数字照片在树干解析上的应用

Application of digital photogrammetry in tree stem analysis

介绍了一种利用摄影测量技术开展树干解析的新方法。通过求算横截面积,换算成理论直径及年轮宽度。此法可以提高测量精度,特别是在树干横截面不规则的情况下,可以提高准确度。选择一个基本圆满的圆盘,直接测量直径和由面积换算比较年轮宽度,二者差异平均为10%,最大达32%。由于图像上直接测量的是面积,树皮的横截面可以更加准确获得,而传统的方法无法克服这个缺点。数字照片还是储存年轮信息的理想形式,便于保存和复查。本法使用的是普通的数码照片,方便适用,是开展森林精密测量简单易行手段。

A new method for tree stem analysis by digital photogrammetry was introduced in this paper. By direct quadrature, the section area of a definite tree ring was measured, and the theoretical diameter was then derived, instead of measuring the so-called average diameter, a traditional method applied for timber volume estimation. Comparing with manual survey, the accuracy of this method was significantly improved, especially when the trunk form is irregular. In our case study, the accuracy for the measurement of ring width was 10% higher than that by singledirection measure. This method could be more accurabe for bark measurement, because the gearformed section could cause larger errors in biomass or volume estimation with conventional method. Also, digital photogrammetry could be an ideal way to archive information on disks and to use it whenever necessary.