LiDAR guide · an IPR project
Glossary
- LiDAR
- Distance measured by laser pulses fired from an aircraft. Each return is a point with coordinates and height.
- Point cloud
- All the measured points, each classified (ground, vegetation, building, water).
- LAZ
- Compressed form of LAS, the usual format for LiDAR point clouds.
- DTM (MDT)
- Digital terrain model: bare ground only, without vegetation or buildings.
- DSM (MDS)
- Digital surface model: the ground with everything on it.
- Vegetation height
- The difference between DSM and DTM. Shows the height of canopies and buildings.
- Hypsometry
- Elevation shown by colour, in height classes.
- Contour lines
- Lines joining points at the same height, at set intervals (1 m, 2 m, 5 m).
- Hillshade
- An image of the ground lit by a virtual light. Brings out fine forms: terraces, ditches, old tracks.
- Slope
- Steepness of the ground, in percent or degrees.
- Aspect
- The direction each slope faces (north, south, east, west).
- Flow accumulation
- For each cell, the upstream area draining into it. It traces the watercourses.
- Strahler order
- Hierarchy of watercourses: two of order 1 meet in one of order 2, and so on.
- VRT
- GDAL virtual raster: joins many tiles into one light file, without copying them.
- PT-TM06
- Official coordinate system of mainland Portugal, ETRS89 / PT-TM06 (EPSG:3763).
- Cascais vertical datum
- Height reference of mainland Portugal: mean sea level measured at the Cascais tide gauge.
- CC BY 4.0
- Open licence: you may use the data, commercially too, as long as you credit the source.