Individual Tree Detection in Large-Scale Urban Environments using High-Resolution Multispectral Imagery

TL;DR

This paper presents a deep learning approach for detecting individual trees in large-scale urban environments using high-resolution multispectral imagery, enabling comprehensive urban forest mapping and analysis.

Contribution

A novel convolutional neural network method for large-scale urban tree detection using multispectral imagery, with extensive evaluation across multiple cities and climate zones.

Findings

Achieved 73.6% precision and 73.3% recall in California.

Mapped approximately 43.5 million urban trees in California.

Demonstrated scalability of deep learning for urban forestry studies.

Abstract

We introduce a novel deep learning method for detection of individual trees in urban environments using high-resolution multispectral aerial imagery. We use a convolutional neural network to regress a confidence map indicating the locations of individual trees, which are localized using a peak finding algorithm. Our method provides complete spatial coverage by detecting trees in both public and private spaces, and can scale to very large areas. We performed a thorough evaluation of our method, supported by a new dataset of over 1,500 images and almost 100,000 tree annotations, covering eight cities, six climate zones, and three image capture years. We trained our model on data from Southern California, and achieved a precision of 73.6% and recall of 73.3% using test data from this region. We generally observed similar precision and slightly lower recall when extrapolating to other California climate zones and image capture dates. We used our method to produce a map of trees in the entire urban forest of California, and estimated the total number of urban trees in California to be about 43.5 million. Our study indicates the potential for deep learning methods to support future urban forestry studies at unprecedented scales.