Digital stereovision system for dendrometry, georeferencing and data management

A stereovision system for the in-field estimation of trees parameters such as height and diameter is proposed. The system includes a specifically developed mobile application for the management and georeferencing of stereo images. Stereo imaging allows the measurement of the distance between two points using triangulation formulas for the extraction of three-dimensional coordinates. The methodology is structured following three phases: training using system calibration through stereovision analysis of known artificial known objects; testing using measurements of standing tree diameters and heights acquired through stereovision system, laser rangefinder (height) and tree calliper (diameter); field application testing using direct height and diameter measurements in natural and urban woods. For this last phase an Android application was developed. The results show that the error between direct measurements and those measured with both stereovision and traditional reference methods (laser rangefinder and tree calliper) were quite low: 6.8 ± 6.6% between direct and laser rangefinder height measurements; 5.8 ± 5.5% between direct and stereovision height measurements; 4.2 ± 3.0% between direct and stereovision diameter measurements. No significant difference was found between the different methods for estimating height and diameter. Around 200 images matched to stereovision acquisitions were acquired and georeferenced using the application.