Using street view for research

In my previous post I noted that the fact that the global deforesation map produced by Hansen et al has been placed on an interactive portal equipped with streetview and high resolution background imagery allows anyone to validate the results. One way the web portal could be enhanced would be to provide tools that allow users to digitise and classify areas on the map in order to produce their own accuracy assessments and help others to interpret the processes taking place on the ground.

Much of Mexico is covered by Google street view. Although only a small portion of any landscape is visible from the road, this does provide a unique opportunity to understand patterns taking place on the landscape.

One example is “reforestation”. Hansen’s map shows reforested pixels in blue. But what do these represent on the ground? One way to infer the process taking place is by looking at the shape of the areas. Sharply defined geometric shapes are indicative of plantation. But what is being planted. We can often find out using street view.

Take this example near Tacotalpa in Tabasco.

The area is clearly a plantation of some sort.

Street view easily lets us identify the nature of the plantation.

Itt is African oil palm

We could even get an estimate of the height of the trees and thus an estimate of age using the people in the foreground as a reference.

In contrast, I recently spent more time than I would have liked obeserving roadside vegetation around Acayucan, Veracruz as a result of actions taken by the teachers union who set up an “indefinite” road block on the motorway to Mexico city. It was clear that there was a lot of regeneration of secondary vegetation in this area.

This shows up as an irregular pattern of blue pixels.

Street view helps confirm that this the vegetation has not been planted.

A combination of pattern recognition and careful intepretation of the view from the roadside could provide quite an accurate picture of land use change in Southern Mexico. Again, this would make a great “citizen science” project.