Interactive Data Visualisation for Animating Urban Tree Growth

Abstract

Given a set of global (natural) tree parameters measured for many specimens of different ages for a range of species, we have developed a tool that visualizes these parameters over time. The parameters include measures of tree dimensions such as heights, diameters, and crown shape, and measures of costs and benefits for growing the tree. We visualize the tree dimensions by animating tree growth over time, while the accumulated costs and benefits are visualized using animated bar charts. As our vizualisation system is targeted towards application for city planning purposes, the tree growth animation should produce trees of an appearance close to nature while being on conformation with the measured parameters. We have developed a system for single-stemmed trees that creates branching structures for different species, where the local bifurcation and elongation parameters are derived from the globally measured parameters. In addition to the measured data, we use biological knowledge to model general tree growth and to adjust to specific species. We have implemented several computationally fast methods to improve the natural growth and appearance of the trees, where the main task was to keep the tree growth modelling and the tree rendering interactive. Thus, the user can interact with the 3D visualization system during the tree growth modelling and rendering process. We have applied our visualization techniques to the growth and the temporal costs/benefits changes of nine single-stemmed tree species.