3D Powerlines Inspection

Introduction

This publication aims at illustrating the use of 3D LiDAR technology to powerlines inspection tasks. We will see the advantages of this powerful technology and we will explain why 3D data processing is the bottleneck in this use case. Then, we will show how our solution T3D Powerlines has been successfully applied for large-scale applications in the powerlines domain.

Powerlines inspection

Electricity transmission operators need a complete inventory of their infrastructures for a better management of the network. In particular, to perform tasks such as:

Powerlines inspection is usually carried out by visual assessment:

This inspection is subjective and inaccurate because it depends on the expertise, visual accuracy and fatigue of operators.
Moreover, this inspection is slow, expensive and may be dangerous in some cases.

LiDAR technology

Recent advances in remote sensing (GPS, IMU, LiDAR) allow using vehicles for 3D mapping of large-scale infrastructures such as powerlines corridors, railways, highways, urban environments, among others.

In the case of powerlines corridors, a helicopter (or a drone) flies over electrical lines and acquire precise 3D LiDAR information about the infrastructure. This information is saved as 3D point clouds for further offline processing at the office.

Since 3D point clouds represent the actual size of objects, we can make measurements, inspections and inventories as if we were in the field. This is usually called a Digital twin. (For a short introduction about 3D point clouds, take a look at this entry in our blog.)

LiDAR-based inspection is then composed of two steps:

Terra3D proposes automated tools to overcome these issues.

LiDAR data processing

Data processing means analyzing the 3D point cloud in order to get useful information for:

This processing can be carried out manually or automatically. On the one hand, an operator can manually analyze approximately 10 km per day. On the other hand, automatic processing allows analyzing more than 150 km per day.

Let's take the example of the French electricity transmission network operated by RTE, which is composed of 105 000 km.

Note that manual processing is not appropriate for large-scale applications. Automated processing is a powerful technology, it makes possible large scale applications. Let's give some statistics about our T3D Powerlines solution:

T3D POWERLINES

T3D POWERLINES is a software suite for automated 3D point cloud processing of powerlines corridors (a complete product presentation in PDF format is available here).

This software suite offers automated solutions such as 3D point cloud classification, 3D point cloud modeling and specific applications such as advanced vegetation monitoring.

3D point cloud classification

Classification is the process of giving a semantic sense to each group of points in the 3D point cloud. For example, you may be interested in determining which points correspond to wires, which to towers, which to ground and which to vegetation.

Take a look at the following video to see how our automatic software can classify 3D point clouds in an accurate, fast and reproducible way.

3D point cloud modeling

Modeling is the process of generating a geometrical entities from a 3D point cloud. It is usually carried from a previously classified point cloud. For example, wires conductors can be modeled as 3D polylines generated from a set of 3D points classified as such. Those polylines can be obtained by fitting the precise catenary shape of cables. When geometric models are exported in a common CAD format file such as DWG, DXF or SHP, this process is often called vectorisation or digitization. Such models can be easily imported into classical CAD and GIS software.

Take a look at the following video to see how our automatic software can model 3D wires conductors in an accurate, fast and reproducible way.

Advanced vegetation monitoring

After classification and modeling, you may be interested in exploiting those results in a specific application such as vegetation monitoring. For example, we can generate alerts when a wire conductor is too close to the vegetation (we all remember the tragic 2018 camp fire in California).

In the following example, we have computed the distance from the vegetation (green points) to every element in the electrical network (wires in yellow and transmission towers in blue). When vegetation is closer than a given security distance threshold, our software generates a 3D bounding box where an intervention is needed.

As illustrated in the Figure below, our software is also able to identify individual trees in the environment. This allows a precise quantification and planning of maintenance operations.

Conclusions

3D technology presents several advantage such as:

However, there exists several drawbacks related to 3D data:

As we can see, LiDAR is a very powerful technology which can be applied for 3D mapping of large-scale infrastructures such as powerlines corridors. However, 3D data processing is the bottleneck nowadays. Ongoing advances in this domain will allow LiDAR technology to be massively applied to large-scale applications.

If you are interested in this domain or need advice on your project, do not hesitate to contact us. Terra3D proposes solutions for automatic processing of 3D data in the form of licenses of our software, SaaS, consulting and technical studies.

Aerial and UAV point cloud automated processing

Terra3D expertise has been applied to high voltage electric lines asset management. We developed software to classify automatically aerial point clouds. This classification has been then used to compute lines model. This model can then be used to check if the vegetation if far enough from the lines.

Automated PCRS (urban GIS database)

Terra3D has developed powerful automated tools for automatic urban and road point cloud analysis. These tools can be used to create GIS vector data bases. In particular it can be used to match the PCRS (which stands for Plan Corps de Rue Simplifié)

PCRS

PCRS is a norm that defines GIS vector maps for urban asset management and network planning. This norm is defined by the French government, it will be mandatory for cities to be able to provide PCRS to all network managers (eletric, water and gas) before 2026. The PCRS provides a common reference for various use cases.

Method

Terra3D developed an automated pipeline to process point cloud data acquired by mobile mapping to generate PCRS maps automatically. This pipeline consist of 2 steps:

Raw unprocessed point cloud. Here the point cloud is colored, each point holds RGB information.
Automatically classified point cloud. Each class is represented as a color.
Automatically vectorized point cloud. Vectorized classes are : curb, road marking, and walls.

DTM (Digital Terrain Modeling)

DTM stands for Digital Terrain Modeling, it consist of creating a 3D representation of a terrain surface.

Terra3D has developed automated tools for DTM generation from 3D point cloud data. Our technology work with a wide range of input data :

Example of aerial LiDAR data

Example of aerial UAV LiDAR data

Example of terrestrial laser scanning data

Example of terrestrial mobile mapping LiDAR data