Use Cases & Requirements for Spatial Data on the Web
The OGC/W3C Working Group Spatial Data on the Web tries to improve possibilities of working with spatial data on the worldwide web. On the 25th of October 2016 the third and probably final version of the Use Cases & Requirements has been published by W3C, in collaboration with the OGC. This document, of which Geodan’s Frans Knibbe is editor, forms the basis of other results from the working group, such as the Spatial Data on the Web Best Practices.
OGC/W3C Spatial Data on the Web Working Group
For the realisation of ideas like the Internet of Things, Big Data, Smart Environments and Smart Organisations, putting spatial data to work on the web is an essential requirement. To enable this, standards need to be improved, harmonized and clarified. This is the mission of the joint OGC/W3C Spatial Data on the Web Working Group. December 2015 saw the publication of the second public working draft of the Use Cases and Requirements. This document, of which Geodan employee Frans Knibbe is co-author, forms the foundation for further work in the group.
Dynamic Holland Shading
The National Height Model of the Netherlands (AHN) which has now been released enables the height differences in the Netherlands to be identified very precisely. Using the very latest web technologies, we have created a dynamic ‘hill-shading’ map, which depending on the time and the day, shows the position of the sun using shadows.
By releasing the National Height Model of the Netherlands (AHN), the government wants to encourage the reuse of this data. The data are measured to help to manage the water in the Netherlands. However, the accuracy and the complete coverage of this data also means that it is attractive for all sorts of other uses, such as the dynamic ‘hill-shading’ map. This enables you to see which areas receive more or less sun based on the time of the day and the day in the year.
What is it?
The Dynamic Holland Shading uses techniques that are comparable to the AHN-viewer (in Dutch). By dividing the height data into small tiles and encrypting these in a particular way, the browser is able to calculate the gradient and direction. The angle of the sun is determined based on the day and the time. Then, using Web Workers a calculation is made in the background to work out the light intensity in that location (‘shadow’).
The AHN is a very large data set which requires powerful computers to work with. By serving the data in small tiles to the browser, only the data being looked at by the user has to be processed. This enables dynamic visualisations to also be created, such as a hill-shading based on the time and date, but also dynamic classification of the height in order to properly map out small height differences.
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The National Height Model of the Netherlands as Open Data
Since the 6th of March, the National Height Model of the Netherlands (AHN) has been freely accessible to everyone as Open Data. The AHN contains very accurate height data for the whole of the Netherlands and is used by the district water boards and the Department of Waterways and Public Works for water management. By making the AHN data freely available with no conditions attached, the government is encouraging the reuse of the available data.Read more about the practical implementation
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