Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>LiDAR (Light Detection and Ranging) is a remote sensing technology, i.e. the technology is not in direct contact with what is being measured. From satellite, aeroplane or helicopter, a LiDAR system sends a light pulse to the ground. This pulse hits the ground and returns back to a sensor on the system. The time is recorded to measure how long it takes for this light to return. Knowing this time measurement scientists are able to create topography maps.</SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>LiDAR data are collected as points (X,Y,Z (x & y coordinates) and z (height)). The data is then converted into gridded (GeoTIFF) data to create a Digital Terrain Model and Digital Surface Model of the earth. This LiDAR data was collected between June and October 2018.</SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>Digital Terrain Models (DTM) are bare earth models (no trees or buildings) of the Earth</SPAN></SPAN><SPAN><SPAN>’</SPAN></SPAN><SPAN><SPAN>s surface.</SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>Digital Surface Models (DSM) are earth models in its current state. For example, a DSM includes elevations from buildings, tree canopy, electrical power lines and other features.</SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>Hillshading is a method which gives a 3D appearance to the terrain. It shows the shape of hills and mountains using shading (levels of grey) on a map, by the use of graded shadows that would be cast by high ground if light was shining from a chosen direction.</SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN>This data shows the hillshade of the DTM.</SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN>This data was collected by BlueSky and GeoAeroSpace and provided to the Geological Survey Ireland. All data formats are provided as GeoTIFF rasters but are at different resolutions. Data resolution is 1m.</SPAN></P><P><SPAN>Both a DTM and DSM are raster data. Raster data is another name for gridded data. Raster data stores information in pixels (grid cells). Each raster grid makes up a matrix of cells (or pixels) organised into rows and columns. This data has a grid cell size of 1 meter by 1 meter. This means that each cell (pixel) represents an area of 1 meter squared.</SPAN></P></DIV></DIV></DIV>
Service Item Id: aa216ec5ac0d472282083bed3329bc17
Copyright Text: Contains Irish Public Sector Data (Geological Survey Ireland) licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence