联合摄影及斜点样方法的单株植物冠层结构参数测量(Ⅰ)：冠层三维重建

ESTIMATING GEOMETRICAL PARAMETERS OF ISOLATED TREES BY COMBINING PHOTOGRAPHY AND POINT QUADRAT METHOD(Ⅰ):THREE DIMENSIONAL RECONSTRUCTION OF CANOPY

联合摄影、三维立体体元模型及光线跟踪法开展了面向高精度总面积指数(plant area index,PAI)测量的冠层精细三维模型重建研究.研究发现,冠层背景及天气条件对冠层影像分类影响显著;相机外方位元素解算精度受控制点精度影响较大,但受控制点数目影响相对较小.合理的单位体元大小及分区大小组合对于冠层三维重建至关重要,任意单位体元大小及分区大小组合可引起冠层三维重建异常.与立体体元大小相比,分区大小对冠层三维重建影响更为显著.

A method to reconstruct a precise 3D canopy model was presented by combining photography,3D voxel model and ray tracing.Data showed that canopy background and weather condition were critical for canopy image classification.Precision of camera exterior orientation elements was affected by precision of control points,but by number of control points only slightly.Arbitrary choice of size of voxel and pixel zone introduced vital errors,reasonable and harmonious choice of such sizes was critical for construction of voxel-based canopy model.Compared to voxel size,pixel zone size was even more important for such model constructions.