node.html?__nnn=true Description of NHN system] {{Webarchive|url=https://web.archive.org/web/20160303183226/http://www.crs-geo.eu/nn_124396/crseu/EN/CRS__Description/crs-national__node.html?__nnn=true |date=3 March 2016 }} {{in lang|en}}
* [http://www.lverma.nrw.de/aufgaben/landesvermessung/grundlagen/dhhn92/DHHN92.htm LVA NRW: DHHN 92] {{de icon}}
* [http://www.lverma.nrw.de/aufgaben/landesvermessung/grundlagen/dhhn92/DHHN92.htm LVA NRW: DHHN 92] {{Webarchive|url=https://web.archive.org/web/20080415212927/http://www.lverma.nrw.de/aufgaben/landesvermessung/grundlagen/dhhn92/DHHN92.htm |date=15 April 2008 }} {{in lang|de}}
* [http://www.bkg.bund.de/nn_159150/DE/Bundesamt/Geodaesie/Refsys/NatRefHoehe/Hoehe__node.html__nnn=true BKG: Height reference systems] {{de icon}}
* [http://www.bkg.bund.de/nn_159150/DE/Bundesamt/Geodaesie/Refsys/NatRefHoehe/Hoehe__node.html__nnn=true BKG: Height reference systems]{{Dead link|date=February 2023 |bot=InternetArchiveBot |fix-attempted=yes }} {{in lang|de}}
{{Use dmy dates|date=March 2020}}


{{DEFAULTSORT:Normalhohennull}}
{{DEFAULTSORT:Normalhohennull}}

Latest revision as of 00:08, 23 July 2024

NHN height sign in the Harz mountains of Germany on the Brocken road

Normalhöhennull (German pronunciation: [nɔʁmaːlˈhøːənˌnʊl], "standard elevation zero") or NHN is a vertical datum used in Germany.

In geographical terms, NHN is the reference plane for the normal height of a topographical eminence height above mean sea level used in the 1932 German Mean Height Reference System (Deutsches Haupthöhennetz).[1] The plane is in the shape of a quasi-geoid. The reference height is a geodetic, fixed point on the New Church of St. Alexander at Wallenhorst in the German state of Lower Saxony. The geopotential height of this point was calculated in 1986 as part of the United European Levelling Network (UELN), based on the Amsterdam Ordnance Datum.

Definition

[edit]
The curved blue line is the quasi-geoid Normalhöhennull reference plane.
Key: Erdoberfläche - earth's surface
Normalhöhe = normal height
ellipsoidische Höhe - ellipsoidal height
Quasigeoidhöhe - quasi-geoid height.

The NHN plane is a theoretical reference plane. It is derived by deducting normal heights from the normal plumb line. The difference between the resulting quasi-geoid and the reference ellipsoid is called the height anomaly or quasi-geoid height.

Change-over from NN to NHN

[edit]

Since 1 January 2000 the whole of Germany has changed its height system over to normal heights based on the datum of the Amsterdam Ordnance Datum, known as the German Mean Height Reference System, DHHN92. At the same time, the new NHN is the basis of the United European Levelling Net (UELN), formerly known as the Reseau Européen Unifié de Nivellement or REUN, which standardises the height systems of the European countries. Heights in this system are given in meters above NHN or m (NHN).

The NHN was introduced because for heights above Normalnull the actual gravitational field of the Earth was not taken into account. As a result, there were changes in both the old West German normal orthometric heights (new methods of calculation) and the normal heights of East Germany (with respect to the Amsterdam Datum). The elevations differed — depending on location — by 0.06 to 0.16 m. As a result of new measurements as part of the changeover, however, variations of 0.59 m (Zugspitze) have surfaced.[2]

Older relief maps often show heights above the old reference planes. Current maps by the federal survey authorities are based on NHN.[3] At the beginning of 2013 most of the federal states (except Berlin, Thuringia and Saxony-Anhalt) had complete coverage by the new digital topographic mapping at 1:25,000 scale (DTK). Not all the maps have appeared in print yet.[4] On the DTK25 maps, NHN is used for elevations; however, on the DTK25-V scanned topographic maps Höhennull (HN) and Normalnull (NN) are still being used.[5]

Old East German height system

[edit]

In East Germany normal heights used to be referred to as heights above Höhennormal or HN. The 1958 Kronstadt Tide Gauge (Kronstädter Pegel) was used as the datum. The new NHN heights are typically 12–15 cm higher. The maximum deviations in the spirit level points of first order are between 7 and 16 cm.[6]

References

[edit]
  1. ^ The German Height Reference System at www.bkg.bund.de. Retrieved on 14 February 2010.
  2. ^ "Kundeninformationn 3/2009" (PDF) (in German). Landesamt für Vermessung und Geoinformation Bayern. September 2009. p. 2. Retrieved 25 April 2013.
  3. ^ Response by the Federal Office for Cartography and Geodesy of 13 November 2012 to this specific question.
  4. ^ geodatenzentrum.de Archived 2013-10-29 at the Wayback Machine
  5. ^ adv-online.de
  6. ^ "Höhenreferenzsysteme". Bundesamt für Kartographie und Geodäsie. Retrieved 8 May 2009.
[edit]

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