Toitū Te Whenua LINZ LiDAR QC Application

linz-lidar-qc is a command line application that consists of tools to aid in quality checking LiDAR data, created by Toitū Te Whenua Land Information New Zealand. Currently only works in Windows operating system.

Installation

Store code locally and install Anaconda.

In the Anaconda Terminal, navigate into the directory where the code is stored (using cd), and use the environment yml file to create a conda virtual environment:

conda env create -f environment.yml

Activate the environment:

conda activate lidar-qc

Install the application:

pip install --editable .

License

This repository is licensed under the MIT license. For more information see the license file.

Usage

The application is called using linz-lidar-qc. Use --help for more information on the application.

There are currently 5 commands on the application. More commands will be added as development continues.

build-vrt

Creates a virtual raster for a directory of tif files.

Basic usage: --input can be used more than once in command line.

linz-lidar-qc build-vrt --input H:\lidar-dataset\Raw\DEM

check-dataset

Gathers metadata information on all products of LiDAR data (raster and point clouds) and outputs information to a geopackage. This tool also checks the tiling of a dataset. Use the --build-vrt argument to build vrts for the raster folders.

Basic usage: --input assumes a file structure where all 3 product folders are within a parent directory. The script will look in the parent directory and run the script on any folder names that cotain laz/las/point/dem/dsm (capitalisation is fine). --output is the location and name for the geopackage that gets created.

linz-lidar-qc check-dataset --input H:\lidar-dataset\Raw --output H:\lidar-dataset\Processed\metadata_output.gpkg

To check product file numbers against tile-index feature number:

linz-lidar-qc check-dataset --input H:\lidar-dataset\Raw --output H:\lidar-dataset\Processed\metadata_output.gpkg --tile-index H:\lidar-dataset\Raw\tile_index.shp

To run the command on 1 child folder, use --ras-folder and/or --pc-folder:

linz-lidar-qc check-dataset --input-dir H:\lidar-dataset\Raw --output-gpkg H:\lidar-dataset\Processed\metadata_output.gpkg --ras-folder DEM --pc-folder LAZ

density-raster

Creates a density raster vrt from the point clouds, based on a point cloud filter. Use --help to see all the filter options.

Basic usage: --input is the location of the point cloud folder and --filter is how the point clouds will be filtered to create the density raster.

linz-lidar-qc density-raster --input H:\lidar-dataset\Raw\LAZ --filter ground

To run a series of pre-set density rasters, use the filter 'common'. This will create a density raster for pulse, ground, low vegetation, buildings, unclassified, and noise.

linz-lidar-qc density-raster --input H:\lidar-dataset\Raw\LAZ --filter common

psid

Creates a text file that contains a pointcloud file name and a list of the point source ID's in that file.

Basic usage: --input is the location of the point cloud folder and --output is the location where the output text file will be created.

linz-lidar-qc psid --input H:\lidar-dataset\Raw\Point_cloud --output H:\lidar-dataset\Processed

To compare point source ID's for a dataset against the flightline ID's use both --flightline and --fid-field

linz-lidar-qc psid --input H:\lidar-dataset\Raw\Point_cloud --output H:\lidar-dataset\Processed --flightline H:\lidar-dataset\Raw\flightline.shp --fid-field FLIGHT_LIN

rename

Rename DEM, DSM or Point Cloud files in accordance with section 9.2 in the New Zealand National Aerial LiDAR Base Specification. This function runs as a dry run initially until --write is passed. It renames the existing files and does not make a copy.

Basic usage: --input is the path to the directory containing subfolders of raster and point cloud files. ``--yearis the start year of the survey.--write` confirms the overwrite. `--limit` limit the amount of files the dry-run is run against.

Run a dry-run on 100 files:

linz-lidar-qc rename --input H:\lidar-dataset\Processed --year 2020 --limit 100

To rename files:

linz-lidar-qc rename --input H:\lidar-dataset\Processed --year 2020 --write