Image-based 3D Urban Tree Modeling
2013 | Dr. Justin Morgenroth, University of Canterbury
This research project aims to develop a simple new method for producing dimensionally-accurate 3D urban tree models using a basic digital camera. The technique we will assess (SfM: Structure-from-Motion) has successfully modeled the structure of objects less complex than trees (e.g. buildings). Our research group has previously produced accurate height and diameter estimates of trees in a pilot study using the SfM technique (published in Urban Forestry & Urban Greening). This research builds on the previous work by applying the technique across a range of tree forms, sizes and species to ensure its utility is widespread and not just a tool in the researcher’s toolbox.
Current approaches to tree mensuration typically include only linear measurements (e.g. height, DBH, crown spread). 3D attributes like above-ground volume (used in calculations in iTree), are estimated using allometric equations which can introduce significant error. Our 3D modelling approach will allow above-ground volume to be directly measured, not estimated. Implications exist for inventory, tree valuation, hazard tree assessment, benefit modelling, and arboriculture education.
Our method differs from previous image-based tree measurement efforts in that it’s the first to output a 3D tree model. Because it is not cost prohibitive, it is distinguished from LiDAR-based 3D tree modeling undertaken by others.