基于无人机遥感的绿化园林三维绿量估算与分析——以福州大学校区为例

三维绿量能够从立体空间上描述城市绿地的空间分布和定量评价城市绿化的环境效益。本文以福州大学为研究区，探讨了利用可见光无人机影像估算绿化树木三维绿量的方法，并对校园生态效益进行定量分析。首先获取高于10cm分辨率的无人机可见光遥感影像；其次结合可见光波段的光谱特征与无人机数据点云的高程特征获得研究区的冠层高度模型；然后通过局部最大值算法与标记控制分水岭算法提取单木树高、株数以及冠径参数，通过野外实测数据构建“树高-冠高”关系模型得到冠高；最后结合树种分布情况，按照不同的树冠形状构建三维绿量估算模型，并基于三维绿量估算校园不同树种的生态效益。结果表明：研究区内三维绿量总量达到了804405m3，其中休闲区的三维绿量总量为428566m3，占总绿量的53.3%，而科技园区的三维绿量总量为26568m3，仅占总绿量的3.3%；而常见树种中，三维绿量贡献最大的为榕树，达到404405m3，占三维绿量总量的50.3%，而丹桂贡献的三维绿量仅为509m3，占总绿量的0.063%。研究认为：基于无人机遥感数据，能够较好的估算出研究区内绿化树木的三维绿量。

Estimation and analysis of three-dimensional green volume in green gardens based on UAV remote sensing--A case study of Fuzhou university campus

Three-dimensional green volume can describe the spatial distribution of urban green space and quantitatively evaluate the environmental benefits of urban green space. Taking Fuzhou university as the research area, this paper discussed the method of estimating the three-dimensional green volume of trees by visible light UAV image, and made a quantitative analysis on the ecological benefits of campus. Firstly, the visible remote sensing image of UAV with a resolution higher than 10cm was obtained. Secondly, the canopy height model of the study area was obtained by combining the spectral characteristics of visible bands with the elevation characteristics of UAV data point cloud. Then, the local maximum algorithm and marker controlled watershed algorithm were used to extract the tree height, plant number and crown diameter parameters, and the "tree height - crown height" relationship model was constructed based on field measured data to obtain the crown height. Finally, based on the distribution of tree species, the estimation model of three-dimensional green volume was built according to different tree canopy shapes, and the ecological benefits of different tree species on campus were estimated based on the three-dimensional green volume. The results show that the total amount of three-dimensional green volume in the study area reached 804405m3, of which the total amount of three-dimensional green volume in the leisure area was 428566m3, accounting for 53.3% of the total green amount, while the total three-dimensional green volume in the science and technology park was 26568m3, accounting for only 3.3% of the total green volume. Among the common tree species, the largest contribution of three-dimensional green volume is banyan tree, which reaches 404405m3, accounting for 50.3% of the total three-dimensional green volume, while the contribution of osmanthus is only 509m3, accounting for 0.063% of the total green volume. According to the research, based on the remote sensing data of UAV, the 3d green volume of trees in the study area can be estimated well.