地面检校场的非量测型数码相机检校

由于相机检校作为非量测型数码相机应用于摄影测量前的必经步骤,其精度直接决定着后续测图的精度,因此针对传统的相机检校方法不能较真实地反映相机的物理状态、检校精度不高的问题,该文给出了基于地面检校场进行检校的流程,并以和静县数据为例,将该方法的检校精度与基于室内三维检校场以及基于纯平液晶显示器的检校精度进行了对比。实验表明:经该方法检校出来的相机参数精度更高,能够满足大比例尺测图要求。     

相机三维检校场的精密测量与稳定性分析

为满足摄影测量中相机检校的需要,选用一种室内相机检校场的精密测量方法与实验分析方法,对相机检校场进行检校。根据山东科技大学室内三维检校场中标志点的排列规则,点数众多的实际分布特点,选用高精度的经纬仪测量系统,选取最佳的仪器和基准尺摆放位置对检校场内的标志点进行测量。利用统计检验的方法对标志点点位的稳定性进行分析,判断出标志点稳定可以满足相机检校的需要。     

无人机非量测相机检校方法研究

无人机搭载的非量测相机光学系统不稳定、畸变差大、内方位元素未知,难以满足大比例尺测图精度要求。本文通过建立高精度室内相机检校场,基于直接线性变换公式编写了非量测相机检校程序,根据解算得到的畸变参数对相机进行了改正,使之适用于大比例尺航空摄影测量成图,并通过实际项目验证了该方法的有效性。     

极坐标法在非量测相机检校场控制测量中的应用

分析室内检校场精度的常用测量控制方法,将极坐标应用于非量测相机检校场控制测量精度分析,研究其控制过程和精度误差。通过应用于铁路隧道衬砌表面状态检测与隧道限界测量系统,证明了文中方法具有较高的控制精度,可以满足一般工业摄影测量任务的需要。     

非量测型数码相机检校及量测精度分析

结合能够准确刻画相机物理特性的系统误差模型——Australis像差模型,对共线方程进行了改化。基于摄影测量光束法区域网平差理论,设计了相机检校的技术流程,利用自行开发的检校软件对普通数码相机进行了相机自检校处理及精度分析。试验结果表明,利用文中的相机检校处理流程和方法,可对常规普通数码相机进行可靠的、高精度的标定,以满足近景、低空摄影测量的精度要求。     

小像幅航片区域网平差初探

随着摄影测量技术的发展，用轻型气机装载非量测相机进行航空摄影测量的方法受到了测绘工作者的极大关注，它将具有广阔的应用前景，但也蕴藏着丰富的研究内涵。本文介绍了用日产Bronika SQ-A120型非量测相机对南极中山站所在的拉斯曼丘陵测区1：4万摄影比例尺小像幅航片进行加密的结果。通过用WuCAPS软件的带3个附加参数的自检校光束法区域网平差获得了实地上平面±2.829m，高程±4.973m的加密精度。文章的最后，对小像幅航片摄影测量加密的精度进行了分析，得出了初步结论。     

基于多片空间后方交会的CCD相机检校

近年来,CCD相机逐步应用于近景摄影测量、低空摄影测量。影响摄影测量成果精度的重要因素之一是相机的技术参数,因此相机技术参数的检校是保证成果质量能否满足精度要求的关键问题之一。文中通过单片空间后方交会和多片空间后方交会的比较试验,分别对两种方法实施了精度分析和可靠性分析,总结得出多片空间后方交会是一种更为可靠的CCD相机检校方法,且运用多片空间前方交会方法进一步验证了多片空间后方交会检校成果的可靠性。     

基于二维DLT的非量测相机检较

非量测数码相机由于价格低廉、使用方便等原因成为近景摄影测量获取影像的主要设备之一。但非量测相机的内方位元素和畸变系数未知,不能直接利用共线方程进行解析计算,因而必须对相机进行检校。而相机参数检校成果质量的高低直接关系着能否满足测量精度的要求。本文提出了基于二维直接线性变换(DLT)的相机标定算法,利用平面控制点解算出像点坐标和相应物点物方空间坐标之间的线性关系,再结合内方位元素及畸变参数的解算进行迭代,以得到满足一定精度要求的相机参数(x0,y0,f,k1,k2,p1,p2),并用MATLAB加以实现。     

基于DLT的数码相机检校方法

近年来,普通数码相机逐步应用于近景摄影测量、低空摄影测量,影响其成果精度的重要因素之一是相机的内参数,因此相机参数的检校是保证成果质量能否满足精度要求的关键问题之一。提出了数码相机的检校理论和方法,利用直接线性变换模型法进行实验,采用反复迭代的方法,获得相机像主点坐标、主距以及畸变系数。通过实验验证了该方法的精度和可靠性,获得了较好的检校精度。     

室内三维相机检校场温度改正阈值研究

室内三维相机检校场可以用于检校量测型相机或非量测型相机的内方位元素、光学畸变,以及多相机组合拼接参数。受温度变化影响,检校场观测标志载体发生热胀冷缩,观测标志发生相对位置变化,影响相机检校精度。通过采用经纬仪工业测量系统对检校场观测标志进行高精度测量,在不同温度条件下对检校场开展周期性观测,得出检校场标志点载体钢筋混凝土和金属挂杆的热膨胀系数,根据待检校相机的类型,计算出检校场需要达到的精度要求,确定检校场坐标温度改正阈值。     

立体测绘型双翼民用无人机航空摄影系统的实现与应用

按照领域专用、性价匹配的思想,设计并实现了一套满足小区域大比例尺地形图立体测绘要求的无人机航空摄影系统。该系统以双翼无人机为遥感平台,以数字相机为传感器,配置3轴稳定云台,直接获得数字航空影像,具有自主飞行、低空作业、无需机站支持、起降距离短、滑翔性能好等特点。系统包括双翼无人机、飞行自动控制与安全、CCD数字相机、稳定云台、空地无线通讯、地面站和数据处理等7个子系统。分别介绍了系统的总体结构和各子系统的技术状况;分析和比较了系统的GSD、像点移位、基高比等关键参数在保证成像质量和成图精度方面的合理性;报告和展示了系统在广州新客站、丹江口文物考古测量工程的试验情况和部分成果;最后对系统的改进提出了建议。     

High-accuracy photogrammetric technique for human spine measurement

Close range photogrammetry has been recognised as an essential tool for the capture of high-accuracy spatial data for medical applications, in particular work involving dynamic human body parts such as limbs. Offline and online photogrammetric systems are readily available for a number of common applications. However, off-the-shelf systems are not always appropriate because of project site conditions. To achieve high measurement accuracy in a field environment, a modified field camera calibration technique was introduced. The technique is particularly important where each camera is limited to one captured image during calibration, as the camera and the calibration testfield are in fixed positions. In this paper a custom-built imaging system designed for the study of the human spine in an outdoor environment is introduced. The discussion addresses: (1) imaging system design; (2) modified field calibration techniques; and (3) a case study on human spines. Two field camera calibration techniques were evaluated, both of which improved the accuracy of the prototype system, the use of a detachable target board offering the best results. This modified camera calibration procedure has improved the 3D measurement accuracy from 1·25 ± 0·3 mm to 0·43 ± 0·1 mm. The improvement is at a level achievable in the laboratory. The technique is considered to provide accurate and reliable anthropometric landmark measurement at low cost. This was evaluated in a clinical setting where diurnal changes in spine length and contour were measured in a cohort of 30 university students. The capability of the technique to measure sagittal and frontal angular changes provides a novel way of examining changes in spine shape.     

利用差分GNSS获取高精度无人机影像外方位线元素

目前,微小型无人机遥感系统定位精度低,需要布设大量地面控制点,才能满足空三和测图精度要求,为提高无人机遥感系统影像的后期处理效率,文中研究利用差分GNSS模块,结合后差分算法提高POS数据精度,并通过位置标定、相机时间延迟改正等关键技术方法开展研究,最终获得高精度相机曝光时刻的位置信息,以此为基础,集成一套基于差分GNSS的无人机遥感系统。通过实验,最终实现以少量地面控制点获取高精度无人机影像外方位线元素,提高无人机影像后期处理效率,具有一定工程应用价值。     

Direct creation of construction drawings for Kwan-yin Statue by close-range photogrammetry

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Direct creation of construction drawings for Kwan-yin Statue by close-range photogrammetry

In order to provide the model point accuracy of ±2 mm, an extra high accuracy industrial control net with four surveying piers with accuracy ±0.1 mm was set up around the model. Tens of orientation marks have been placed on the different parts and measured with accuracy ±0.2 mm from the above-mentioned piers. The main four stereopairs taken with the P31 camera around the model are simultaneously processed on the BC2 analytical plotter. The accuracy of absolute orientation is better than ±0.9 mm. Finally, about 300 sections construction drawings have been directly offered, and the closerange photogrammetric data has been used for the design and construction of the statue.     

消费级无人机在大比例尺测图中应用与精度评价

以分别搭载大视场角普通相机和鱼眼相机的消费级无人机为例,在对相机的高精度标定基础上,选取典型丘陵和山地实验区分别对两种消费级无人机大比例尺测图能力进行实验和精度评价,结果证明消费级无人机在合理的航测方式下,其测图结果的空三精度、分辨率及高程精度均可满足国家1∶500大比例尺地形测图的精度要求,可以推广应用到小范围大比例尺测图和修测任务中。     

STEREOMICROSCOPE PHOTOGRAMMETRY FOR THE MEASUREMENT OF SMALL OBJECTS

A stereoscopic microscope has been used in combination with the body of a 35 mm camera to obtain stereophotographs, at scales up to 6:1, of objects only a few millimetres in size. Subsequent stereocomparator observations have been used to deduce height differences on the objects 10 a precision, for the mean of five sets of readings, of ±0.01 mm for closely spaced points. Using more widely separated points, the precision was estimated to be ± 0.05 mm. Depths were computed using × parallaxes after a number of parameters were fixed by calibration. The large convergence angle of the microscope axes was a crucial parameter; rotations about the camera axis were found to be significant variables.     

无人直升机面阵影像高精度对地定位

为提高无人机对地定位精度，必须对系统进行几何标定与补偿。首先进行了直接地理定位实验，检验系统在不经过任何标定时的直接地理定位精度；然后进行了自由网光束法平差实验，以验证无地面控制点时系统的定位精度；最后进行了POS辅助自检校光束法平差，对内方位元素变化、相机畸变、IMU安置角进行标定和补偿，并验证了系统误差补偿后的直接地理定位精度。实验结果表明，未经几何标定的无人直升机直接地理定位的精度可满足应急条件下测绘保障要求；少量地面控制点的辅助下定位精度远优于1:500比例尺地形图测图的要求，可用于常规测绘生产；系统误差补偿后，直接地理定位精度有明显提升:平面精度提高46.37%，高程精度提高62.49%；系统误差标定和补偿方法正确、有效，无人直升机具有很好的测绘应用前景。     

The specific character of limit errors in close range photogrammetry

Close-range photogrammetry is to determine the shape and size of the object, instead of it's absolute position. Therefore, at first, any translation and rotation of the photogrammetric model of the object caused by whole geodesic, photographic and photogrammetric procedures in close-range photogrammetry could not be considered. However, it is necessary to analyze all the reasons which cause the deformations of the shape and size and to present their corresponding theories and equations. This situation, of course, is very different from the conventional topophotogrammetry. In this paper some specific characters of limit errors in close-range photogrammetry are presented in detail, including limit errors for calibration of interior elements for close-range cameras, the limit errors of relative and absolute orientations in close-range cameras, the limit errors of relative and absolute orientations in close-range photogrammetric procedures, and the limit errors of control works in close-range photogrammetry. A theoretical equation of calibration accuracy for close-range camerais given. Relating to the three examples in this paper, their theoretical accuracy requirement of interior elements of camera change in the scope of ±(0.005–0.350) mm. This discussion permits us to reduce accuracy requirement in calibration for an object with small relief, but the camera platform is located in violent vibration environment. Another theoretical equation of relative RMS of base lines (mS/S) and the equation RMS of start direction are also presented. It is proved that themS/S could be equal to the relative RMS ofmΔX/ΔX. It is also proved that the permitting RMS of start direction is much bigger than the traditionally used one. Some useful equations of limit errors in close-range photogrammetry are presented as well. Suggestions mentioned above are perhaps beneficial for increasing efficiency, for reducing production cost.     

BUNDLE TRIANGULATION IN ARCHITECTURAL PHOTOGRAMMETRY: THE BASILICA OF SAN FRANCESCO IN SIENA

Bundle triangulation is an efficient tool for spatial point determination in architectural photogrammetry. All the information available in image and object space may be introduced in a combined adjustment yielding high precision and reliability. Camera calibration performed simultaneously with the object restitution process enables the application of convenient and flexible imaging systems based on professional photographic technology. Thus the survey of monuments can be carried out rapidly with a minimum of personnel and equipment. The photogrammetric recording of the basilica of San Francesco in Siena is presented as an example of the application of this survey procedure. The field work was accomplished in a few days. The equipment used consisted of a partial metric camera, an engineering theodolite and a tape. The bundle adjustment results gave spatial object co-ordinates with a r.m.s.e. of ± 15 mm for a point.