18—23MSP 多光谱航空摄影技术

此项研究是国家科技攻关项目。在研究此课题以前,世界上采用的多光谱航空摄影机一直是小像幅的(大部分为6cmx6cm,代称为6MSP)。6MSP不能测图,分光“有害吸收”大,故图像质量差,且像幅小,飞行和后期加工量极大。本研究采用18cm×l8cm和23cm×23cm像幅航空摄影测量像机组成多光谱像机组,并设计了“截止滤光镜一特制感光胶片”组合的无“有害吸收”的分光系统,使本多光谱航空摄影像幅比6MSP加大了9倍和14.7倍,并能“一摄多用”,既能测图,又能进行资源调查和环境监测,其图像因无“有害吸收”,分光质量高,可供目视判读,也可输入计算机进行准确地物分类解译。18-23MSP是一项有效的航空遥感技术。     

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.     

CONSIDERATIONS OF SPECIFICATIONS FOR SMALL FORMAT AERIAL PHOTOGRAPHY

Following the success of the symposium held by the Photogrammetric Society on 31st March, 1987, a second one-day symposium was convened to give further support to the rapidly growing interest in the development of small format photography for aerial survey. This was held at Burlington House, London on 1st November, 1988. Over 70 people attended. Six of the papers are reproduced here, dealing with a range of topics including specifications for and navigation of small format aerial photography, the creation of digital terrain models from 35 mm photography, wildlife surveys in the Arctic and survey photography from model aircraft and tethered balloons.     

A LIBRARY OF PHOTOGRAMMETRICALLY SUITABLE AERIAL PHOTOGRAPHY IN THE COMMERCIAL SECTOR

The author draws attention to the public nature of an archive compared with the privacy of a collection in the commercial sector. He emphasises the nature of copyright as it affects the products of his own company and explains some of the characteristic features of a commercial operation involved in the acquisition and supply of aerial photography.     

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。     

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.     

PHOTOGRAPHY FROM SPACE

The Photogrammetric Society and the Remote Sensing Society held a joint symposium at Burlington House, London on 13th March, 1985. A number of papers were presented which related early experience gained with the use of Metric Camera photography taken from Spacelab in December 1983. Their authors described the Metric Camera experiment, the quality of satellite photography and presented and considered results from a number of applications in topographic and hydrographic mapping and land classification. It had been intended to include reports on the use of Large Format Camera photography taken in October 1984 but delays in release of this photography meant that insufficient time had elapsed,for the accomplishment of useful investigations.     

航线设计与设计结果的可视化仿真

介绍了一种基于定向理论的航线设计方法,利用设计结果实现了航摄仿真的技术与过程,讨论了实现航摄过程仿真预演功能对航摄工作的重要影响。     

LIMITATIONS OF RESOLVING POWER AS A MEASURE OF IMAGE QUALITY IN AERIAL PHOTOGRAPHY

Photography of models and modulation transfer function analysis have been used to investigate the common belief that in aerial photography large-scale images are preferable to small-scale images, even when the resolving power in terms of ground dimensions is the same. The belief was found to be justified for two extreme cases representing, respectively, a small scale, mainly grain-limited system, and a large scale, wholly lens-limited system, for which the ground resolutions were equal on three-bar targets of 3 to 1 contrast (modulation 0–5). Resolving power tests would have been misleading for these two systems even at a target contrast of less than 2 to 1 (modulation less than 0–3).