LiDAR (LIght Detection And Ranging) is a method of gathering huge amounts of coordinate information from satellites, and formatting this information to make points and surfaces. More info: http://en.wikipedia.org/wiki/Lidar
OSI have used this method for measuring height data for areas of Ireland for years. Raw data is filtered for anomalous data points, like birds and vegetation, and for buildings, leaving an accurate representation of ground data for a huge variety of uses.
The files come in csv formatted text file, ie "xxx, yyy, zzz" and contain millions of points (see left). By comparing layers of this information we can quickly map huge amounts of data for a given area.
Our first package of LiDAR data consists of the Limerick City and Greater Limerick Area, 50 km2 in total, landscape only, scanned in 2008, with points at 2 metre centres.
Our second package of LiDAR data was scanned in 2012 and includes a much smaller area - just the city centre, scanned at 1 metre centres, but has been filtered into separate layers, so contains the raw data, the landscape alone, and the roofscape alone.
When you bring LiDAR information into Rhino, Rhino can process each point and generate point clouds, which look like this:
In order to process so much data we split the city into a grid. Each grid square is 275 metres x 275 metres. And orientated to Limerick's Georgian Grid.
Each file contains the layers: "Grid"; "L1-Landscape"; "L2-Landscape"; "B-Roofscape"; "B&L-Roof&Landscape".
As shown, on the left. Find each file in the Google Drive folder under:
Google Drive / LiDAR 2 / Blocks / 00.3dm ,
with the relevant grid number from above replacing the "00".