Digital Terrain Model, AHN
In the Netherlands detailed height data is freely available as open data. This dataset is called ‘Actueel Hoogte Bestand Nederland’ (AHN). Height data is essential for the Ministry of public works, waterbodies and provinces in the Netherlands for water management and flood defense works. Height data is needed to determine the water capacity of rivers, floodplains and land. In addition height data supports maintenance and preservation processes. Detailed height information is also of interest to local governments, enterprises and researches. Archeologists are able to detect new forgotten historic settlements based on small height differences in the AHN data which can’t be seen normally.
AHN2, AHN3 and other height data
The Dutch AHN program is developed by a partnership of the Ministry of public works, waterbodies and provinces in the Netherlands. In the 1997-2003 period the first edition, AHN1, was acquired with a full coverage of the Netherlands. In the 2007-2012 period the second edition, AHN2, was acquired and September 2015 was the starting data of the third edition that will be completed in 2019.
On the 6th of March 2014 the decision was made to publish AHN as open data. Since then AHN is freely available as raw point clouds and as aggregated raster datasets. AHN consists of many LIDAR surveys combined into one dataset that is split into many tiles. These tiles are distributed via two public websites www.pdok.nl and www.nationaalgeoregister.nl. Although the level of detail is very high there are organizations with a need for more detail. These organizations conduct additional height surveys and want to combine their own datasets with AHN.
A configured AHN datasource is available for GeolinQ users to import AHN2 and AHN3 tiles from PDOK. Raw point clouds as well as aggregated raster datasets are supported. The GeolinQ AHN datasources offers an ISO 19115 based metadata schema to store the metadata of imported tiles. Configured color scales are available to visualize and interpret AHN datasets and to publish these datasets as web services for further distribution. The datasource can easily be changed or extended by end-users to add custom metadata definitions for their own height data surveys .
More information concerning the AHN datasource (in Dutch) can be found via AHN tutorial on GeolinQ support.