Parameter Overview
1. Introduction to DJI L1
The Zenmuse L1 integrates a Livox LiDAR module, a high-accuracy IMU, and a camera with a 1-inch CMOS on a 3-axis stabilized gimbal. When used with Matrice 300 RTK and DJI Terra, the L1 forms a complete solution that gives you real-time 3D data throughout the day, efficiently capturing the details of complex structures and delivering highly accurate reconstructed models.
2. Specifications
3. Key Parameters
3.1 Detection Range
This refers to the farthest measurable distance of the LiDAR. This parameter varies greatly based on the actual environmental conditions. Main influencing factors include the target's surface reflectivity, the target's shape, and ambient light interference. Manufacturers generally indicate the LiDAR's measurable distance under different illumination and reflectivity. In the case of DJI L1, its LiDAR supports a measurable range of 450 meters under 0 klx when the measured target's reflectivity is 80%, and 190 meters under 100 klx when the measured target's reflectivity is 10%.
"450 m @ 80%, 0 klx" means that, when the solar illuminance is 0 klx and the measured target's reflectivity is greater than 80% (the reflectivity of a concrete floor or a road surface is 15%-30%, and the reflectivity of a white plaster wall is 90%-99%), the maximum measurable distance is 450 m.
"190 m @ 10%, 100 klx" means that when the solar illuminance is 100 klx and the measured target's reflectivity is greater than 10% (the reflectivity of a concrete floor or a road surface is 15%-30%, and the reflectivity of a while plaster wall is 90%-99%), the maximum measurable distance is 190m.
Most LiDAR sensors on the market use diffuse reflection objects (with a reflectivity of 90%) as the testing benchmark, However, this parameter has limited practical significance. The measurable distance at a reflectivity of 10% has greater practical significance.
3.2 Point Cloud Data Rate
Point cloud data rate is also called sampling frequency or pulse frequency. It refers to the maximum number of laser beams emitted by the laser within a unit of time. Given the same conditions, a higher frequency means a higher number of measured points and a higher operating efficiency.
The L1's point cloud data rate is affected by which echo mode is used. Three echo modes are available: single-echo, dual-echo, and triple-echo mode. In single-echo or dual-echo mode, the maximum sampling frequency is 240 kHz (that is, 240,000 laser beams emitted per second). In triple-echo mode, the maximum sampling frequency is 160 kHz. Theoretically, the maximum number of points measured per second in the dual-echo or triple-echo mode is 480,000. In practice, the number of points measured in the second and third echoes are very small. The number of measured points is the highest at a sampling frequency of 240 kHz in dual-echo mode. Therefore, it is recommended to choose the dual-echo mode if you need more measured points, or choose the triple-echo mode if you need higher penetration.
3.3 Scan Mode and FOV
The L1 can produce different scan shapes in different scan modes. Please note that the shape formed by the LiDAR on the ground is determined by the laser scan mode, the flight direction and speed, and the terrain. The Livox LiDAR on DJI L1 supports non-repetitive scan mode and repetitive scan mode.
Field of View (FOV), also known as the scan angle, represents the angle covered by the LiDAR sensor, or the angle at which laser signals are emitted. The FOV of L1 varies in different scan modes.
Repetitive scan: FOV 70.4 degrees * 4.5 degrees. In this scan mode, the vertical field is narrower, but the accuracy is higher. This mode is recommended for high-accuracy surveying and mapping.
Non-repetitive scan: FOV 70.4 degrees * 77.2 degrees. In this scan mode, the vertical FOV is wider. This mode is recommended for data capturing of complex structures, such as building facades.
Note:
The effective range of L1 varies based on where the object is within the FOV. The closer to the edge of the L1's FOV, the shorter the effective range.
The closer to the center of the L1's FOV, the farther the effective range. See the figure below for details.
3.4 Beam Divergence Angle
A divergence angle, if any, of the beams from the LiDAR can produce light spots which increase in size as the distance increases.
3.5 Ranging Accuracy
Ranging Accuracy refers to the discrepancy between the LiDAR-measured distance and the actual distance. Ranging accuracy is different from system accuracy in that the former does not represent the accuracy of the final result.
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