GPS//INS data direct directing precision assessment method

Abstract

The invention discloses a GPS / INS data direct orientation precision evaluation method, which takes photogrammetric emphasis equation collinearity equation as base and a multi-piece forward intersection of a bundle method as theory basis; the evaluation method is combined with the least square principle for obtaning the coordinate of a ground control point object by compensating calculation; and then a comparison with the actually measured coordinate of the ground control point is carried out for obtaining the error value of the coordinate by the statistics so as to evaluate the direct orientation precision of the outer orientation elements obtained by the GPS / INS system. The method has high evaluation precision and small measurement error, and the evaluation result can be used for manufacture practice directly, thus being capable of effectively avoiding the measurement error of the picpointed coordinate added in manual stereomeasurement; and the algorithm is not limited by image number.

Description

technical field [0001] The invention relates to the technical field of photogrammetry, in particular to a GPS / INS data direct orientation accuracy evaluation method. Background technique [0002] Obtaining the outer orientation elements of images is one of the key issues in photogrammetry. Many photogrammetry workers have been working hard to solve the problem of how to quickly and efficiently acquire the outer orientation elements of images. For a long time, people have mainly used aerial triangulation technology to indirectly solve the external orientation elements through a large number of field control points. The above method not only wastes money, but also prolongs the mapping cycle, which seriously affects the urgently needed data for national economic construction. Since the 1990s, the international photogrammetry community has begun to study the use of GPS / INS integrated navigation system (that is, GPS / INS system: a combined system of GPS system and INS inertial nav...

AI Technical Summary

Problems solved by technology

But there are two deficiencies in this method: 1. Due to the errors in the external orientation elements obtained by the GPS / INS system, there is a large parallax in the stereograph, and it is difficult to perform stereographic mapping. Under the influence of parallax, it is impossible to The correct measurement of the required ground control points leads to a large error in the measurement of the coordinates of the image points. In this way, a large part of the error of the measured ground control point coordinates comes from the influence of the error of the image point coordinates, which cannot be strictly evaluated. Data Quality for Outer Orientation Elements

2. A check point on the ground will appear in multiple stereo image pairs. It needs to be manually observed model by model, and then the coordinate values ​​obtained by multiple model observations are adjusted to obtain the final coordinate value, which can be compared with the coordinates of the actual measurement point to be more objective. It is a very labor-intensive and time-consuming task to accurately evaluate the quality of external orientation elements, which not only wastes money, but also increases the time for quality evaluation

However, there are two disadvantages as follows: 1. Experiments have proved that this method cannot meet the actual production conditions of photogrammetry, and is only a mathematically idealized two-line forward intersection. It is impossible to really intersect together, only the theoretical image point coordinate data calculated by the same ground control point and the outer orientation elements of the left and right slices through the collinear equation, and then combined with the outer orientation element data of the left and right slices The mathematical model of the method is only in line with the calculation of the front intersection

Even if the high-precision aerotriangulation encryption result data is used, the error of the object space coordinates of the ground control points obtained through the forward intersection calculation method is very large, especially the elevation error is large, which basically does not conform to the actual situation and cannot reflect the outer azimuth element data quality, so the data quality of GPS / INS cannot be correctly evaluated, and the algorithm is not rigorous enough

2. The point projection coefficient method is only limited to the intersection of two fronts, and cannot realize the intersection of multiple rays, which is limited by the number of images

It is precisely because of the above shortcomings of this method that it can only be used as a theoretical forward intersection model method, and cannot be really used for direct orientation accuracy evaluation of actual GPS / INS data.

According to the statistical results of the accuracy of the orientation of the outer azimuth elements of the photo obtained by conventional aerial triangulation, the aeronautical accuracy is sufficient to meet the specification requirements in hilly areas; however, the outer azimuth element data and image points For the coordinate data, the accuracy statistical results obtained by the intersection of two slices in front of the point projection coefficient method greatly exceed the specification requirements, and are even unreasonable. It can be seen that the method of intersection of two slices in front of the point projection coefficient method cannot correctly evaluate the outer orientation element data Quality, cannot be used for the accuracy evaluation of the direct orientation of the external orientation elements obtained by GPS / INS

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