Intended Purpose: This tree cover feature class was produced for Wellington City and Suburbs; the study area can be seen in the accompanying tree canopy cover report (http://dx.doi.org/10.26021/11224). The tree cover feature class was produced using an object-based image analysis (OBIA) approach. OBIA is a semi-automated image classification method that can be used to identify trees based on aerial photography and LiDAR data. Following the OBIA, tree canopy cover was manually refined to correct errors in the tree cover classification. Boundary adjustment for tree crowns was also undertaken at a scale of no greater than 1:2,500.

Abbreviations/Acronyms:

WCC = Wellington City Council

OBIA = object-based image analysis

Refresh Rate (Data only): Static - March 2022

Data Security: Public

Ownership: Urban Design Team, WCC

Stewardship: Corporate GIS, WCC

Custodianship: Corporate GIS, WCC

Authoritative Data Sources (Data only): LiDAR data captured for Wellington City Council by Aerial Surveys from 20 March 2019 to 14 March 2020

Summary of Data Collection (Data only):

For the purpose of the OBIA, a tree was defined as an object having vegetation-like reflectance characteristics, exceeding 3.5 m in height and having a minimum diameter of 1. 5 m. Treefeatures comprise all tree and forest types. This includes, but is not limited to, park and reserve trees, street trees, trees on private property, orchards, remnant patches of native forest, hedgerows, and trees in commercially-managed, large-scale forestry plantations.

The data on which the OBIA was performed included aerial photography and LiDAR data. Aerial photography was captured by AAM NZ Ltd. for the Wellington City Council during the summer of 2016-17. Images were acquired on 24, 27, 28 February and 5 March 2017. Imagery was supplied as 10 cm pixel resolution, 3-band (RGB) uncompressed GeoTIFF. The final spatial accuracy is ± 0.2 m at 90% confidence level. LiDAR data were captured for Wellington City Council by Aerial Surveys from 20 March 2019 to 14 March 2020. As a consequence of the range in time of acquisition for LiDAR data, the tree canopy cover assessment that was completed for this report should be considered accurate as at 20 March 2019. Both aerial imagery and LiDAR data were sourced from the LINZ Data Service and licensed by Wellington City Council, for re-use under CC BY 4.0.