I was intrigued then, when I read a recent article in the Guardian: Green streets: which city has the most trees? about another approach to mapping how tree-filled cities were.
The two particularly interesting things? Firstly, that on Google Maps Street View data and secondly that the team at the MIT Senseable City Lab made the code open source.
The researchers at MIT (in collaboration with the switzerland rcs data World Economic Forum) developed Treepedia, which currently analyses and maps the above-ground tree cover in 27 world cities (with more promised).
Treepedia map of Sydney, showing Green View Indicator percentage
Where other approaches have used satellite mapping, the MIT researchers calculated what they term the ‘Green View Index’ (GVI) using Google Street View (GSV) panoramas.
Taking this approach meant the researchers were able to represent how people perceive their environment at street level. Their GVI uses a scale from 0-100, representing the percentage of canopy coverage at any particular location.
The team go into detail about their methodology for creating the GVI in several papers, including their most recent: Mapping the spatial distribution of shade provision of street trees in Boston using Google Street View panoramas.