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Add context to your projects with freely accessible IGN point clouds (HD LiDAR)

Paul Poinet avatar
Written by Paul Poinet
Updated over a week ago

As part of the national LiDAR HD program, the IGN produces and distributes 3D mapping of the entire ground and surface of France in LiDAR data. The data distributed are in particular recalibrated point clouds, raw or classified, and 3D digital models (DEM, DSM, MNH, etc.). It is possible with free and open source tools to transform the IGN point clouds (published in .laz and Lambert 93 formats) into .las or .e57 format (readable in our 3D viewer) and into the Reference Coordinate System (RCS) corresponding to your project.
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Follow these steps to add a contextual point cloud to your project!


1. Upload your point cloud

This is the easiest step! Download the point cloud tile corresponding to the context of your project via this interface. For Switzerland, Swisstopo also provides point clouds covering the entire territory in .las format.


2. Download the open source software required for transforming your point cloud

This is where it gets tricky! To transform your point cloud, you'll need to install these two open-source software programs:

  1. Miniconda is a lightweight version of the free and open-source Anaconda distribution of the Python and R programming languages, applied to the development of data science applications.

  2. PDAL is an open-source library for processing point cloud data. It's a bit like a VLC player for point clouds ;)

Actually, we need the Anaconda Prompt to use PDAL, which will take care of the transformation. Let's go 👇
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2.1. Install Miniconda

PDAL depends on other libraries, so the easiest way is to use Miniconda (a lightweight version of Anaconda).

  1. Go to the official Miniconda download page:
    👉 https://docs.conda.io/en/latest/miniconda.html

  2. Download the Miniconda installer for Windows (64-bit, Python 3.x).

  3. Launch the installer:

    • Accept the license agreement

    • Choose "Just for me" (recommended)

    • Keep the default installation location

    • Check "Add Miniconda3 to PATH" if the option is offered

  4. Once installed, open the Anaconda Prompt (this is the window you will use instead of CMD/PowerShell for PDAL).

2.2. Create a Conda environment for PDAL

It is recommended to isolate PDAL in its own environment.

In Anaconda Prompt, copy and run the following command:

conda create -n pdal-env -c conda-forge pdal python=3.10

This does three things:

  • Create an environment called pdal-env

  • Install PDAL from the conda-forge repository (latest version)

  • Installing Python (useful if you also want to use PDAL in your Python scripts)

2.3. Activate the PDAL environment

Still in the Anaconda Prompt, before using PDAL, activate the environment by running:

conda activate pdal-env

Now, any pdal command should use this environment. (If you close the terminal, run conda activate pdal-env again when you reopen it.)

2.4. Check the installation

Run:

pdal --version pdal --drivers

If a version is displayed and a list of “readers.* / filters.* / writers.*” appears, PDAL is installed. ✅ Check that writers.las is in the list if you want to export to .las. Same for the .e57 format also supported by Catenda Hub ;)



3. Transform your point cloud

We're almost there! Just a few more steps...
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3.1. Identify the EPSG code of your Coordinate Reference System (CRS)

To transform your point cloud into PDAL, you need to know the EPSG code corresponding to the coordinate system of your IFC model. Here is a non-exhaustive list of SCRs covering metropolitan France and their respective EPSG codes.

Name

EPSG

Remarks

RGF93 / Lambert-93

2154

The standard for metropolitan France, used for IGN point clouds. Covers the entire territory.

RGF93 / Lambert CC42

3942

For the zone 1 (Corse).

RGF93 / Lambert CC43

3943

For the zone 2 (south at 44° N).

RGF93 / Lambert CC44

3944

For the zone 3 (43° N by 45° N).

RGF93 / Lambert CC45

3945

For the zone 4 (44° N by 46° N).

RGF93 / Lambert CC46

3946

For the zone 5 (45° N by 47° N).

RGF93 / Lambert CC47

3947

For the zone 6 (46° N by 48° N).

RGF93 / Lambert CC48

3948

For the zone 7 (47° N by 49° N).

RGF93 / Lambert CC49

3949

For the zone 8 (48° N by 50° N).

RGF93 / Lambert CC50

3950

For the zone 9 (nord at 49° N).

File:Departements LambertCC9Zones.svg - Wikimedia Commons


3.2. Transform your point cloud using Anaconda and PDAL

Now that we know the famous EPSG code corresponding to the SCR of our project, we can FINALLY transform our point clou
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Here is an example of a command that allows you to transform your point cloud:

pdal translate ^
 "C:\Users\USERNAME\Downloads\LHD_FXX_0766_6282_PTS_LAMB93_IGN69.copc.laz" ^
 "C:\Users\USERNAME\Downloads\LHD_FXX_0766_6282_PTS_LAMB93_IGN69.copc.las" ^
 reprojection ^
 --filters.reprojection.in_srs="EPSG:2154" ^
 --filters.reprojection.out_srs="EPSG:3943"

🤓 Let's break this command down:

  1. pdal translate is the main command for performing the transformation.

  2. "C:\Users\USERNAME\Downloads\LHD_FXX_0766_6282_PTS_LAMB93_IGN69.copc.laz" is the path to the .laz file downloaded from the IGN database.

  3. "C:\Users\USERNAME\Downloads\LHD_FXX_0766_6282_PTS_LAMB93_IGN69.copc.laz" is the path where the future .las file will be created.

  4. the reprojection command --filters.reprojection.in_srs="EPSG:2154" --filters.reprojection.out_srs="EPSG:3943" allows you to reproject the point cloud from the Lambert-93 SCR (EPSG:2154) to the CC43 SCR (3943)

Copy the command and simply replace the EPSG paths and codes in input and output. Once the command is executed, your new .las file will be generated in the location specified by the target path.
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By default, IGN point clouds are not colorized, but there are commands in PDAL to add colors based on point elevation or by using a georeferenced .tif orthophoto with the same CRS. The open source software QGIS makes it easy to generate georeferenced orthophotos.
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Here is the same command with a colorization filter referencing an orthophoto:
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pdal translate "C:\Users\USERNAME\Downloads\LHD_FXX_0766_6282_PTS_LAMB93_IGN69.copc.laz" ^
 "C:\Users\USERNAME\Downloads\LHD_FXX_0766_6282_PTS_LAMB93_IGN69.copc.las" ^
 reprojection ^
 --filters.reprojection.in_srs="EPSG:2154" ^
 --filters.reprojection.out_srs="EPSG:3943" ^
 colorization ^
 --filters.colorization.raster="C:\Users\USERNAME\Downloads\Orthophoto.tif" ^
 --filters.colorization.dimensions="Red:1,Green:2,Blue:3"

3.3. Upload your point cloud to your Catenda Hub project

Once the transformation is done (to your project's CRS, and in .las or .e57 format), all you have to do is upload your point cloud to your Catenda Hub project! If you've followed all the steps correctly, it should be perfectly aligned with your project :)
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