COORDINATE ADJUSTMENT OF CONTROL TARGETS IN THE CALIBRATION SHEET FOR UAV CAMERA CALIBRATION
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Abstract
Camera calibration for mapping from UAV is an important process for determining the camera interior orientation parameters, which are used as a bridge to link rays from points on the image to the outside world. The camera calibration which utilizes a calibration sheet plotted by an inkjet plotter is a method that is mostly used in general. A calibration sheet size is approximately the size of an A0 paper and consists of control targets distributed throughout the entire sheet. In reality, the locations of the control targets are not plotted correctly. The error generated by the plotter can reach as much as 2 millimeters for a one-meter distance. This paper presents a procedure to use a steel ruler, which is an accurate device for measuring distances and has higher accuracy than an inkjet plotter, to check for positional error of the control target. The error is then used to adjust the target coordinates. The analysis of error of the adjusted coordinates of control targets are also presented.
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The published articles are copyright of the Engineering Journal of Research and Development, The Engineering Institute of Thailand Under H.M. The King's Patronage (EIT).
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