Territorial LiDAR
3rd LiDAR coverage of Catalonia
With the completion of the 3rd LiDAR data coverage of Catalonia from an aerial LiDAR and photographic sensor, the ICGC completes the Territorial LiDAR.
From this data, a georeferenced point cloud has been obtained with a minimum density of 8 points/m2 and a simultaneous orthoimage of 15 cm resolution. The capture of the aerial LiDAR data to cover all of Catalonia has been carried out in 2021, 2022 and 2023.
The point cloud describes the morphology of the terrain accurately while the simultaneous orthoimage helps us to interpret it. The point cloud is classified by associating at each point the element it describes, such as the terrain, vegetation or buildings, which allows us to obtain detailed information on these elements and generate elevation models..
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Main technical characteristics
The 3rd LiDAR data coverage of Catalonia is published in sheets of 1 x 1 km, where all sheets have a minimum density of 8 points/m2, and 65% of them have a density greater than 10 points/m2.
Distribution of surveys by sheets
The distribution of the point cloud density coverages of each 1x1 km sheet can be consulted in the metadata.
The 3rd LiDAR data coverage of Catalonia comes from flights made with the LiDAR sensor during the years 2021-2022 and 2023.
Data density distribution
The data density with the flight year of each 1x1 km sheet can be consulted in the metadata.
LiDAR point clouds go through different processing phases that are published as processing progresses. Initially v3r0 is published in LAZ1.4 format which corresponds to cloud of points of the 3rd coverage that have been processed to isolate the erroneous points from the rest, the classes that contain points in v3r0 are the following:
Data processing phases
Work methodology
- What is a point cloud?
It is a set of points positioned in three-dimensional space based on the coordinates (X, Y, H) of a given reference and projection system. Each of these points has different associated characteristics that help us to get to know the territory, one of the main ones is the class, which refers to the element to which the point belongs, be it the ground, a building, the vegetation, etc.
Based on this classification we obtain an accurate three-dimensional model of the different elements of the territory. - How is the flight carried out?
LiDAR data capture for the 3rd coverage of Catalonia has been done from a dual Lidar and photographic sensor on board an aircraft. The aircraft performs the necessary flight missions to capture LiDAR data and aerial images until it covers the entire Catalan territory.
This coverage required 159 missions or flight days. - What is the resulting product and how is it worked and edited?
The data captured by the dual Lidar and photographic sensor are processed in parallel. First the trajectory of the aircraft is processed and the georeference is obtained from the GPS/INS data collected during the flight. Afterwards, the LiDAR data is worked on on the one hand to obtain the cloud of points and on the other hand the aerial images to obtain an orthoimage.
The product obtained is a georeferenced cloud of points that gives a morphological view of the territory, since each point represents an element of the terrain and is the starting point for generating different elevation models.
Featured case studies
Morphological study: elevation and surface models
Elevation models are obtained from the classified point cloud, which, depending on the classes chosen, will describe the morphology of certain elements of the territory. Thus, a Digital Surface Model (DSM) can be generated from all the classes that will describe the territory with all its elements. Or a Digital Terrain Model (DTM) can be generated using only the Terrain class that will describe the relief. Combined models can also be generated to describe the elevations of the terrain with vegetation (DTMv) or with buildings (DTMe). These elevation models have multiple uses; an example would be the use of the DTM to create maps of flood zones.
Models (DSM and DTM) and image
Vegetation study
The density of the LiDAR point cloud obtained in the 3rd coverage allows a detailed description of the morphology of the trees. Different variables that characterize the vegetation can be calculated, such as the height or the fraction of covered area. In addition, the point density achieved also allows the study of the scrubland and undergrowth areas.
Detailed description of the forest
Volumetric studies
The careful modelling of the terrain morphology obtained from LiDAR data allows us to monitor changes in the territory, especially in changing areas such as waste dumps, quarries and controlled deposits. Volumetric studies of the material supplied or extracted can be carried out from the different covers.
Volumetric calculation