Drone LiDAR Surveying

What is LiDAR Drone Surveying?

LiDAR stands for Light Detection And Ranging; Drone LiDAR mapping is the creation of topographical surfaces using laser beams to detect changes in the surface. LiDAR uses laser beams emitted from the sensor at a very high rate; the time taken to return to the sensor is calculated, and the point of contact with the surface or object is recorded.

Can you add LiDAR to a drone?

Due to recent technological advancements and reduced sensor and chip sizes, LiDAR can be mounted onto some drones. Not all drones can carry the weight of a LiDAR sensor, but the enterprise drones that we use can carry several different models of LiDAR units. 

How is a LiDAR survey different from a drone survey?

DJI L1 for Drone LiDAR Surveying

Drone LiDAR surveying differs from Photogrammetry used in our Aerial Surveys, which cannot see bare earth where vegetation or tree canopies exist. Photogrammetry uses images stitched together and georeferenced, LiDAR user’s laser beams. Laser technology uses multiple returns to penetrate the vegetation until the hard surface is reached.

Terrestrial laser scanning has been used in construction for many years, and aerial laser scanning is somewhat newer due to the size and weight of LiDAR units. Recent technological advances have allowed smaller, lighter units to be mounted on planes and drones, allowing for high-density aerial scans.

Overgrown sites or even long grass during summer months can affect the data collected by photogrammetry, and LiDAR should be used.

There are differences in mission planning due to the requirements for LiDAR and photogrammetry; this can be the difference between survey-grade and OK results. 

LiDAR Technology

We use the DJI Zenmuse L1 LiDAR unit on our M300 drones, and with the correct planning and workflow, we can achieve survey-grade accuracy. We have spent many hours on training courses to enhance our understanding of the best practices for data capture and post-processing drone lidar survey data with this sensor.

These laser units continually collect hundreds of thousands of points per second, which make up a surface that can be turned into a point cloud for processing and analysis. The collected data is highly accurate and complemented with ground control points and survey points to improve and verify the accuracy. 

Why do I need a Drone LiDAR Survey?

Some of the main areas where LiDAR shows its worth are in areas of vegetation, even medium grass; LiDAR can penetrate through to hit the hard surface of the ground. This is due to the number of returns from the LiDAR unit before it reflects off a surface. Many drone topographical surveys need to consider grass growth during summer, which can give erroneous elevation data.

Drone LiDAR surveys are often used on overgrown greenfield sites or before requested planning permission. Construction companies and developers can leverage the benefits of this technology as part of the planning and construction process.

LiDAR mapping comes into its own when vegetation or forest canopy penetration is required. Regular drone camera sensors will only see the top of the trees or the long grass in an overgrown field, and LiDAR can penetrate through the canopy of vegetation until it hits the hard surface of the ground. 

LiDAR technology can give all sorts of data, and if the collection is done right, it can even lead to the measurement of tree trunks from the resulting point cloud.

Drone LiDAR surveys generates millions of data points, each having a georeferenced value. These values are then compared with the other data points in the set, and many calculations are derived from them. Stockpile volumetrics, distance measurements, slope length and angle,  building heights and features such as windows and doors can all be extracted from the data set. 

We use industry-leading drone lidar software as with all our processes and workflows.

How much does a LiDAR drone survey cost?

There is no simple answer to a drone lidar price, but generally, the size of the site or area to be surveyed will determine the pricing. The bigger the site, the more planning and flight time required; More data will be captured on more significant sites, meaning more ground control to be placed and recorded. More significant sites generate more extensive data sets, which take longer to process. We generally price jobs based on sizing bands. Under 50 acres, 50 – 100 acres etc. The required deliverables also determine the price.

Where is LiDAR not useful?

Drone LiDAR surveys are not suitable in all situations.

LiDAR and water do not mix due to refraction and light absorption. That is not to say that LiDAR cannot penetrate water; it can, but it requires a specific wavelength beam, not what is traditionally used for land surveying. 

LiDAR is generally not a good solution in coastal erosion monitoring. Photogrammetry also has its challenges with water due to movement in the water between images, but for coastal erosion, surveying can be achieved by monitoring the tides.  

The light spectrum is large, and many specialised sensors can perform various tasks. These may or may not fit on current drone technology but will generally require custom fitting. We can provide these services and work with you to achieve your goals.

Can you use drones for LiDAR?

Drones are being used more and more in LiDAR surveys. With the reduction in size and price of Aerial mounted LiDAR units, the benefits of speed and coverage mean that it is far more economical to use Drone LiDAR surveys. When properly planned and executed, the accuracy is on a par with on-the-ground surveys and is often more accurate due to the millions of extra data-points collected. A more granular site-plan can be generated with contour details much faster than traditional surveys to achieve the same levels of accuracy.

LiDAR data and GDPR

Drone LiDAR survey data can have a less thought of but significant advantage over photogrammetry data. 

As the sensor uses laser beams and not a camera, many GDPR concerns can be removed from the equation, making it ideal in sensitive areas.

How accurate is LiDAR drone survey?

Much of this heavily vegetated site was inaccessible due to safety and vegetation density. We used the L1 LiDAR on the M300 to survey the site. We incorporated the surveyors’ on-site points, and the drone lidar survey accuracy was within 5cm across the site. The data gathered during this survey allowed us to generate contours based on the under-canopy surface and extract boundaries and break lines. Drone LiDAR mapping is excellent for the CAD and design process where site access is restricted.

Drone Lidar Survey Slope Analysis
Lidar point-cloud by reflectivity

Contact us today and discuss your drone lidar mapping requirements with us. 

We give you the right solution for your needs.