Abstract Summary
Urban greenery plays a crucial role in developing sustainable cities. Commonly used metrics to assess urban greenery are the Normalized Difference Vegetation Index (NDVI) and Green View Index (GVI), derived from satellite and street view imagery. Although deemed objective metrics, they can yield inconsistent results and introduce biases. To attain a comprehensive understanding and precise mapping of urban greenery, it is imperative to scrutinize the inherent biases associated with these measurement methods. In this study, we calculate satellite-based and street view-based urban greenery based on these two approaches and examine the characteristics of the two datasets across ten cities globally. Through a systematic analysis of the statistical and spatial disparities between NDVI and GVI, our findings demonstrate significant differences in urban greenery measurements derived from these two sources. We identify eight critical factors contributing to these disparities: distance-perspective limitation, single-profile constraint, access limitation, temporal data discrepancy, proximity amplification, vegetative wall effect, multi-layer greenery concealment, and noise. We analyze the implications of these measurement disparities in two urban domains: housing price estimation and air pollution correlation. The findings underscore that the choice of measurement method significantly influences research outcomes, necessitating a nuanced approach that combines both satellite and street view measurements for comprehensive urban greenery analysis. In conclusion, our study advances the understanding of biases and disparities in urban greenery measurement, advocating for a nuanced approach that integrates both satellite and street view data as there is no “true” greenery. This research contributes to the ongoing discourse on urban greenery and inspires future studies aimed at refining measurement methodologies and enhancing the quality of urban life.
