Mobile Terrestrial Photogrammetry for Street Tree Mapping and Measurements

John Roberts,Amr Abd-Elrahman,Gail Hansen,Shawn Landry,Benjamin Wilkinson,Ali Perez,Andrew Koeser

doi:10.3390/f10080701

John Roberts, Amr Abd-Elrahman + Show 5 more

Open Access

https://doi.org/10.3390/f10080701

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Abstract

Urban forests are often heavily populated by street trees along right-of-ways (ROW), and monitoring efforts can enhance municipal tree management. Terrestrial photogrammetric techniques have been used to measure tree biometry, but have typically used images from various angles around individual trees or forest plots to capture the entire stem while also utilizing local coordinate systems (i.e., non-georeferenced data). We proposed the mobile collection of georeferenced imagery along 100 m sections of urban roadway to create photogrammetric point cloud datasets suitable for measuring stem diameters and attaining positional x and y coordinates of street trees. In a comparison between stationary and mobile photogrammetry, diameter measurements of urban street trees (N = 88) showed a slightly lower error (RMSE = 8.02%) relative to non-mobile stem measurements (RMSE = 10.37%). Tree Y-coordinates throughout urban sites for mobile photogrammetric data showed a lower standard deviation of 1.70 m relative to 2.38 m for a handheld GPS, which was similar for X-coordinates where photogrammetry and handheld GPS coordinates showed standard deviations of 1.59 m and the handheld GPS 2.36 m, respectively—suggesting higher precision for the mobile photogrammetric models. The mobile photogrammetric system used in this study to create georeferenced models for measuring stem diameters and mapping tree positions can also be potentially expanded for more wide-scale applications related to tree inventory and monitoring of roadside infrastructure.

Highlights

Municipal forest management occurs at various scales throughout the urban landscape, but it often includes the direct management of individual trees
Given this precedent of acceptable error held by past studies on point cloud accuracy, measurements from this study compare well to previous applications of SfM photogrammetry for tree measurements (Table 1), as the root mean square error (RMSE) value for diameter at breast height (DBH) was
This research has demonstrated that close-range mobile terrestrial photogrammetry can be used for the purposes of mapping and basic tree measurements for inventory purposes

Summary

Introduction

Municipal forest management occurs at various scales throughout the urban landscape, but it often includes the direct management of individual trees. While models have been created to place a monetary value on the ecosystem services offered by urban forests [3], municipal management efforts. Urban forest managers often focus their management efforts on roadside planting areas, sites where trees may require increased levels of care to become established and grow [6,7]. This management often includes the collection of street tree inventory data as a means of establishing a baseline for future monitoring and assessment [8]

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