Earth Observation Boosted by Artificial Intelligence

27 May, 2021 | Blog

Guillaume Leclerc, P.Eng., MSc

Geomatics Specialist

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Earth observation is performed using images captured by satellites that are equipped with optical or radar sensors and serves a variety of purposes. In the last decade, there has been a significant increase in the number of satellites that monitor the Earth’s surface. Today, nearly 2,600 satellites are orbiting the Earth, of which more than 400 are capturing images of the Earth’s surface. An astronomical quantity of data is produced daily, because many of them have a high number of sensors and a short revisit frequency. This massive data availability makes it possible to carry out studies on the temporal evolution of land use and coverage.

The massive quantity of satellite images, however, makes analysis by photo interpretation very laborious, if not impossible. Various techniques have been developed in recent years to try to automate these analysis tasks. One of the leading techniques relies on artificial intelligence (AI).

Earth observation and AI

Traditionally, the various environments on the land were interpreted or classified using photo interpreters, which produces excellent results for interpreting the land target. However, this approach requires significant analysis time and is not feasible when there is an extremely high volume of images to analyze.

For over 20 years, machine learning classification algorithms, such as SVM and Random Forest, have made it possible to automate image analysis. However, prediction accuracy can vary greatly and often does not equal the work by an experience photo interpreter.

One of the reasons for this difference is that the environments that need to be classified sometimes have a high degree of complexity. This type of algorithm has difficulty capturing patterns that can be found in the environment, because it does not necessarily consider the context in which the object evolves. Still, this approach allows an approximation of land use classes and can be used as a tool for everyday projects.

In recent years, AI has become a must in the field of Earth observation. One of the reasons for this growing popularity is the ability of convolutional neural networks (CNN) to reflect the context in which the object to be classified is located. This aspect is crucial in correctly identifying objects on land. Additionally, the flexibility of these architectures makes them interesting for classifying satellite and aerial images. Finally, it has been reported that, in some cases, the accuracy of AI predictions came close to those obtained by photo interpreters.

Wetland detection using multispectral imagery and deep learning

For just over a year, there has been an interest in identifying wetlands using multispectral satellite imagery. To do this, an approach is being developed using a deep learning CNN model. This model is trained using many annotated patches that represent the various classes of interest for classification. These patches were extracted from images captured by the Sentinel-2a and Sentinel-2b optical imagery. By feeding the model with these thumbnails, it learns to extract features that identify the various wetlands.

These neural networks behave a bit like a brain while learning. They develop the ability to recognize an object after seeing it repeatedly. Eventually, a satellite image covering a region of interest that the trained algorithm has never “seen” can be provided, and the algorithm will predict a class for each of the pixels. A map is then obtained detailing the various wetlands, if any. Such a tool, while it does not replace the work of biologists in the field, provides real support for work planning.

Other AI algorithm applications

BBA has been moving toward Industry 4.0. for several years now. Using AI has become indispensable in meeting our needs and those of our clients. This is why BBA’s Geomatics team is focusing its efforts on developing innovative solutions using the latest technologies.

In addition to identifying wetlands, image classification using deep learning can be applied to many other situations. BBA has expertise in the fields of mining, electricity and oil and gas. Deep learning can be used to analyze satellite or aerial images in an automated and recurring manner. This approach is therefore ideal to regularly monitor major projects.

A concrete example of a project would be vegetation detection on linear network rights-of-way. This technique could be used to perform regular monitoring of vegetation that may come into conflict with these networks, thereby limiting potential damage to the infrastructure. Another application would be automated object detection, such as buildings or electricity pylons in a given area.

Naturally, the potential of deep learning is not limited to these tasks. Satellite imagery provides a phenomenal amount of land information over a long period of time. Infrastructure monitoring will certainly become more efficient and faster when this wealth of data is combined with machine learning.

The BBA team has experience in this area and can offer advice on the best approach to take. Contact us to discuss your projects!

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