Research On Method Of Constructing Terrain Model With Single-lens Flexible Angle Oblique Photography For Consumer Unmanned Aerial Vehicle

With the continuous development of Unmanned Aerial Vehicle(UAV)and computer software and hardware technology,UAV oblique aerial photography to construct highprecision terrain models is widely used in many fields.Consumer rotary drones have the advantages of low cost,easy control,low altitude,no need to apply for airspace,and free adjustment of the lens angle in low-altitude aerial photogrammetry,and they can operate flexibly in complex terrain and airspace.Aerial photography methods that do not limit the fixed angle and direction of professional oblique aerial cameras.Use consumer drones to study the construction of terrain models for single camera and multi-directional oblique photography of different terrain.Analyze the accuracy that can be achieved by different aerial photography methods to construct the terrain model when the number of control point schemes is different,Analyze and discuss the accuracy that can be achieved by different aerial photography methods to build the terrain model when the number of control point schemes is different.Provide method reference for reducing workload,improving accuracy and saving costs.The author demonstrated the feasibility of constructing a model of single-lens oblique photography by analyzing the geometric principles of oblique photography and the key techniques for constructing a terrain model.He studied the method of setting control points and established a basic calculation model of oblique angle and aerial photography parameters.Then use the consumer drone DJI Phantom 4 Pro single camera flexible angle to use a variety of different oblique photography methods for oblique aerial photography of different height difference terrain,with SfM-MVS(structure from motion with multi-view stereo)method to build a terrain model and analyze its accuracy.Analyze the oblique aerial method from the angle,direction,aerial area,altitude,and control point layout,and propose a 70 ° and 45 ° inclined cross aerial photography method to build a model of the stacked terrain formed by urban construction.For gully terrain,it is proposed to reduce unnecessary aerial photography directions and areas,simulate conventional 45 °inclined aerial photography,approximate vertical slope inclined aerial photography,and different height aerial photography to build models,Calculated the relationship between the oblique angle of different aerial photography methods and aerial photography parameters is during aerial photography.Analyze the accuracy of the terrain models constructed by different aerial photography methods at different numbers of control points,and summarize the appropriate aerial photography methods and control point layout schemes for different terrains.Research indicates: 1)The terrain with small undulations is suitable for constructing a model using 70 ° inclined cross aerial photography.When there are only five control points at the four corners and the center,compared with vertical downward aerial photography,it can improve the accuracy of elevation and volume measurement,and it has richer Texture features;2)The undulating hilly and gully terrain can reasonably reduce the aerial photography direction and area based on the conventional five-direction oblique aerial photography,and can build a high-precision terrain model;the oblique aerial photography approximately perpendicular to the side slope is inclined relative to the commonly used 45 ° It has better model accuracy,especially for a small number of control points;Different aerial height aerial photography can improve the ground resolution,but the accuracy has not improved to a certain extent.3)Oblique aerial photography,compared with vertical downward aerial photography,can mainly improve elevation accuracy.Hilly and gully terrain only has 5 control points on the top of the slope,no valley control points are needed,and high accuracy can be achieved during oblique aerial photography.Consumption rotary drones use a single-lens flexible angle to optimize and improve traditional oblique photography methods,and formulate oblique aerial photography solutions with different angles,directions and aerial photography areas for different terrains,with more reasonable accuracy and fewer Data volume can reduce economic costs and technical requirements.The proposed oblique aerial photography method and control point layout method have certain reference value for the construction of terrain models with different accuracy in production practice.