基于全数字摄影测量的林分立木高度量测

Measuring heights of standing trees based on digital photogrammetry.

树高是森林资源调查中的主要测树因子之一,快速准确地量测树高具有现实意义和应用价值。该文收集了东北林业大学哈尔滨市试验林场的16张航片和相应的外方位元素,建立了一个测区,通过模型的内定向、相对定向和绝对定向构建测区的立体像对模型;在立体像对模型的基础上,利用专业的数字摄影测量平台,量测研究区域内的32棵样木的高度;同时使用超声波测高器在准同步状态下实地测量32棵样木的实际高度,并将实地测量结果与数字摄影测量结果进行对比分析。结果表明,两组数据的差异不显著,基于数字摄影测量的立木高度量测的实际精度为90.92%,使用数字摄影测量量测立木高度的方法精度较高。

Tree height is one of the main factors for forest measurement and inventory.It is of great importance to measure tree height quickly and accurately.In this study,sixteen aerial photographs and the corresponding exterior orientation elements were collected for Harbin Experimental Forest Farm of Northeast Forestry University.A survey area was established and the stereopair model was developed for the area using internal orientation,relative orientation and absolute orientation techniques.On the basis of stereopair model,heights of 32 sample trees in the area were measured using professional digital photogrammetry platform in the laboratory.Heights for the same sample trees were measured using ultrasonic hypsometer in the field quasi-synchronously.The results from these two methods were compared and analyzed statistically.Results showed no significant differences among these two sets of data.The accuracy for tree height measurement using digital photogrammetry was 90.92%.This study indicates that the use of digital photogrammetry for tree height measurement can achieve high accuracy.