Scientists have mapped 1.8 billion individual tree canopies across millions of kilometres of the Sahel and Sahara regions of West Africa. It is the first time ever that trees have been mapped in detail over such a large area.
So how was it possible? Researchers analysed a huge database of satellite images using artificial intelligence. They employed neural networks which are able to recognise objects, like trees, based on their shapes and colours.
To train it, the AI system was shown satellite images where trees had been manually traced. This involved lead author Martin Brandt going through the arduous process of identifying and labelling nearly 90,000 trees himself, beforehand.
From these images, the computer learnt what a tree looked like and could pick out individual canopies from the thousands of images in the database. Brandt says it would have taken millions of people years to identify the trees without the AI system.
In a review of the research, commissioned by Nature, scientists at New Mexico State University wrote that “it will soon be possible, with certain limitations, to map the location and size of every tree worldwide”