What are the top-rated drones for aerial geological surveying?

Drones significantly enhance geological surveying by efficiently collecting various types of data in hard-to-reach areas. For instance, drones with interchangeable payloads, like DJI's M350, are ideal for LIDAR applications. Additionally, smaller and more compact drones, such as the DJI Mavic 3 Series, can create high-resolution orthomosaics or capture multispectral data.

Start by defining the data requirements. This can then enable you to select the required payload. Remember, the drone is just the platform to carry the sensors, so start with the data capture requirements, work backwards: Can the area that needs to be surveyed be broken down into smaller flights to achieve a better GSD? If so, a smaller drone and sensor can be used. Do you need highly detailed data? Then opt for a larger sensor, which will require a larger drone. As Sergey mentioned, the DJI M350 is often a popular choice as it is incredibly versatile with a wide range of payload options including LiDAR, RGB and multi/hyperspectral. It also has good endurance for a multirotor and is reasonably cost-effective.

Geologists will usually use different kind of paylods on a drone, such as high-resolution cameras, LIDAR, thermal cameras, multispectral cameras, magnetometers, ground-penetrating radars or even gamma spectrometers.

So the payload is - extra weight a drone can carry - excluding the drone weight But to enable a drone more payload high specs of motor, propeller & accordingly the battery required.

Depending on the size of the area to be surveyed, it is worth considering the type of drone to be deployed. - Fixed wing airframes often have better endurance as they are more efficient in horizonal flight, but fly faster, thus reducing the quality of data (depending on the sensor used and the settings). They also require a larger take-off and landing (TOAL) area, which would need to be considered. - A vertical take-off and landing (VTOL) airframe has the ability to take-off and land in smaller TOAL areas, but has the endurance of a fixed-wing so is a good compromise. - Multirotors are more manoeuvrable, but lack the endurance, so are best used in more complex flight environments or smaller areas.

So we have done some experiments and it was found that a battery capacity x has a similar flight time than a bit higher battery capacity (x+y). This is because higher capacity batteries have higher weight & the extra capacity is wasted on overcoming its own weight, so optimization is required.

The SenseFly eBee X fixed wing is deployed and in the air within 3 mins with a 90 minute flight time. It is able to cover vast distances beyond most multi-rotors and other similar VTOL fixed wings in a similar weight class with its hand launch function and belly landing capability reserving battery power typically consumed and supporting a superior flight time. Being 1.6kg, it also negates licensing for RePL if not flying commercially. The eBee X has a wide range of interchangeable payloads for any mission type reducing the need to invest in other drone types equipped with sensors to do the job.

Take an example of comparison between DJI Avata and DJI Avata 2, the DJI Avata 2 have lighter weight design, battery capacity is smaller, and with longer flight time. :-) anyway the avata is not for aerial surveying purpose.

Post-processing does not always need to be carried out on-board. Depending on the application, it may be possible to stream data to a ground station and let the off-board system handle the post-processing. This approach requires a strong, reliable, and robust communication link between the drone and the ground station to avoid packet loss. Such a setup can enhance efficiency and flexibility in various geological applications, and extend the range and flight time of UAS operations.

The Quantum Systems Trinity F90+ is a fixed-wing drone known for its endurance and adaptability in various terrains, including remote and hard-to-reach areas. For a survey in the Arctic tundra, I deployed the Trinity F90+. Its long flight time and robust build enabled it to cover vast, icy expanses efficiently. Despite harsh weather conditions, the drone's reliable performance ensured comprehensive data collection, critical for environmental monitoring. The DJI Inspire 2 is versatile and can handle diverse terrains due to its powerful propulsion system and advanced imaging capabilities. During a canyon survey, I used the Inspire 2 equipped with a high-resolution camera.

Features to watch out for include custom terrain model flight contouring, enabling custom elevation models to be imported for uniform and consistent GSD/Point density, and minimising the risk of exceeding your max height above terrain for deliverables quality.