The image point coordinates like the base (like a vitro point) can be obtained directly from the formula: XN = -f · C1 / C3, Yn = -f · C2 / C3.

The corresponding ground point coordinate of the like base (like a vitro point): xn, yn. How do you ask?

(1) Double-like space in front

(2) Single image space coordinates

What is the use of it?

>> Like the bottom point for POS system direct pair target positioning: integrated airborne POS system in integral multi-scale, Inertial Navigation System, INS) can directly determine the gesture information of the flight platform in the air remote sensing Get a wide range of applications. The external element element provided by the POS system can avoid the traditional beam method region network flat difference to realize the generation of direct pair target positioning and orthodontic image, and provide a fast acquisition, update, update, and various emergency surveylation of basic geographic information. It has become a must-have system for new sensors such as Lidar, ADS40. However, due to the installation, the coordinate axlation of the IMU does not remain strictly parallel, and there is a small angle deviation between the two coordinate axes, which is commonly referred to as a visual axis error or Eccentric angle, resulting in the external position angle element of the POS system to be used without direct use, and it is necessary to take a suitable check for error compensation to improve the accuracy of direct pair’s target positioning. The usual practice is to use flight check campus.

How did you do direct local target positioning?

One of the important development of contemporary photography measurement is to apply the designer theory to photographic measurement. Many scholars at home and abroad studied the camera standard for the point-based camera, and applied it to the “three-dimensional reconstruction” and literature Click to determine the in-camera orientation element and the external angle element. For aviation photography, the spatial set of lead vertical lines is called “like base” on the image, and is also a leading point of the projection center (taken station) and the flat coordinates and The camera coordinates (external line elements) are not related to the external angle elements of the image. Zhang Yong studied the triangular measurement of the introduction of the underlying point of control as a new type of control. Based on the above research ideas, this paper proposes a method of using the inventory of the IMU vision axis error to improve the POS system.

The external element element directly provided by the POS system is based on the WGS84 coordinate system. In order to avoid the error introduced by the coordinate conversion, the ground target positioning accuracy analysis is performed directly under the WGS84 coordinate system. Since this paper mainly discusses the image of the IMU vision axis error to be used for the land target positioning, it is mainly for the external azimuth element to process the translation error of the line element, and the outer angle element Three cases discussed: 1 did not corrected the vision axis error; 2 via the vision axis error correction; 3 via the vision axis error correction of the base point solved. In three cases, the single mode front will be used for the ground target positioning, and the results are listed in Table 1.

From the results in Table 1, it can be seen that the precision of the position of the POS external position element is low, mainly due to the difference due to the vision axis error, the direct positioning accuracy is obtained after the vision axis error is corrected It has greatly improved, and the plane accuracy has increased by about 87.8%, and the elevation accuracy has increased by about 68.7%. The two inspection school methods in the comparison table can also be found that after using the check campus and the visiting axis error of the POS, the position of the POS external angle element is used, the accuracy of the position is basically comparable to the medium error. This shows that the vision axis error that is solved like a base point can better correct the POS external angle element, effectively improve the direct pair positioning accuracy. This method does not need to set a specific check campus and ground control points, simply use the image covered with ground leading line information to achieve high precision pair positioning of the POS system without ground control.

### Research conclusion

>> Application of the base point constraint in the city’s large proportion of measuring: