DJI unveiled the Zenmuse L2 LiDAR and photogrammetry payload for drone surveying, bringing valuable enhancements to mapping processes. Building upon its predecessor, the L1, released in 2020, the L2 showcases notable upgrades that significantly enhance efficiency, accuracy, and data quality. If you’re interested in comparing datasets, visit our versus blog for detailed insights or contact us and ask for data sample from the L2.
In this piece, we’ll delve into the top 10 features of the L2 and explore how they can streamline drone surveying operations.
The list includes:
- High accuracy: Render centimeter-accurate reconstructions
- Supports 5 returns for dense foliage penetration and detection of small objects
- Non-repetitive scan mode for full coverage
- 20MP 4/3 CMOS sensor for high-resolution photogrammetry
- High-accuracy IMU and no warm-up required
- Fast and efficient mapping
- Three-axis stabilized gimbal
- Compatible with DJI’s flagship enterprise drones: The M300 Series
- Seamless end-to-end surveying workflows
DJI Zenmuse L2: Key Specs At A Glance
Before we look at the L2’s features in more detail, here is an at-a-glance view of this payload’s key specifications.
|Dimensions||155 x 128 x 176 mm|
|Compatible Aircraft||M300 RTK (requires DJI RC Plus);|
|Detection Range||450m @ 50% reflectivity, 0klx;|
250m @ 10% reflectivity, 100klx
|Point Rate||Single return: max. 240,000 pts/s;|
Multiple returns: max. 1,200,000 pts/s
|System Accuracy||Horizontal: 5 cm @ 150 m; Vertical: 4 cm @ 150 m.|
Both at 150m flight altitude, flight speed 15m/s
|Real-time Point Cloud Colouring Modes||Reflectivity, Height, Distance, RGB|
|LiDAR: Maximum Returns Supported||5|
|LiDAR: Maximum Sampling Frequency||240kHz for all modes, including Penta|
|LiDAR: Scan Modes||Non-repetitive scanning pattern, Repetitive scanning pattern|
|RGB Mapping Camera: Sensor Size & Effective Pixels||4/3 inch; 20MP|
|RGB Mapping Camera: Shutter Speed||Mechanical Shutter: 2-1/2000 s;|
Electronic Shutter: 2-1/8000 s
|RGB Mapping Camera: Video Resolution||4K @ 30fps|
|Recommended Data Capture Speed||15 m/s|
Best Features Of The DJI Zenmuse L2
So, let’s delve into the L2’s best features.
1: High Accuracy
Accuracy is crucial when it comes to surveying. And the L2 is an accurate drone mapping payload.
DJI states that the L2 is able to achieve:
- Horizontal: 5cm @ 150m
- Vertical: 4 cm @ 150m
These accuracies were achieved using the following parameters:
- DJI Pilot 2’s Area Route to plan the flight route
- Repetitive scanning with the RTK in FIX status
- 150m relative flight altitude
- 15m/s flight speed
- Gimbal pitch -90°
- Each straight segment of the flight route less than 1500m
- Post-processing in DJI Terra with Optimize Point Cloud Accuracy enabled.
In identical conditions, when the Optimize Point Cloud Accuracy feature is disabled, DJI reported achieving a vertical accuracy of 4cm and a horizontal accuracy of 8cm.
Experiments carried out using the L2 yielded an absolute vertical discrepancy of 44mm (equivalent to 4.4cm) at a flight altitude of 50 meters.
2: Powerful LiDAR Scanner For Dense And Detailed Digital Assets
The L2 is an effective drone LiDAR payload, enabling the creation of data-rich digital assets.
The key features in this department are:
- Point Cloud Rate: One return = maximum 240,000 pts/s; Multiple returns = maximum 1,200,000 pts/s
- High return rate: The L2 supports up to 5 returns @ 240kHz
- Detection Range: 450m
The L2’s multi-return capability, combined with its capacity to achieve higher sampling rates with increased returns, proves exceptionally valuable for creating elevation data within densely forested areas, subsequently transforming it into a Digital Terrain Model (DTM).
For example, the provided point cloud cross-sections illustrate how the L2 effectively penetrates through the forest canopy to produce a precise representation of the terrain, especially in areas characterized by dense vegetation.
Furthermore, employing multiple returns simplifies the task of data analysts in identifying and categorizing various objects within a point cloud, such as overhead wires. The vertical cross-section below vividly demonstrates the L2’s ability to detect power cables, particularly when compared to its predecessor, the L1.
3: Non-repetitive scan mode for full coverage
Similar to its predecessor, the L1, the L2 also offers two scanning modes: a line scan mode and a non-repetitive scanning pattern.
In the non-repetitive scanning mode, the scan area within the field-of-view (FOV) expands proportionally as the integration time extends. This expansion enhances the probability of detecting objects and finer details within the FOV. Moreover, the longer the drone LiDAR sensor scans a specific area, the greater the data resolution becomes, especially in comparison to the conventional line scan method.
The FOV of both modes is as follows:
- Repetitive scanning pattern: Horizontal 70°; Vertical 4°
- Non-repetitive scanning pattern: Horizontal 70°; Vertical 75°.
The Non-Repetitive Scan Mode equips the DJI Zenmuse L2 to swiftly achieve comprehensive coverage of the target area, allowing the sensor to collect data in all directions rather than following a predefined plane.
Conversely, the Repetitive Scanning Mode, characterized by a narrower field of view, excels in gathering concentrated data, making it particularly suitable for uniform and high-precision mapping tasks.
4: 20MP 4/3 CMOS sensor for high-resolution photogrammetry
The L2 is equipped with a 4/3 CMOS RGB mapping camera boasting 20MP imagery capability and a mechanical shutter to eradicate rolling shutter blur. Additionally, it offers a high-speed burst mode with a 0.7-second shooting interval, ensuring crisper and more vivid images even in swiftly changing or dynamic scenarios.
In its most fundamental capacity, the RGB sensor serves for capturing photos and recording videos. However, it holds substantial value from a surveying standpoint.
Firstly, it supports photogrammetry, facilitating the creation of 2D maps and models. For example, at an altitude of 100 meters, it produced a 2D orthomosaic with a Ground Sampling Distance (GSD) of 2.69cm.
Secondly, the RGB camera greatly enhances LiDAR data acquisition. It delivers real-time color information during the scanning process, enabling the L2 to generate true-color point clouds and reality models, as exemplified below.
Furthermore, the L2 features Point Cloud LiveView, a functionality that allows users to confirm data capture in real-time without the need to land or wait for post-processing. This capability prevents the need for additional flights and rework.
5: High-accuracy IMU
The Inertial Measurement Unit (IMU) is responsible for monitoring a drone’s instant 3-axis acceleration and angular velocity, enabling the precise determination of the aircraft’s speed, position, and altitude angles.
Therefore, a high-precision IMU is of paramount importance for ensuring the quality of LiDAR data acquisition. Without it, your point cloud would lack structure and significance, resembling nothing more than a random assortment of data points.
The IMU affords the following accuracies:
- Yaw accuracy: Real-time 0.2°; post-processing 0.005°
- Pitch/Roll accuracy: Real-time: 0.05°, post-processing: 0.025°.
As an extra convenience, there’s no requirement for an IMU warm-up period; the IMU is ready for operation immediately upon startup. Nevertheless, it’s important to note that an IMU calibration remains a necessary step during mapping missions.
6: Fast and efficient mapping
One efficiency advantage of the L2 lies in its elimination of the need for pre-flight IMU calibration.
Furthermore, it excels in data collection speed, capable of capturing data at 15m/s, which results in a notably swifter survey of the same area in comparison to the L1, which typically operates at recommended flight speeds between 8m/s and 12m/s.
Remarkably, the L2 can cover a substantial 2.5 square kilometers in a single flight.
7: 3-axis stabilized gimbal for data gap elimination
The L2 incorporates a highly capable 3-axis stabilized gimbal.
This feature actively counteracts any unintended drone movements, including tilt, roll, and pan, ensuring dynamic stability within an impressively tight range of ±0.01°. Consequently, this precise stabilization facilitates consistent point distribution, even when operating at exceptionally high scan rates.
This, in turn, substantially mitigates the risk of data gaps, effectively lowering the expenses linked to the need for re-flying missions.
8: Compatible With DJI M300 Series
The L2 is fully compatible with both the DJI M350 RTK and DJI M300 RTK drones.
The DJI M350 RTK represents a top-tier enterprise upgrade of the M300, boasting an improved IP rating, upgraded battery system, and additional safety enhancements, including an arm lock indicator and an updated FPV camera.
The M350 RTK comes bundled with the DJI RC Plus controller, which is an enhanced enterprise controller equipped with a sizable 7-inch high-brightness screen, a runtime of up to six hours (combining internal and external batteries), and a commendable IP rating.
However, it’s important to note that when utilizing the L2 with the M300 RTK, operators must also use the DJI RC Plus, which is purchased separately, and a firmware update is required. Consequently, the L2 is not compatible with the M300 RTK’s standard controller, the Smart Controller Enterprise.
Both the M350 RTK and M300 RTK are versatile drones designed for interchangeable payload capability, permitting operators to swap out the L2 for another payload as needed.
9: IP54 For Reliable Performance
With its IP54 ingress protection rating, the L2 exhibits remarkable versatility by being able to operate in a broad range of challenging weather conditions, such as snowy, smoky, foggy, and rainy environments.
Furthermore, the L2 can adeptly capture point clouds during nighttime hours and under low-light conditions.
It’s worth noting that the L2’s IP rating aligns with the weather-resistant attributes of the M300 Series. Specifically, the M350 RTK boasts an IP55 rating, the M300 RTK holds an IP45 rating, and the DJI RC Plus is also rated at IP54, ensuring consistent protection across the entire ecosystem.
10: Seamless end-to-end surveying workflows
Benefit from a seamless end-to-end surveying workflow, utilizing the DJI ecosystem throughout.
The following features benefit the data-collection process:
- Point Cloud LiveView: Fly confidently with the real-time Point cloud LiveView and laser rangefinder.
- Fieldwork Quality: Check the on-site data collection quality to support timely decisions on recollections or rework.
- Point Cloud Library: After the operation, the 3D point cloud model can be viewed immediately in the album.
Then post-mission, the data can be processed through DJI Terra.
The L2 includes a DJI Terra license for point cloud data processing, including a pre-processing and post-processing point-cloud functions.
This software supports exporting point cloud models in the following formats:
Recent enhancements in DJI Terra, including extended support for generating Digital Elevation Models (DEM) from LiDAR point cloud reconstruction, ground classification for LiDAR data, and automated Ground Control Point (GCP) marking, contribute to a more streamlined and comprehensive workflow.
Following the processing in DJI Terra, the data can be seamlessly imported into third-party software applications like Terrasolid for additional manipulation and in-depth analysis.
The DJI L2 represents a robust, highly efficient, and exceptionally precise surveying payload.
Although its primary emphasis is on LiDAR capabilities, the inclusion of an RGB camera expands its functionality to encompass photogrammetry, imparting true color to LiDAR-generated point clouds.
As a convenient plug-and-play, all-in-one solution, the L2 is poised to enhance the workflows of established drone surveying programs, while simultaneously serving as an excellent choice for those seeking an entry-level payload.