Algorithm of crown volume with square grid-based method

A new algorithm of crown volume based on a square grid method was presented, which was low in cost and high in efficiency and precision, and the normal errors in manual measurement of parameters can be reduced, such as total height, crown width, crown projected area, and so on. While the traditional assessments were not sufficient to provide accurate parameters owing to the irregular crown shapes, and three-dimensional laser was too expensive and fussy to afford. A numerical analysis of the proposed algorithm was presented, along with a design procedure and experimental results. Comparison of obtained results from classical methods and three-dimensional laser measurement was made. The point cloud data were acquired by non-prism total station and a coordinate grid of canopy surface was built, and then the crown volume can be computed with a square grid-based method. Analysis of the parameters had been made with satisfactory precise and the results showed that the relative error of square grid method was 4.13% and the average accuracy was 95.75%. There was no significant difference between calculation value and actual measurement for crown volume under confidence level of 0.05. Moreover, compared to the traditional manual measurement, only one-third of time was consumed by square grid method, which costed 2% of those by three-dimensional laser scanning, therefore, the expenditure was extremely reduced and efficiency was increased.