Forest Fire-Point Location Based on Bundle Adjustment of Double Images

Using a camera to obtain the stereo pair of digital photographs of forest area, and a three-dimensional electronic compass to measure the three-dimensional attitude angles at each instant shooting as the initial values, three dimensional coordinates of the forest fire-point was determined with bundle adjustment of double images. The experiments showed that the accuracy of locating fire-point reached 100 m, which meets the requirement of the forest fire prevention regulation. As this method does not require a known point to be a control point, the location accuracy is dependent on parallax error of corresponding image points, photographic baseline length, corner and photographic distance, etc. The coordinate positioning error increases with the photographic distance, and the error in the shooting direction is significantly greater than that in the other two directions. Fire point positioning accuracy will improve with the increase of photographic baseline length, and the influence of corner on the positioning accuracy of fire point is not evident. In the selection of photo station, photographic baseline length should be within 30-200 m, which ensures that the overlap between the left and right images falls in the interval of 60% to 80% and the images can correctly match each other.