The Environment Agency have recently released the first delivery of their LIDAR Point Cloud dataset as open data. This release is part of the #OpenDefra project which will see 8,000 datasets being released as open data by the end of June 2016. The Environment Agency has used the data since 2005 to generate height models, mainly for flood modelling and coastal mapping.
I have spent some time exploring the LIDAR point cloud dataset, now released as open data, to see how it can be used within the ArcsGIS platform with some simple use cases. The data, which you can download from the Environment Agency’s data.gov page in grids, contains 16,600 km2 of data captured between July 2014 and November 2015. Once downloaded, the data can be decompressed using tools such as laszip.exe to create a LAS dataset, to use with ArcMap or ArcGIS Pro.
I started off by exploring the data in its rawest form within a 3D scene in ArcGIS Pro. Below shows the complexity and magnitude of the point cloud dataset, which can be interrogated and analysed further using tools such the 3D sample tools and ArcGIS 3D Analysts.
The raw LAS dataset contains height classifications so you can change how the dataset is visualised by using the out-of-the-box LAS filters / LAS Properties tools within ArcMap or ArcGIS Pro. You can use the predefined settings, as well as classifications to change what is shown from the dataset.
The filters also mean you can create digital elevation models. For example using the ‘LAS Dataset to Raster’ conversion tool when all the filters are turned off, you can create a digital surface model (DSM), shown below. Additionally by setting the LAS filter to ground, you can create a digital terrain model (DTM). These elevation models can then be used in a variety of ways.
The first scenario I looked at is using the LIDAR data to extract tree cover. I used a similar methodology the one in the Keeping Rivers Cool Manual by the Environment Agency. I stated that trees were any feature > 2.5m which were not within 2m of a building.
Using this methodology, some geoprocessing tools and the OS Open Map - Local dataset, I created a raster dataset that contains vegetation above 2.5 meters with all OS Open buildings excluded. Below is an example of the raster dataset overlaid onto areal imagery. As you can see it has quite clearly picked out the tree canopies. This dataset has a variety of purposes, for example; estimating tree cover in an area, canopies intersecting electricity pylons and riparian vegetarian growth.
The second scenario I looked at is creating 3D buildings using the LIDAR data. By using the OS Open Map – Local buildings dataset, which is free to download, you can use ArcGIS Pro to create a 3D building scene as shown in the image below. These were created by converting the raster DSM layer to a polygon vector, then using a spatial join to attach the height Z value to the OS Open buildings. Within ArcGIS Pro a 3D scene can then be created by extruding the buildings using the Z values gained from the LIDAR data.
Again this type of dataset will have many uses such as: scenario planning, situational awareness and estimating property view sheds. This is a quick and simple way to create a free 3D dataset, all done out-of-the-box with ArcGIS Pro.
I hope this post has given you an idea about how you can use the newly released point cloud dataset from the within the ArcGIS Platform. Why not give it a go yourself and find other ways which the dataset could be used within the platform.