THE RESEARCH LAYOUT OF IMAGE CONTROL POINTS FOR 1:1000 B LEVEL DIGITAL ELEVATION MODEL PRODUCTION BASED ON UAV IN PLAIN AREA
With the advent of the era of big data, traditional measurement techniques have been difficult to meet the information extraction required by contemporary measurement products, and light UAV （Unmanned Aerial Vehicles）was used to mapping is one of the development trends of aerial photogrammetry in China. When data is processed on aerial photography, the control points in the measurement area directly affect the accuracy of the later mapping results as the basis of mathematical calculation. However, the traditional aerial photogrammetry lays out the number of image control points according to a wide range of industry specifications, For example, lay Leveling control point at four corners + a row of elevation control points is lay at both ends of the area and lay Leveling control point at four corners + two vertical framed air routes at both ends of the zone (Zhang, J. Q., 2009),there are no specific method for the number of image control points to achieve a certain scale accuracy. As a result, there are too many or too few image control points in different topography and different scales. Measured by the error, image point density and reasonable layout of the data acquisition of the Trimble UX5 UAV, The causes of the errors are analyzed, and the precise data are obtained by comparing the experiments. Based on this, the relationship between changing the density of image control points and reasonable location is analyzed through the typical plain survey area of 0.718 km 2. Designing four layout schemes of Image control points, taking the national standard as the standard, four groups of data are studied by comparing and analyzing GPS acquisition data with photogrammetry mapping data of Wuhan VISIONEK INC MapMatrix software. Through experimental analysis, the results show that the experimental data show that the light UAV can satisfy the production of 1:1000 B level digital elevation model in plain area when the image resolution is 350 dpi, the line height is controlled at 180 ± 10 m and the density of image control point is more than 9/km 2. At the same time, this image control point layout method is used reasonably can reduce the workload of the field, improve work efficiency, and also help to speed up the calculation of huge amount of aerial survey data so as to produce high-precision digital products.