Everything You Need to Know about LiDAR Drone

Drone LiDAR vs. photogrammetry: what's the difference

With the recent developments in drone surveying, many myths and misconceptions have emerged around drone photogrammetry and LiDAR. There are as many differences as similarities between the two technologies.

What are the advantages of using LIDAR drones?

• LiDAR technology does not require good light conditions to collect points. The sensor emits its energy so it can capture points both day and night.
• LiDAR systems are capable of offering a very high point density. For example, mid-range commercial devices are capable of generating between 300 and 1,000 points per square meter.
• Related to the above, it is capable of rebuilding fine elements such as cables and power lines.
• They are teams with very high productivity since they require less overlapping of flight lines (20%-30%). In addition, each "pass" of the drone usually covers a greater width than with the most common cameras. An easy rule of thumb is to consider the width to be twice the flight height.
• In general, each measured point generates a more precise coordinate than the equivalent with photogrammetric methods.
• Very important: The laser has a certain penetration capacity, with which it is possible to obtain digital models that can, for example, ignore the vegetation. In this case, the “number of pulses” that the sensor emits determines how many bounces it can detect in a particular direction.
• The cost of the sensors is much higher in the case of LIDAR. The most basic start at tens of thousands of euros.
• The processing of the data obtained is lighter, although it is equally specialized.
• Not all LiDAR is capable of reconstructing the visible appearance of objects, so in some cases only the uncolored point cloud is available.

Understood, but drone LIDAR also has some disadvantages...

The most obvious challenge that comes with working with LiDAR is its cost. Due to greater operational complexity (and the need for more sophisticated components and sensors), you can easily spend hundreds of thousands of dollars on a complete survey solution.

This complexity also widens your margin for error and increases the reliance on an experienced professional. With multiple sensors and information not readily available without a fair amount of processing, extracting the data you need isn't straightforward.

It is also important to keep in mind that traditional LiDAR sensors are larger than simple cameras. With the growing popularity of drone surveying, the need for a larger drone to handle a heavier payload can add to an already significant expense.

With photogrammetry, RGB reconstructions are obtained in which each pixel is assigned the color that corresponds to reality, while with LIDAR the points are monochrome (without RGB). This limitation can be removed by adopting an RGB camera to the device.

Can LiDAR technology replace photogrammetry?

It depends on the case. Drone photogrammetry remains one of the cheapest and most effective methods for aerial data collection. In any case, you should ask yourself several fundamental questions when deciding on one or another method. Let's go to clear cases:

Need to model terrain in densely forested areas? If so, LIDAR is the winner. If these wooded areas appear as patches between which there is visible ground, photogrammetry is still a viable option.

Do you need to capture a large area (thousands of hectares) and time/cost is a critical factor? A laser scanner will be more productive per day, but also more expensive to move. In our experience, it is possible to capture areas of 2000-3000 hectares with a fixed-wing drone in half a week with resolutions of 3-4 cm/pixel.

Is investment a limiting factor? If so, photogrammetry is a more competitive technology.

Do you need each point to be located with a very low margin of error or do the clouds have to be extremely dense? LIDAR is your preference. Be careful, the precision of terrestrial LIDAR is greater than that achieved by similar sensors on board a moving drone.