A new code flag method based on coordinate quadrant in vision measurement

The code flags are designed to address the image matching problem in the close-range photogrammetry. However, the traditional designs are complex, large computation, and low identifiable. What is more, they can not meet the requirement of the measurement of large areas, large objects and complex objects. A new code flag method based on coordinate quadrant in vision measurement is designed to meet the urgent need of the accuracy and the efficiency in this paper. First of all, the code flags are rectangle and designed with black background and white flags, in which there are three white circles that are placed in a certain position, and at least one but not more than 4 white-based arcs that are intercepted on the same ring. The largest circle of the three white circles is in the center of the pattern, and the other two are same size, one of them is near from the center circle, while the other one is a little farther away from the center circle, and the two lines between each smaller circle's center and the center of center circle is a vertical connection. Then a Cartesian coordinate system is set up under the location of solid circles in the pattern. Next encode from the first quadrant in clockwise order in the built Cartesian coordinate system. And finally the design of code flag based on coordinate quadrant is implemented according to the algorithm. Compared with the traditional flags, the code flag method based on coordinate quadrant in vision measurement in this paper is simple, easy and fast to the information extraction. And there are various advantages, such as small noise and other interference factors, low-intensity work, accurate identification of flags and precise position.