Forest Area Measurement And Application Research Based On UAV

Forest resources monitoring,afforestation and forestation are important contents of forestry work.Inspection and verification of land parcel of forest harvesting,afforestation and expropriation are important measures for protection of forest resources,and rapid acquisition of these specific land areas is an important part of inspection and verification.Aiming at the problems of slow speed,low efficiency of conventional measurement methods,high equipment requirements,large amount of data and time-consuming of traditional unmanned aerial vehicle aerial survey.In order to quickly and conveniently acquire the actual area of a specific plot,solve the difficult problems of fast acquisition of specific forest area,and realize efficient inspection and verification of a specific plot.A method of land area measurement based on unmanned aerial vehicle single field panoramic image proposed in this paper.1.An improved camera calibration method is proposed to realize camera calibration and image distortion correction.The calibration method based on Zhang Zhengyou’s camera is improved.The focal length and pixel size are obtained by acquiring camera parameters,which are taken as known parameters.A linear imaging model is established to calculate the camera’s internal and external parameters matrix.A second-order radial and tangential distortion is introduced to establish a non-linear imaging model.Finally,the parameters are optimized iteratively and the optimal solution is obtained.2.The method of extracting specific region from panoramic image and counting its number of pixels is studied.The corrected panoramic image taken by the unmanned aerial vehicle is extracted by region extraction.Canny edge detection operator and morphological image processing method are used to eliminate the interference area and obtain a clear and complete region shape binary map.The number of pixels in the region is counted.Based on the internal and external parameters of the camera,the proportional relationship between the ground resolution and the pixel size is studied.The resolution of the image is calculated according to the known aerial height,pixel size and focal length,and the location of the image on the map is realized.3.A single panoramic image taken by the unmanned aerial vehicle is used to calculate the area of the plot.The results of the area measurement show that the variation law between the area calculation error and the altitude.The experimental results show that with the increase of Flight altitude of unmanned aerial vehicle,the calculation accuracy of the proposed method increases gradually at first,and then decreases gradually after reaching a peak value.The relative errors in the effective flight altitude are all below 10%.This method has practical significance for mountain operations requiring simple and fast operation and low accuracy.