【摘要】：攝像機(jī)標(biāo)定是攝像測(cè)量的基礎(chǔ)和關(guān)鍵步驟,攝像系統(tǒng)的微小誤差在測(cè)量結(jié)果中可能被放大成千上萬(wàn)倍,所以要得到高精度的測(cè)量結(jié)果,必須對(duì)攝像系統(tǒng)進(jìn)行高精度的標(biāo)定。攝像機(jī)標(biāo)定一般是通過(guò)空間位置精確已知的控制點(diǎn)與其對(duì)應(yīng)的二維圖像點(diǎn)之間的關(guān)系建立方程組,解算攝像機(jī)的內(nèi)外參數(shù)。但是在海上或者空中以及其他視場(chǎng)內(nèi)無(wú)法布置合作標(biāo)志的場(chǎng)景下,沒(méi)有控制點(diǎn)可以利用,以致現(xiàn)有的方法無(wú)法對(duì)攝像機(jī)進(jìn)行標(biāo)定,并且傳統(tǒng)的標(biāo)定方法在測(cè)量大范圍遠(yuǎn)距離的目標(biāo)時(shí)會(huì)因?yàn)槟Ｐ秃退惴ǖ脑蛞胼^大誤差。針對(duì)上述情況,本文分解成視場(chǎng)內(nèi)無(wú)控制點(diǎn)的攝像機(jī)標(biāo)定方法、依賴深度信息的畸變模型以及利用直線畸變特性去像差的新方法等三個(gè)問(wèn)題進(jìn)行解決。由于攝像機(jī)內(nèi)參數(shù)的標(biāo)定可以在實(shí)驗(yàn)室內(nèi)高精度地完成,所以本文主要針對(duì)外參數(shù)的標(biāo)定,并提出了兩種標(biāo)定方法:1)基于坐標(biāo)系轉(zhuǎn)換的標(biāo)定方法,其基本思路是攝像機(jī)固定在剛性平臺(tái)上,標(biāo)定出攝像機(jī)相對(duì)于剛性平臺(tái)的位置和姿態(tài),然后將剛性平臺(tái)整體移動(dòng)到測(cè)量位置固定安裝,標(biāo)定出剛性平臺(tái)相對(duì)于測(cè)量位置的世界坐標(biāo)系的位置和姿態(tài),然后通過(guò)坐標(biāo)系之間的轉(zhuǎn)換,解算攝像機(jī)在世界坐標(biāo)系下的位置和姿態(tài),即攝像機(jī)的外參數(shù)。2)基于激光直線的標(biāo)定算法,其基本思路是通過(guò)激光在視場(chǎng)內(nèi)創(chuàng)造若干條空間坐標(biāo)已知的直線,根據(jù)空間直線和像直線的對(duì)應(yīng)關(guān)系求解投影矩陣,從中分解攝像機(jī)的外參數(shù)。其基本做法是將激光發(fā)射器和全站儀鏡筒固聯(lián)在一起,激光發(fā)射器跟隨全站儀鏡筒轉(zhuǎn)動(dòng),使得激光線在攝像機(jī)像面的不同位置成像,并根據(jù)全站儀此時(shí)的指向參數(shù)轉(zhuǎn)換求解對(duì)應(yīng)激光直線的空間三維信息,然后根據(jù)激光直線在空間中的位置和在像面上對(duì)應(yīng)的位置之間的關(guān)系建立方程組,解算攝像機(jī)的外參數(shù)。本文針對(duì)用近距離的標(biāo)定結(jié)果測(cè)量遠(yuǎn)距離控制點(diǎn)時(shí)會(huì)存在較大偏差的現(xiàn)象,在針孔模型的基礎(chǔ)上,提出了一種像差系數(shù)依賴深度信息的畸變模型,并通過(guò)實(shí)驗(yàn)證明了該模型可以有效地提高測(cè)量的精度。此外,本文提出了一種利用直線畸變特性去像差的新方法:首先,利用直線畸變的對(duì)稱性,先將直線畸變后的曲線校正成理想直線,再根據(jù)理想成像直線和實(shí)際畸變直線的像點(diǎn)之間對(duì)應(yīng)的關(guān)系計(jì)算不同半徑對(duì)應(yīng)的畸變因子,然后根據(jù)這組數(shù)據(jù)擬合并比較各種徑向畸變模型。本文為攝像機(jī)在視場(chǎng)內(nèi)無(wú)控制點(diǎn)的情況下對(duì)大范圍遠(yuǎn)距離測(cè)量的問(wèn)題提供了有利的理論和技術(shù)支持,拓展了傳統(tǒng)攝影測(cè)量的應(yīng)用范圍,有廣闊的工程前景。
[Abstract]:Camera calibration is the basis and key step of camera measurement. The small error of camera system may be magnified by thousands of times in the measurement result. Therefore, in order to obtain the high precision measurement result, the camera system must be calibrated with high accuracy. Camera calibration is usually based on the relationship between the control points and the corresponding two-dimensional image points, and the internal and external parameters of the camera are solved. But in situations where cooperative signs cannot be placed at sea or in the air or in other fields of view, there are no control points to be used, so that the existing methods cannot calibrate the cameras. And the traditional calibration method will introduce a large error because of the model and algorithm when measuring the target in a wide range and long distance. In view of the above situation, this paper decomposes three problems: camera calibration method without control point in the field of view, distortion model dependent on depth information and a new method to remove aberration by using linear distortion characteristics. Since the calibration of camera parameters can be done in the laboratory with high precision, this paper mainly focuses on the calibration of external parameters, and proposes two calibration methods: 1) based on coordinate system transformation. The basic idea is that the camera is fixed on the rigid platform, the position and attitude of the camera relative to the rigid platform are calibrated, and then the rigid platform is moved to the measuring position and fixed installation. The position and attitude of the rigid platform in the world coordinate system relative to the measuring position are calibrated, and then the position and attitude of the camera in the world coordinate system are calculated by the transformation of the coordinate system. That is, the external parameter of the camera is based on the calibration algorithm of the laser straight line. The basic idea is to create some lines with known spatial coordinates through the laser in the field of view, and to solve the projection matrix according to the corresponding relation between the spatial line and the image line. Decomposes the external parameters of the camera. The basic method is to bind the laser transmitter and the total station tube together, and the laser emitter rotates with the total station mirror tube, so that the laser line can be imaged in different positions of the camera image plane. According to the transformation of the pointing parameters of the total station at this time, the spatial 3D information of the laser line is solved, then the equations are established according to the relationship between the position of the laser line in the space and the corresponding position on the image plane, and the external parameters of the camera are solved. Based on the pinhole model, a distortion model with aberration coefficient dependent on depth information is proposed in this paper, in view of the phenomenon that there is a large deviation in the measurement of remote control points by using the calibration results from close range, and based on the pinhole model, a distortion model with aberration coefficient dependent on depth information is proposed in this paper. The experimental results show that the model can effectively improve the accuracy of measurement. In addition, a new method of aberration is proposed. Firstly, by using the symmetry of linear distortion, the curve after distortion is corrected into an ideal line. Then the distortion factors corresponding to different radii are calculated according to the relationship between the image points of ideal imaging lines and actual distorted lines, and then the various radial distortion models are combined and compared according to the data set. This paper provides a favorable theoretical and technical support for the problem of large-scale long-distance measurement without control points in the field of view, expands the application of traditional photogrammetry, and has a broad engineering prospect.
【學(xué)位授予單位】：國(guó)防科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TB853.1
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本文編號(hào)：2254930