Analytical Photogrammetric Systems from Adam Technology

The features and applications of the low cost analytical plotters manufactured by ADAM Technology are described. The ADAM Technology products (the small format MPS-2 analytical stereoplotter, analytical conversions for Kern PG2 and Wild B8 analogue stereoplotter and the 230mm format Promap modular system) are discussed.     

APS解析测图仪的开发与应用

本文介绍了新开发的在ＡＰＳ解析测图仪上进行的自动定向、ＤＴＭ采集、近景摄影测量相对控制条件下的绝对定向等成果。     

Urban and Suburban Mapping With the AP190 Analytical Plotter

The AP190 analytical stereoplotter has been employed for two research projects concerned with the urban and suburban environment. In the first project, the suitability of the AP190 was assessed for comparing height readings between stereomodels of colour diapositives and colour paper prints, for collecting height data for a digital terrain model and for producing a land use map using a stereopair of part of Edinburgh under well controlled conditions. The second project dealt with the densification of minor control points by means of the BLOKK aerial triangulation package, followed by the digital mapping of a suburban area planned for land readjustment in Bangkok.     

THE VIVIAN THOMPSON STEREO-PLANIGRAPH

This short paper describes a design, hitherto unpublished, for an automatic stereoplotter conceived by Captain Vivian Thompson?, Royal Engineers, in 1908.     

INPUT OF PHOTOGRAMMETRIC DATA TO GEOGRAPHICAL INFORMATION SYSTEMS

Photogrammetric data form a major input to geographical information systems. The evolution of digital output from stereoplotters is traced, from hardwired devices producing co-ordinates or hardcopy to direct links with sophisticated GIS software. The view that the transfer and reformatting processes are simple and straightforward is examined and it is suggested that considerable labelling and structuring of data are necessary before the full power and flexibility of GISs can be harnessed. Hence it is argued that on line database creation by means of stereoplotter/GIS interfaces may not be the most cost effective procedure.     

Improving the image quality of spaceborne multiple-aperture SAR under minimization of sidelobe clutter and noise

As we know, a multiple-aperture radar carried by a group of formation-flying satellites can be used to improve the coverage and azimuth resolution of spaceborne synthetic aperture radar (SAR) simultaneously. However, in the case of the reconstruction of azimuth signal from a periodic nonuniform sampling sequence, the sidelobe clutter and noise may be amplified by tens of decibels in some cases, which makes the final SAR image blurry. In this letter, we present the analytical result of the amplification factor of sidelobe clutter and noise for the evaluation of the reconstruction performance. According to the result, we propose a method to reduce the sidelobe clutter and noise, which considerably improves the quality of SAR image. Computer simulation results confirm the effectiveness of the method.     

THE MAPPING OF NORTHERN GREENLAND

Approximately 110 sheets of orthophotomaps at a scale of 1:100000 covering all the ice, free area (300000 km²) of northern Greenland are to be produced by the Geodetic Institute of Denmark. Super-wide angle photography at a scale of 1:150 000 was acquired in 1978. Individual models are set up in a Wild B8S stereoplotter and, after carrying out aerial triangulation, a numerical method of absolute orientation is used. A digital ground model of the entire area is established in order to enable the interpolation of contour lines, for automatic plotting and to produce control data, for the orthophotoprojector. a Wild OR1. Methods of data handling and control, accuracies and typical errors are discussed.     

任意椭圆轨道下星载SAR多普勒参数的精确计算

国内外已有文献在推导星载SAR多普勒参数计算公式的过程中,均未考虑椭圆轨道下卫星航迹角不为零的影响,这使得已有公式只能近似地使用在近圆轨道上。如果用于大偏心率轨道,误差较大,将严重降低多普勒参数估计过程的收敛速度。为此,本文将航迹角的影响因素考虑在内,推导出可在任意偏心率轨道下使用的计算公式。针对小偏心率和大偏心率轨道,分别设计了一组仿真试验并进行了对比,结果表明:在大偏心率轨道下,航迹角对多普勒参数确有重要影响。     

组合图像模拟和精配准的星载SAR图像正射校正

本文给出了一种采用DEM模拟出的影像和星载合成孔径雷达(SAR)精配准策略的正射校正方法。首先根据DEM数据采用距离-多普勒模型和经验公式模拟出SAR图像,然后分别采用Harris算子和互信息匹配的方法提取模拟图像和实际SAR图像上的同名特征点,并根据这些特征点构建的不规则三角网(TIN)实现模拟SAR图像和实际SAR图像的精确配准。最后将星载SAR图像通过实际图像和模拟图像的精确配准关系以及模拟图像和DEM数据之间的对应关系校正到DEM所在的地理坐标中,实现SAR图像的正射校正。