Transport Canberra and City Services maps tree canopy from aerial laser scan
Transport Canberra and City Services (TCCS) recently engaged 1Spatial to analyze and extract aerial laser scanning data to accelerate the process of establishing baseline data for Canberra’s urban tree canopy coverage.
The relationships between climate change challenges, sustainability goals and community expectations are key drivers in TCCS’s development of an urban tree planting program. Informative and current data sets are being used to inform management strategies by overlaying age, density and condition data and proposing future canopy density targets.
The establishment of current baseline data for Canberra’s urban tree canopy coverage was essential to the program. In this respect, two data sets were available: a 2010 ground-based audit of trees in streets, verge areas, open spaces and parks; and new aerial laser scanning LiDAR (Light Detection And Ranging) data for the majority of urban areas across Canberra.
With a tight timeframe of four weeks to complete the project, TCCS needed to quickly analyze and extract the LiDAR data relating to trees and combine it with the ground-based audit data. After evaluating different tools and methods, TCCS chose Safe Software’s FME application and engaged 1Spatial, a Safe Software Value Added Reseller and Platinum Partner, for their expertise in analysing and extracting LiDAR data to accelerate the process.
“We were keen to use FME because we have an existing skills base,” said Daniel Goodwin, Acting Manager, Asset & Data Integration for TCCS. “FME is more user friendly than other approaches which require more specialised expertise. It also provides full transparency into the process which makes it very good for iterative development. With other tools, we weren’t sure we could get the outcome we wanted in the available timeframe.”
A 1Spatial consultant was contracted for two weeks to identify tree-related data points in the LiDAR dataset and generalise them to create smooth representations of the tree canopy.
“Within a week, 1Spatial had a good product output, and then we ran some refinements over the next week,” said Goodwin. “We used out-of-the-box smoothing algorithms in FME to generate very compelling data for our analysis.”
When the final tree canopy data was displayed in TCCS’s Geographical Information System (GIS), with canopy coverage calculated as a percentage, the value of the LiDAR data was immediately obvious.
“The LiDAR data was crucial in determining the canopy cover,” said Goodwin. “Publicly available Web mapping tools tend to merge urban and non-urban areas and overestimate urban tree cover. When we focussed on the urban areas we have control over, we could see which suburbs and streets have less canopy cover than others and better target our tree management strategy.”
TCCS can also use the new data to facilitate implementation of the urban tree planting program and communicate with key stakeholders. An interactive Web mapping tool is currently being developed to be used by urban tree planners, designers and contractors.
“FME is a great tool for handling large volumes of aerial LiDAR data and integrating it with other geospatial datasets,” said Natalie Cooney, General Manager, 1Spatial Australia. “Although aerial laser scanning is now becoming common, relatively few people have the skills to manipulate LiDAR data, and we were delighted to be able to assist TCCS.”