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28.1.14. Point Cloud Extraction

NEW in 3.32

Nota

These algorithms are only available if QGIS uses the PDAL library version 2.5.0 or newer.

28.1.14.1. Boundary

Exports a polygon file containing point cloud layer boundary. It may contain holes and it may be a multi-part polygon.

Fig. 28.16 Extracting high vegetation and building polygons from an input point cloud layer

Parâmetros

Basic parameters

Label	Nome	Type	Descrição
Input layer	INPUT	[point cloud]	Input point cloud layer to calculate boundary for
Resolution of cells used to calculate boundary Opcional	RESOLUTION	[number]	Resolution of cells used to calculate boundary
Minimal number of points in a cell to consider cell occupied Opcional	THRESHOLD	[number]	Minimal number of points in a cell to consider cell occupied
Boundary	OUTPUT	[vector: polygon] Default: [Save to temporary file]	Specify the point cloud file to use as output. One of: Save to a Temporary File Save to File…

Advanced parameters

Label	Nome	Type	Descrição
Filter expression Opcional	FILTER_EXPRESSION	[expression]	A PDAL expression for selecting a subset of features in the point cloud data
Cropping extent Opcional	FILTER_EXTENT	[extent]	A map extent for selecting a subset of features in the point cloud data Available methods are: Calculate from layer…: uses extent of a layer loaded in the current project Calculate from layout map…: uses extent of a layout map item in the active project Calculate from bookmark…: uses extent of a saved bookmark Use map canvas extent Draw on canvas: click and drag a rectangle delimiting the area to take into account Enter the coordinates as xmin, xmax, ymin, ymax

Resultados

Label	Nome	Type	Descrição
Boundary	OUTPUT	[vector: polygon]	Output polygon vector layer with the point cloud boundary. Currently supported format is .GPKG.

Python code

Algorithm ID: pdal:boundary

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Usando os algoritmos do processamento a partir da consola for details on how to run processing algorithms from the Python console.

28.1.14.2. Density

Exports a raster file based on the number of points within each raster cell - useful for quality checking of point cloud datasets.

Fig. 28.17 Point density (number of points per 2x2 m) as a raster

Parâmetros

Basic parameters

Label	Nome	Type	Descrição
Input layer	INPUT	[point cloud]	Input point cloud layer to export
Resolution of the density raster	RESOLUTION	[number] Default: 1.0	Cell size of the output raster
Tile size for parallel runs	TILE_SIZE	[number] Default: 1000	Size of the tiles to split the data into for parallel runs
Density	OUTPUT	[raster] Default: [Save to temporary file]	Specify the raster file to export the data to. One of: Save to a Temporary File Save to File…

Advanced parameters

Label	Nome	Type	Descrição
Filter expression Opcional	FILTER_EXPRESSION	[expression]	A PDAL expression for selecting a subset of features in the point cloud data
Cropping extent Opcional	FILTER_EXTENT	[extent]	A map extent for selecting a subset of features in the point cloud data Available methods are: Calculate from layer…: uses extent of a layer loaded in the current project Calculate from layout map…: uses extent of a layout map item in the active project Calculate from bookmark…: uses extent of a saved bookmark Use map canvas extent Draw on canvas: click and drag a rectangle delimiting the area to take into account Enter the coordinates as xmin, xmax, ymin, ymax
X origin of a tile for parallel runs Opcional	ORIGIN_X	[number]
Y origin of a tile for parallel runs Opcional	ORIGIN_Y	[number]

Resultados

Label	Nome	Type	Descrição
Density	OUTPUT	[raster]	Output raster layer with number of points within each cell. Currently supported format is .TIF.

Python code

Algorithm ID: pdal:density

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Usando os algoritmos do processamento a partir da consola for details on how to run processing algorithms from the Python console.

28.1.14.3. Filter

Extracts point from the input point cloud which match PDAL expression and/or are inside of a cropping rectangle.

Fig. 28.18 Filtering of high vegetation class from an input point cloud layer

Parâmetros

Label	Nome	Type	Descrição
Input layer	INPUT	[point cloud]	Input point cloud layer to export
Filter expression Opcional	FILTER_EXPRESSION	[expression]	A PDAL expression for selecting a subset of features in the point cloud data
Cropping extent Opcional	FILTER_EXTENT	[extent]	A map extent for selecting a subset of features in the point cloud data Available methods are: Calculate from layer…: uses extent of a layer loaded in the current project Calculate from layout map…: uses extent of a layout map item in the active project Calculate from bookmark…: uses extent of a saved bookmark Use map canvas extent Draw on canvas: click and drag a rectangle delimiting the area to take into account Enter the coordinates as xmin, xmax, ymin, ymax
Filtered	OUTPUT	[point cloud] Default: [Save to temporary file]	Specify the point cloud file to export the data to. One of: Save to a Temporary File Save to File…

Resultados

Label	Nome	Type	Descrição
Filtered	OUTPUT	[point cloud]	Output point cloud layer with the filtered features of the input point cloud layer. Currently supported formats are .LAS, .LAZ, .COPC.LAZ and .VPC.

Python code

Algorithm ID: pdal:filter

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Usando os algoritmos do processamento a partir da consola for details on how to run processing algorithms from the Python console.