Google Street View virtual survey and in-person field surveys: an exploratory comparison of urban tree risk assessment

摘要

The Bangkok Metropolitan Area (BMA), of Thailand's capital city, has approximately 1,200 kms of main and sub streets and nearly 3,000 large trees in public places. These trees need management to prevent them from potentially falling or dropping branches and so causing injury or damage to property. Unfortunately, in the BMA, very little has been done in terms of managing the street trees, with regards to their general health and vigour, and this has led to significant damage from tree failure. In order to help prioritise the BMA's tasks, a tree risk assessment tool can be used to systematically identify the tree defects and calculate the tree risk rating. This study aimed at generating reliable data for street trees based on the Google Street View (GSV) imagery. A comparison of the GSV survey with field data indicated high levels of agreement in genus and species identification. The overall risk of stem and root could be precisely predicted using the GSV virtual surveys. Unfortunately, identifying the overall crown risk, tree defects, and sizes was difficult and the results inaccurate. In the future, advanced image capturing and processing software can improve the accuracy and precision.