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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> 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 on 25th March 2015.<\/SPAN><\/SPAN><\/P> Digital Terrain Models (DTM) are bare earth models (no trees or buildings) of the Earth<\/SPAN><\/SPAN>\u2019<\/SPAN><\/SPAN>s surface.<\/SPAN><\/SPAN><\/P> 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> <\/SPAN><\/SPAN><\/P> 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> This data shows the hillshade of the DSM.<\/SPAN><\/SPAN><\/P> This data was collected by New York University. All data formats are provided as GeoTIFF rasters. <\/SPAN><\/SPAN><\/P> 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. NYU data has a grid cell size of 1meter by 1meter. This means that each cell (pixel) represents an area of 1meter squared.<\/SPAN><\/P><\/DIV><\/DIV><\/DIV>",
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