The invention provides a system for accurately and quickly measuring the crown breadth of a tree by using an unmanned aerial vehicle. The system comprises an unmanned aerial vehicle, a high-altitude reference rod, a ground horizontal reference rod and a processor. A camera is carried on the unmanned aerial vehicle, the high-altitude reference rod is hung at the bottom of the unmanned aerial vehicle through a connecting rope, and the ground horizontal reference rod is arranged on the ground below a crown breadth of a tree to be measured. Using the length ratio of actual length between two points on the edge of any crown which is obtained by calculation, the length of the high-altitude reference rod and the length ratio of the length of the high-altitude reference rod in the first image or the second image to the two points on the edge of any crown, a first proportionality coefficient and a second proportionality coefficient are obtained. The crown breadth scale measured in the image isconverted into an actual crown breadth scale through the first proportionality coefficient, and the crown breadth area measured in the image is converted into an actual crown breadth area through thesecond proportionality coefficient. According to the invention, the crown breadth scale and area can be accurately and efficiently measured, the intelligence, automation and high efficiency of crown breadth measurement are improved, and the labor cost is reduced.

本公开提供了一种利用无人机准确快速测量树木冠幅的系统，包括无人机、高空参照杆、地面水平参照杆以及处理器，无人机上搭载有摄像头，高空参照杆通过连接绳挂接在无人机的底部，所述地面水平参照杆设置在待测树木冠幅下方的地面上；利用计算得到的任意树冠边缘两点间的实际长度、高空参照杆的长度以及第一图像或者第二图像中的高空参照杆的长度与任意树冠边缘两点的长度比，得到第一比例系数和第二比例系数，通过第一系数将图像中测量得到的冠幅尺度转换为实际冠幅尺度，通过第二系数将图像中测量得到的冠幅面积转换为实际冠幅面积；本公开能够准确高效的测出冠幅尺度和面积，提高了冠幅测量的智能化、自动化和高效化，降低了人力成本。