What sensors do drones use?

Drones are usually only useful when equipped with a sensor, which captures visual or other types of information of the surrounding area. There are a wide variety of sensors that drones use depending on the goal of the mission. This page gives an overview of the different sensors, what they are used for, and how to decide between them.

DJI Phantom 4 Multispectral image 1_EPOTRONIC

RGB

RGB sensors capture photos in real colour – through the red, green and blue wavelengths, just like the camera on an everyday phone. The photos can be used as they are, or to create a 3D product, the photos, which overlap with each other, are processed using photogrammetry software. Common pixels are detected between the images and, with a little bit of magic, 3D points are created, often with georeferenced coordinates, e.g. in WGS84. Typically, millions of these points are created from projects with a few hundred photos.

LiDAR

LiDAR sensors emit laser pulses to gather information on the surrounding area. Hundreds of thousands are emitted per second, allowing a detailed reconstruction of the terrain to be captured, like with photogrammetry. This data is processed in special software together with the drone's position data in order to create a point cloud with georeferenced coordinates. Some lidar sensors are also equipped with an RGB camera so that the lidar points can be coloured in real colour.

Multispektral

Multispektralsensoren liefern von den drei Sensoren die meisten Informationen. Sie ähneln den RGB-Sensoren, erfassen jedoch Daten in mehr Wellenlängen, in der Regel 5-10, statt der üblichen 3 bei RGB. Dies ermöglicht eine gründlichere Analyse des Ziels, was besonders bei landwirtschaftlichen Anwendungen nützlich ist.

Thermography

Thermographic sensors can be used to measure the radiation intensity of thermal radiation on surfaces, allowing the surface temperature to be determined. Thermographic sensors are generally used in multi-sensor systems in tandem with RGB sensors, as the higher spatial and spectral resolution of RGB sensors makes it easier to classify and localise the thermographically recorded surfaces.

Which sensor should you use?

The three sensors described above differ widely in their technology, although the main difference is when they are suitable to be used. This depends on the application but also the conditions of the drone flight e.g. weather conditions, and operational requirements or limitations.

Multispectral

Multispectral sensors are more specialist instruments that are mainly used in agriculture and research for in-depth analysis of crops, plant health, pollution detection, water quality analysis etc. To find out more about the use of multispectral sensors read our pages on this available at the following links: Precision Agriculture, Research and Development.

LiDAR vs RGB

The more difficult decision is deciding between RGB and LiDAR sensors. After all, they do essentially create almost all the same products, just by different methods. A table highlighting some of the main differences and similarities between these sensors is shown below.

As you can see in the table the main differences, are processing speed, environmental conditions usability, data size and cost. The accuracy is hard to put a number to so these figures should be taken with a pinch of salt.

The first step of making a decision is determining which sensors will be capable of capturing the required data. E.g if wanting to capture terrain beneath vegetation, only LiDAR will be suitable. If more than one sensor are still suitable, then you can look into cost, which is dependent on the cost of the product, as well as the time to capture and process the data.

Sometimes having both types of sensors can be the best option, as project requirements change over time. With modular drones such as the M300 RTK, different sensors types can be easily swapped, allowing you to undertake your work as efficiently as possible whilst retaiing quality.

Our recommendations

Below we list our top recommendations for each of the sensor types.

Thermography

Further information

For further information on the industries and applications that can be benefitted by drones, read the pages linked below. For any further advice and information feel free to call us on +49 (0) 211 5 98929 10 or email us at info@epotronic.com.