THE USE OF PHOTOGRAPHIC METHODS FOR TRAFFIC DATA COLLECTION

Several problems are encountered when collecting traffic information by conventional methods and which leave scope for the development of more comprehensive techniques. This paper reviews the potential of different types of photography as an effective means of obtaining comprehensive traffic information. Comparisons between conventional methods and photographic methods are made. The different types of available photography are discussed, together with their uses in the field of traffic data acquisition. Finally, the paper assesses the use of automatic and semiautomatic methods of photographic data analysis in this context.     

网络RTK技术在像控测量中的应用研究

分析了常规RTK在像控测量中的不足和网络RTK技术的优点,并在常州市航测项目中采用了网络RTK技术进行像控测量,实现了网络RTK技术在像控测量领域的研究和推广应用。     

THE GEODIMETER: AN INSTRUMENT FOR THE ACCURATE MEASUREMENT OF DISTANCES BY HIGH-FREQUENCY LIGHT VARIATIONS

Abstract

During the last few years a method of measuring accurately the lengths of lines of moderate length by means of high-frequency variations in the intensity of light emitted by a special transmitter, which promises to have many important applications in triangulation and precise traversing, has been devised by Mr. E. Bergstrand, of the Geographical Survey of Sweden. In principle, the method has certain resemblances to the apparatus invented and used by Fizeau for measuring the velocity of light, Bergstrand's instrument having been designed in the first place for the measurement of the same constant. In Fizeau's apparatus, it will be remembered, a ray of light was directed through the cogs of a revolving toothed wheel towards a distant mirror, and, when the wheel reached a certain angular velocity, the ray reflected from the mirror was intercepted by the cogs, so that an observer stationed on the same side of the wheel as the light source no longer saw the reflection of the light in the mirror. The angular velocity of the wheel being known or observed, the time taken for the cogs to obliterate the reflected image could be calculated, and twice the distance to the mirror divided by this time gave the velocity of light. In the Bergstrand apparatus, which is called the “geodimeter”, light pulses of known frequency and varying intensity are directed to the end station of the line whose distance is required, and, after reflection by a mirror at that station, are received back in a special receiving apparatus alongside the transmitter. Here they are converted into small electric currents, which, when the required distance is a certain function of the wave length of the transmitted and reflected pulses, can be made to give zero deflection on a sensitive galvanometer. In this way, the distance to be measured can be determined in terms of the wave length of the pulses. Experiments so far carried out with this apparatus have been successful up to distances of about 36 kilometres. Even with the latest model, however, as we shall see later, it is necessary to know the approximate distance to within 1½ km.     

THE GEODIMETER: AN INSTRUMENT FOR THE ACCURATE MEASUREMENT OF DISTANCES BY HIGH-FREQUENCY LIGHT VARIATIONS

Abstract

The constant K in equation (12) represents distance expended through time lags in the instrument itself, and, although the value of K can be calculated from electrical data, this would not be very satisfactory and it would be better to determine it directly by means of observations over a line of known length. In addition, the point from which K would be reckoned is not a convenient one for actual field measurements. Instead of this, it is more convenient to choose an index mark on the instrument itself and referall measurements to this and thence to the mark over which the instrument is set up.     

利用时空内插及数据正规化辅助方法监测地震前热异常

应用卫星热红外遥感图像提取震前温度变化信息,会碰到云干扰以及信息提取方法的科学性等课题.为了减少云干扰,本研究使用时空内插法来填补或复原受云影响的网格温度; 为了客观监测及记录增温现象,研究设定正规化标准值与阀值,使计算机半自动监测相对高温区,并利用不同时期图像云影移动及影像镶嵌技术,还原被云遮蔽的增温区,以期能科学反映地热异常现象,利于后续震前增温异常前兆研究的进行.     

南方NGS200应用实践中的若干问题

对南方NGS200在工程控制测量领域应用实践中的一些问题作了阐述，提出了一些见解和措施。     

THE APPLICATION OF RADAR TO SURVEYING

Abstract

Radar can be applied to surveying for precise measuren1ent of long lines, and as a navigational aid and position-fixing device for an aircraft performing a photographic survey. Trials of the radar method have recently been carried out in Australia using a modified “Shoran” equipment. The results of a large number of radar measurements of six distances, varying from 160 to 310 miles in length, indicate that an accuracy of 7 parts in 10⁵ can be achieved. Equipment errors constitute the immediate limit to accuracy, but reasonable modifications would yield a figure of 2 parts in 10⁵. Radar measurements can be completed in a fraction of the time required by normal ground survey methods, since a measurement of upwards of a hundred miles is made in a single step.

As an aid to photographic surveying a straight-line track indicator actuated by data from the “Shoran” equipment has been designed and flight tested. Its performance enabled a pilot taking aerial photographs to keep the aircraft to within an average departure of less than 0.02 mile from any desired straight-line flight path.     

变形监测中几个涉及测距问题的探讨

本文以平面位移监测为背景，阐述了边长前方交会法精度中的一个歧意，介绍了测距气象改正数的补偿计算方法，以及为便于比较各期距离观测值的变化而设计的仪器定高器．该文对高精度测距工作具有一定的参考价值。     

基于GeoServer的WebGIS在旅游服务中的应用

建立了基于OpenGIS的生态旅游自助服务系统网站,为旅游产业的各方提供一个信息共享的平台,促进居民参与旅游业的发展,将GIS与旅游业相结合,实现直观的、可视化的地理信息展示和管理.对生态旅游系统进行了目标分析,详述了系统的整体结构、功能模块和数据流程.服务器操作系统使用RedHat Linux Enterprise AS5; 客户机端使用主流的浏览器; 数据库管理系统采用PostgreSQL 8.0; 空间数据引擎采用PostGIS; 应用服务器平台采用 Tomcat 5.5 ; WebGIS平台采用GeoServer 1.5.3服务器,内置了GeoTools组件.以珠峰自然保护区为例进行了试验.     

THE METHOD OF SYSTEMATIC RELAXATION APPLIED TO SURVEY PROBLEMS

Abstract

This paper reviews and elaborates the application of the “Method of Systematic Relaxation of Constraints”, originally devised by R. V. Southwell for the calculation of the forces in frameworks, to the problem of the adjustment of survey networks to conform to the condition of least squares. The method is illustrated by the solution of a simple example of a triangulation network, and its application to larger surveys is discussed.     

THE APPLICATION OF THE PROGRAMMABLE CALCULATOR TO NUMERICAL ORIENTATION

The author shows that it is possible to carry out a rigorous least squares numerical orientation procedure on a programmable calculator. An iterative technique is adopted which reduces the rotational parameters to zero.     

数字专题信息在城市园林绿化中的应用

根据绿色植被在彩红外航空影像中的波谱特征，在惠州市申报国家园林城市项目中，制作1：5000彩红外数字正射影像图，在数字测绘产品的基础上提取了园林绿化专题信息，编制惠州市区园林绿化覆盖平面图，并对各类园林绿化覆盖进行面积量算，描述了数字专题信息在城市园林绿化中的应用。     

DEM数据在青藏高原地貌研究中的应用

近年来,青藏高原一直是国际及国内地质学界极其关注的地区.随着遥感技术的发展,基于DEM的地表过程分析给青藏高原研究带来了崭新的思路和方法.本文回顾了应用DEM数据进行青藏高原地貌研究的历史,通过分析其应用研究的几个阶段,总结了DEM技术在高原上的研究技术,阐述了DEM数据在各学科中的交叉应用,指出研究方法上的系统化、信息的进一步挖掘和高精度数据源获取是该领域发展的主要任务,并展望了DEM在地貌研究中的发展方向.     

多源信息在岷山地区遥感图像分类中的应用

采用了专家分类方法，将数字高程模型和由其生成的坡向信息与遥感图像的光谱信息相结合，提高了对土地利用的遥感图像分类精度。