Field Of Photogrammetry Research Articles

지상기준점을 이용한 비측량용 카메라 렌즈 캘리브레이션

최근 비약적인 기술발전을 통해 8,000만 화소급 디지털 카메라가 등장했으며, 비측량용 디지털 카메라가 사진 측량 분야에서 다양하게 활용되고 있다. 본 연구에서는 항공사진과 지상기준점을 이용하여 렌즈 캘리브레이션을 수행하였다. 항공사진은 35mm 렌즈가 장착된 CMOS 2,110만 화소급 비측량용 디지털 카메라를 헬리콥터에 설치하여 취득하였고, 지상기준점은 1:1,000 도화원도에서 선점하였다. 그 결과 렌즈에 대한 초점거리, PPA, 방사왜곡계수를 계산할 수 있었다. 또한 렌즈 캘리브레이션 전후에 항공삼각측량을 수행하여 지상기준점의 평균제곱근오차와 최대 잔차를 비교하였으며, 캘리브레이션 후 정확도가 매우 큰 폭으로 향상됨을 알 수 있었다. The most recent, 80 mega pixels digital camera appeared through the development of digital technology, and nonmetric digital cameras have been using in various field of photogrammetry. In this study, we experimented lens calibration using aerial photographs and ground control points. The aerial photographs were taken a non-metric digital camera which is CMOS(Complementary Metal Oxide Semiconductor) 21.1 mega pixels sensor and 35mm lens at a helicopter. And the ground control points were selected on the 1:1,000 plotting origin data. As a result, we calculated focal length, PPA(Principal Point of Autocollimation) and symmetric radial distortion coefficients from the lens. Also, RMSE(root mean square error) and maximum residual of the ground control points from the aerial triangulation were compared before and after calibration. And we found that the accuracy of the after calibration was improved very significantly.

입체영상 제작을 위한 비정렬 스테레오 영상의 정밀편위수정

The stagnant growth in 3D market due to 3D movie contents shortage is encouraging development of techniques for production cost reduction. Elimination of vertical disparity generated during image acquisition requires heaviest time and effort in the whole stereoscopic film-making process. This matter is directly related to competitiveness in the market and is being dealt with as a very important task. The removal of vertical disparity, i.e. image rectification has been treated for a long time in the photogrammetry field. While computer vision methods are focused on fast processing and automation, photogrammetry methods on accuracy and precision. However, photogrammetric approaches have not been tried for the 3D film-making. In this paper, proposed is a photogrammetry-based rectification algorithm that enable to eliminate the vertical disparity precisely by reconstruction of geometric relationship at the time of shooting. Evaluation of proposed algorithm was carried out by comparing the performance with two existing computer vision algorithms. The epipolar constraint satisfaction, epipolar line accuracy and vertical disparity of result images were tested. As a result, the proposed algorithm showed excellent performance than the other algorithms in term of accuracy and precision, and also revealed robustness about position error of tie-points.

A Structured-Light Approach for the Reconstruction of Complex Objects

Recently, one of the central issues in the fields of Photogrammetry, Computer Vision, Computer Graphics and Image Processing is the development of tools for the automatic reconstruction of complex 3D objects. Among various approaches, one of the most promising is Structured Light 3D scanning (SL) which combines automation and high accuracy with low cost, given the steady decrease in price of cameras and projectors. SL relies on the projection of different light patterns, by means of a video projector, on 3D object sur faces, which are recorded by one or more digital cameras. Automatic pattern identification on images allows reconstructing the shape of recorded 3D objects via triangulation of the optical rays corresponding to projector and camera pixels. Models draped with realistic phototexture may be thus also generated, reproducing both geometry and appearance of the 3D world. In this context, subject of our research is a synthesis of state-of-the-art as well as the development of novel algorithms, in order to implement a 3D scanning system consisting, at this stage, of one consumer digital camera (DSLR) and a video projector. In the following, the main principles of structured light scanning and the algorithms implemented in our system are presented, and results are given to demonstrate the potential of such a system. Since this work is part of an ongoing research project, future tasks are also discussed.

Monocular trajectory intersection method for 3D motion measurement of a point target

This article proposes a monocular trajectory intersection method, a videometrics measurement with a mature theoretical system to solve the 3D motion parameters of a point target. It determines the target’s motion parameters including its 3D trajectory and velocity by intersecting the parametric trajectory of a motion target and series of sight-rays by which a motion camera observes the target, in contrast with the regular intersection method for 3D measurement by which the sight-rays intersect at one point. The method offers an approach to overcome the technical failure of traditional monocular measurements for the 3D motion of a point target and thus extends the application fields of photogrammetry and computer vision. Wide application is expected in passive observations of motion targets on various mobile beds.

Performance Analysis of the SIFT Operator for Automatic Feature Extraction and Matching in Photogrammetric Applications

In the photogrammetry field, interest in region detectors, which are widely used in Computer Vision, is quickly increasing due to the availability of new techniques. Images acquired by Mobile Mapping Technology, Oblique Photogrammetric Cameras or Unmanned Aerial Vehicles do not observe normal acquisition conditions. Feature extraction and matching techniques, which are traditionally used in photogrammetry, are usually inefficient for these applications as they are unable to provide reliable results under extreme geometrical conditions (convergent taking geometry, strong affine transformations, etc.) and for bad-textured images. A performance analysis of the SIFT technique in aerial and close-range photogrammetric applications is presented in this paper. The goal is to establish the suitability of the SIFT technique for automatic tie point extraction and approximate DSM (Digital Surface Model) generation. First, the performances of the SIFT operator have been compared with those provided by feature extraction and matching techniques used in photogrammetry. All these techniques have been implemented by the authors and validated on aerial and terrestrial images. Moreover, an auto-adaptive version of the SIFT operator has been developed, in order to improve the performances of the SIFT detector in relation to the texture of the images. The Auto-Adaptive SIFT operator (A2 SIFT) has been validated on several aerial images, with particular attention to large scale aerial images acquired using mini-UAV systems.

ACCURACY PREDICTION FOR ORTHO‐IMAGE GENERATION

AbstractThis paper revisits the basic mathematical formulation of ortho‐image (digital orthophoto) generation. The main objective is to provide an approach for predicting the accuracy of an ortho‐image, according to the accuracy of the digital elevation model (DEM), control points and image measurements, the configuration of fiducial, tie and control points, and the ground slope. The approach is based on applying the well‐known law of error propagation to the mathematical model of ortho‐image generation. Although it may seem intuitive for professionals in the field of photogrammetry, such an approach is essential in the era when specialists in other fields use off‐the‐shelf software packages for ortho‐image generation. Simulations with the derived approach show that the accuracy of the ortho‐image is more sensitive to errors in image measurement of fiducial, tie and control points and ground coordinates of control points, than to DEM errors. Non‐standard configurations of fiducial, tie and control points further impair the accuracy. In addition, certain combinations of point location and ground slope might lead to unacceptably large error on the ortho‐image.

Modelling and representation issues in automated feature extraction from aerial and satellite images

New digital systems for the processing of photogrammetric and remote sensing images have led to new approaches to information extraction for mapping and Geographic Information System (GIS) applications, with the expectation that data can become more readily available at a lower cost and with greater currency. Demands for mapping and GIS data are increasing as well for environmental assessment and monitoring. Hence, researchers from the fields of photogrammetry and remote sensing, as well as computer vision and artificial intelligence, are bringing together their particular skills for automating these tasks of information extraction. The paper will review some of the approaches used in knowledge representation and modelling for machine vision, and give examples of their applications in research for image understanding of aerial and satellite imagery.

Digital image processing—The new technology for photogrammetry

Abstract Developments in digital computers have significantly changed the procedures and equipment now available in the field of photogrammetry. Photogrammetry is now entering an era in which digital image processing will play a major role in the tasks of extraction of information from images, leading to an increasing level of automation. Some commonly used procedures available for this processing are reviewed in the paper, and two examples describing the application of these procedures for determining elevations from SPOT satellite data and measurements of industrial components for industrial monitoring are given.

Digital Image Processing–The New Technology for Photogrammetry

Abstract Developments in digital computers have significantly changed the procedures and equipment now available in the field of photogrammetry. Photogrammetry is now entering an era in which digital image processing will play a major role in the tasks of extraction of information from images, leading to an increasing level of automation. Some commonly used procedures available for this processing are reviewed in the paper, and two examples describing the application of these procedures for determining elevations from SPOT satellite data and measurements of industrial components for industrial monitoring are given.

A discussion about the terminology “photogrammetry and remote sensing”

Nowadays is a very widely used term for the field of Photogrammetry. But when it is u~ed as the name of a learned society, of a published periodical or of a discipline in universities or colleges, some ambiguitias occur. For example, let us ask: Does the term represent one single discipline or two separate ones? Originally is defined as the science or art of obtaining reliable measurements by means of photographs. Based upon this definition, Photogrammetry Remote can be considered as two separate disciplines. This is because the former deals with obtaining geometric information of objects by photographic means, while the latter deals with obtaining physical information about an object or phenomenon through the use of electromagnetic radiation sensors. However, through developments , the 1950's photogrammetry has covered a broader range of activities thus developed into a new phase. This is evident by its revised definition recommended by the International Society of (ISP) in the year 1976. The definition reads as follows: Photogrammetry, for the purpose of the ISP, should be considered as the science technology of obtaining reliable information about physical objects the environment, through the process of recording, measuring interpreting photographs the patterns of radiant energy derived from sensor system. We see that in 1976 such a definition recommended for Remote Sensing. Finally in 1988, this same definition with a few minor changes was used again by ISPRS as the definition for the term Sensing. That is to say, a definition similar to that used for the term Photogrammetry indeed is used in 1988 for the term Sensing. In fact, we have here used the word and to join two identical terms. The American Society for Sensing (ASPRS) made the following statement recently, saying modern photogrammetry is

Information retrieval in the photogrammetry and remote sensing literature

Information retrieval requires a database and a host computer. Most scientific fields nowadays have their own database. However, in the field of photogrammetry and remote sensing we do not as yet have a comprehensive database. Information on the literature in our field is scattered over many databases, making retrieval cumbersome and expensive. This paper analyzes the present state of affairs and summarizes details for establishing ISPRS-IRS, the Information Retrieval System of the International Society for Photogrammetry and Remote Sensing, which is tailored to cover surveying and mapping, including remote sensing. ISPRS-IRS should be available online and should be free-of-charge, using the postcard approach. In order to decide whether there is at present really a need to implement ISPRS-IRS, the next phase should be to collect data to judge the capabilities, efficiency, reliability and costs of the bibliographic and factual information which is available at present.

Examination and Survey for Endurance and Fatigue of Operators in Operating the Plotting Instruments. (I)

The modern system in the field of photogrammetry has been established about 40 years back, that means, it has already passed since the wide angle camera and its plotting instruments have apperaed. The photogrammetrist can now have the chance to get their necessary inf ormations, and instruments from every places in the world. But we have never seen papers on the examination and survey for endurance and fatigue of operators in operating the plotting instrument. This surveys were conducted by the Pacific Aero Survey Co., Ltd. with the cooperations of research members belonged to Laborphy-siological Laboratory in May and June of 1967. 6 Operators and 6 Assistant of A-7 Aerograph and A-S plotting instrument were seclected as examiners for this experiment surveying every factors effecting to the human body in case of plotting works, and these results were analysed by the experts of physiology. In a series of three separated papers, these analysed procedures and results are discussed. This first paper deseribes only object, examined items, the effect of operators pose during plotting, fatigue examination, and examination for sleeping hour and the time taking the food for operators.

THE ALLIANCE OF ELECTRONICS WITH PHOTOGRAMMETRY

SummaryThe paper discusses, from a practical point of view, the increasingly close connection between photogrammetry and electronics. The subject is considered under three heads: Airborne Instruments, Field Instruments, and Laboratory Instruments. Brief examples of the use of various instruments and techniques are mentioned, with particular reference to the practical advantages and disadvantages. Desirable improvements and probable future developments are reviewed and conclusions as to the potentialities and limitations of electronics in the field of photogrammetry are drawn.

The Planning of Aerial Photographic Projects

Although there is a progressively developing literature in the field of photogrammetry, until the studies herein described were initiated, there was practically no information in regard to planning and estimating the cost of aerial photographic projects. This paper discusses the establishment of a photographic day, zones of similar weather characteristics, and a method of scheduling projects. The reliability of the representative photographic day is discussed. A method of estimating the cost of aerial photography is also presented.