本文選題：虛擬大平面靶標 + 小尺寸靶標組合��； 參考：《南昌航空大學》2017年碩士論文

【摘要】：基于立體視覺的測量系統(tǒng)被廣泛應用于工業(yè)、農業(yè)、國防等領域,攝像機標定是其關鍵步驟,標定的精度直接決定整個測量系統(tǒng)的精度,因此,研究高精度的攝像機標定技術對提高立體視覺測量系統(tǒng)的精度具有重要意義。本課題組在開展直升機旋翼槳葉運動參數測量研究時,發(fā)現傳統(tǒng)較高精度的攝像機標定方法在大視場環(huán)境下,標定精度不理想。據此,本文分析了影響基于立體視覺大視場攝像機標定精度的影響機理,采用虛擬大平面靶標(Virtual Large Planar Target,簡稱VLPT)研究了大視場攝像機標定技術,并系統(tǒng)分析了標定精度的影響因素。主要工作內容及其研究成果如下:(1)構建了大視場攝像機標定方法的實驗驗證系統(tǒng)。根據標定方法的驗證要求,分別從硬件、軟件和靶標三個方面,設計出實驗驗證系統(tǒng)。硬件平臺包括視覺模塊和數據處理模塊;軟件平臺分為圖像采集模塊、攝像機標定模塊和標定精度測試模塊;分別從靶標的類型、標記點的類型、標定點的個數、靶標的定位、標定點的排序五個方面,設計出8*8圓形標記點二維,且?guī)в邪袠硕ㄎ稽c和排序定向點的靶標。該實驗驗證系統(tǒng)為驗證本文方法的有效性和分析標定精度的影響因素提供基礎保障。(2)提出了基于VLPT的大視場攝像機標定方法。首先,利用多個相互獨立的小尺寸靶標(Mutually Independent Small Target,簡稱MIST),獲取多張標定圖像;其次,針對每張標定圖像,采用定位標記點圓心的方法,找到各個MIST,并為其上標定點進行排序和編號;再次,設定虛擬平面,通過在該平面上找到每個標定點對應虛擬點的方式,將多個MIST聯系到一起,構造出每張標定圖像相應的VLPT;接著,利用已獲得的多個VLPT,計算出攝像機參數,并通過非線性優(yōu)化算法對標定參數進行全局優(yōu)化;最后,將本文方法與傳統(tǒng)標定方法進行對比實驗,結果表明:本文方法的標定精度,與大尺寸靶標的標定精度相近,且明顯高于小尺寸靶標的標定精度。(3)分析了VLPT標定方法精度的影響因素。根據研究本文方法的過程,分別從標記點的定位精度、靶標的擺放方式、MIST的大小、標定圖像對的數目四個方面分析其對標定精度的影響機理,采用理論分析與實驗驗證相結合的方式,得出了以下結論:1)標記點的定位精度對標定參數的獲取過程影響不大,但嚴重影響了待測點的三維信息計算結果;2)通過“米字”形擺放方式,選取靶標面積為245mm*245mm的MIST,通過8對標定圖像,可以獲得較高的標定精度。這為本文方法的合理使用提供了指導性的建議,進一步提高了本方法的標定精度。
[Abstract]:The measurement system based on stereo vision is widely used in the fields of industry, agriculture, national defense and so on. Camera calibration is the key step. The precision of calibration directly determines the accuracy of the whole measurement system. It is very important to study the camera calibration technology with high precision to improve the precision of stereo vision measurement system. In the research of helicopter rotor blade motion parameter measurement, our group found that the traditional camera calibration method with high accuracy is not ideal in large field of view. Based on this, this paper analyzes the influence mechanism of camera calibration based on stereo vision, and studies the calibration technology of large field camera by using Virtual Large Planar Target, a virtual large plane target. The influencing factors of calibration accuracy are analyzed systematically. The main work and research results are as follows: 1) an experimental verification system for large field camera calibration method is established. According to the verification requirements of calibration method, the experimental verification system is designed from three aspects: hardware, software and target. The hardware platform includes visual module and data processing module, the software platform is divided into image acquisition module, camera calibration module and calibration precision testing module. There are five aspects in the ranking of marked points, and the two dimensional target with target location and sort orientation point is designed for 8 ~ (8) circular marking points. The experimental verification system provides a basic guarantee for verifying the effectiveness of the proposed method and analyzing the factors affecting the calibration accuracy. (2) A large field of view camera calibration method based on VLPT is proposed. Firstly, multiple calibrated images are obtained by using several independent small Independent Small targets (MISTs). Secondly, for each calibrated image, the method of locating the center of the mark point is used. Find each MIST, sort and number its superscript points; third, set the virtual plane, and associate multiple MIST together by finding the corresponding virtual point of each marker point on that plane. The corresponding VLPTs of each calibrated image are constructed. Then, the camera parameters are calculated by using the obtained VLPTs, and the calibration parameters are optimized globally by nonlinear optimization algorithm. The experimental results show that the calibration accuracy of this method is similar to that of large scale target. The accuracy of VLPT calibration method is obviously higher than that of small size target. According to the process of studying the method in this paper, the mechanism of influence on calibration accuracy is analyzed from four aspects: the positioning accuracy of marking points, the size of MIST and the number of calibrated image pairs. By combining theoretical analysis with experimental verification, it is concluded that the accuracy of tagging points has little effect on the acquisition of calibration parameters. However, the result of 3D information calculation is seriously affected. By means of "meter word" arrangement, the high calibration accuracy can be obtained by selecting 245mm*245mm whose target area is 245mm*245mm, and by using 8 pairs of calibrated images. This provides guidance for the rational use of this method and further improves the calibration accuracy of the method.
【學位授予單位】：南昌航空大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP391.41

【參考文獻】

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1 呂耀文;劉維;徐熙平;安U，

本文編號：1779834