How Green Are the Streets?

Measuring visible greenery across Chinese city centers

Collaborative Research
Street Greenery
Urban Measurement
Research Team

Ying Long

Liu Liu

Published

Feb, 2017

NoteResearch context

Research collaboration with Ying Long · PLOS ONE · 2017

Read the paper

Measuring visible greenery

How much greenery is visible from the street? We analyzed over one million Tencent Street View images from central areas of 245 Chinese cities, using color analysis to estimate a green view index and aggregate it across streets and blocks.

Four directional street images feed a color-based greenery measure, aggregated to streets and blocks.

Measurement workflow, from directional images to street and block indicators.

Comparing cities

Seasonal imagery differences led us to restrict the comparative analysis to 131 cities. The maps distinguish average greenness from its variation within each city, revealing differences that a single citywide score can hide.

Two maps showing city averages and classifications by average and variation.

City comparisons: average green view index and within-city variation.

Reading the measure carefully

Color-based greenery estimates can include non-vegetation objects and vary with season and lighting. They describe the sampled views, rather than total vegetation coverage or measured health outcomes.

Figures 3 and 5 from Long and Liu (2017), reproduced under CC BY.