Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>Photogrammetry is a remote sensing technology, i.e. the technology is not in direct contact with what is being measured. From drone, aeroplane or helicopter, photographs are taken. Multiple overlapping photographs of the ground are taken. Precise measurements from the photographs can be taken to create topography maps.</SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>This data was collected using a drone carrying a digital camera in 2020.</SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>A software package was used extract points (X,Y,Z (x & y coordinates) and z (height)) from the photographs. The data is then converted into gridded (GeoTIFF) data to create a Digital Surface Model of the earth.</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><SPAN>This data shows the hillshade of the DSM.</SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN><SPAN>This data was collected by the Geological Survey Ireland. All data formats are provided as GeoTIFF rasters. </SPAN></SPAN></P><P STYLE="margin:0 0 14 0;"><SPAN>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 0.25 meter by 0.25 meter. This means that each cell (pixel) represents an area of 0.25meters squared.</SPAN></P></DIV></DIV></DIV>
Service Item Id: 2cda28341dc944ef83ab9fa759937403
Copyright Text: Contains Irish Public Sector Data (Geological Survey Ireland) licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence