Bridge heights

An elevation model of the points of the interoperable point cloud bridge class (LAS 2.0-format class 10, Bridge) of the National Land Survey’s laser scanning data from the heights of bridge decks. Bridge points are manually classified as bridges under which there is a free water flow point. The classification, and thus the bridge ster, is made only in the area of quality class I of the National Land Survey of Finland’s elevation model KM2. The data is compatible with the KM2 height model (same 2 m pixel size and alignment). The altitude system is N2000. The data is part of SYKE’s open datasets (CC BY 4.0). Purpose of use: The heights of bridge decks are needed e.g. when drawing up flow patterns. The heights can also be linked to the surveyor’s KM2 altitude model, in which case the heights of bridge decks can be obtained on the bridges instead of the height of the ground level or watercourse. This way, for example, possible bridges that have been covered by flooding can be modelled in the flood risk mapping, and the areas that have been surrounded by the flood can also be identified. For more information: https://www.maanmittauslaitos.fi/maastotiedonyllapito http://www.maanmittauslaitos.fi/kartat-ja-paikkatieto/asiantuntevalle-kayttajalle/tuotekuvaukset/laserkeilausaineisto https://www.ymparisto.fi/download/noname/%7B556AB245-39FE-4DC4-A268-90DCC839C939%7D/148798, picture 3 The production area-specific las files provided by the National Land Survey of Finland for bridge points were first changed to multipoint format using ArcGIS’s las to multipoint tool. Then the Create TIN tool was used. With Delineate TIN Data Area (maximum edge length = 5 m, method = all). The data was then converted to a filegeodatabase with TIN to Raster (environmental level = same as KM2, snap raster = KM2). The data corresponds to the situation on 15 April 2021. It now covers the whole of Finland’s Class I regions. The most recent bridge is from 19 March 2021 for new areas and 18 February 2021 for updated areas. The National Land Survey of Finland delivers las files of bridge deck heights separately from new production areas (no previous laser scanning) and up-to-date production areas. If one or more updated bridge points were found in the 1 m negative buffer zone of the utm5 map magazine (distribution used in production), updated material was used as the height of the bridge covers in the area of the map magazine. Otherwise, earlier material was used. As a result of the use of the buffer zone, it has been possible to ignore the erroneous edge points left in the wrong leaf after the line arrangement.