EVALUATING IMAGE QUALITY OF SMALL FORMAT AERIAL PHOTOGRAPHY SYSTEMS

The use of small format systems for aerial photography as an alternative to employing the more customary larger 230×230 mm format cameras continues to gain acceptance in a number of applications on the basis of the lower operating costs involved. The reduced costs and relative ease of operation with small format systems can attract unskilled operators who, by producing inferior photographic coverage, may delay the more widespread introduction of smaller systems for photo-interpretation and photogrammetric surveys of local sites. Anticipating the need for a flying and photography specification that would serve the needs of all interested parties, a series of laboratory trials were undertaken in conjunction with a literature review to quantify the comparative image quality performance of both large and small format systems. The spatial resolution of a typical small format system was assessed by photographing a low contrast resolution target using a collimator-based system and also by directly recording the target at a predetermined reduction scale. Comparative results between the two methods of evaluation are assessed and a comparison is made with the performance of larger format cameras.     

MEDIUM AND SMALL FORMAT PHOTOGRAPHY FOR THE MAINTENANCE OF NATIONAL MAPPING

In order to realise the full potential of photogrammetry for national map revision, photographic acquisition lead times and, where possible, costs must be significantly reduced. In this paper a review of alternative platform and camera configurations is made and tests are undertaken utilising simulated data and medium format data taken from an existing project. The results suggest that the medium format camera and helicopter combination may have much to offer while the small format camera and microlight aircraft systems have yet to be developed into an effective data acquisition and map compilation system.     

SMALL FORMAT AERIAL SURVEYS FROM LIGHT AND MICROLIGHT AIRCRAFT

Small format (SF) cameras, fitted to light or microlight aircraft, can provide an economic and convenient alternative to the more expensive conventional mapping systems. Further advantages accrue from the use of wider aperture lenses, an extensive range of easily available films and simplijed processing. These advantages can be exploited by employing light aircraft for small survey missions, such as map revision, and desktop photogrammetric systems dedicated to handling SF imagery. In this paper, an account is given of a research study involving SF map revision survey photography, using a modern microlight aircraft and a 70 mm metric camera.     

THE BENEFITS OF FORWARD MOTION COMPENSATION FOR AERIAL SURVEY PHOTOGRAPHY

Two of the speakers at a one-day symposium, held on 31st October, 1990 and concerned with the adoption of new equipment and techniques, comment on the introduction of forward motion compensation in air survey cameras and on a specification for architectural photogrammetry.     

EVALUATION OF SPACELAB PHOTOGRAPHY FOR SMALL SCALE MAPPING

The paper presents an assessment of the results of a practical investigation into topographic interpretation from photography taken from the Spacelab Mission launched on 28th November, 1983. Hunting Surveys Ltd. had carried out mapping at 1:100 000 scale of part of Oman from photography taken in 1981 and stereoscopic cover of this area from Spacelab was available, so providing the opportunity of a comparison of the interpretation with the existing mapping.     

SOME OBSERVATIONS AND RECOMMENDATIONS FOR THE FUTURE OF AERIAL COLOUR PHOTOGRAPHY

The colour photograph requirements of the photogrammetrist and the photo-interpreter are not always compatible. The author puts forward suggestions for improving the quality and reducing the cost of photography for interpretation purposes, based on the use of 70 mm film cameras. He found supporting evidence for this point of view during his visit to the United States as the result of the award of a Winston Churchill Fellowship in 1969.     

CENSUS OF GREY SEALS BY AERIAL PHOTOGRAPHY

The factors determining resolution in aerial photography of wildlife concentrations are considered and two developments that improve resolution with inexpensive equipment are described. Firstly, a rocking camera mount has been constructed that compensates for apparent image motion resulting from forward movement of the aircraft. The mount allows slower shutter speeds to be used so that aerial surveys can be conducted using high resolution colour film under poor light conditions. Secondly, critical prefocusing to the survey flying height is carried out, even for lenses of short focal length. Aerial photography of grey seal breeding colonies is used to illustrate these developments.     

加快四川省航空摄影的方法初探

本文提出加快四川省航空摄影的重要性，根据四川的气候条件，提出具体可航摄的季节和加快航摄进程及提高航摄质量的有关解决办法。     

超小比例尺彩红外高空摄影应用探讨

本文介绍了国内外超小比例尺彩红外高空摄影像片应用现状,并对它的光谱分辨率、空间分辨率、综合分辨率、专题表达能力、成本等进行了较深入的分析,以探讨其应用于环境与资源调查的技术经济性能。研究表明,超小比例尺彩红外高空摄影像片的应用有着广阔的前景。