The Use of Close Range Photogrammetry for Studying Ice Accretion on Aerofoil Sections

This paper describes the use of photogrammetry to measure and quantify ice accretion on an aerofoil section. A series of stereoscopic photographs was taken during the ice accretion on the section in an icing tunnel. From measurements made on these photographs with a Kern (Leica) DSR 14 analytical photogrammetric plotter, a series of three dimensional models of the ice surfaces was constructed. The results of the project are discussed and possible improvements in the methodology are suggested.     

Application of space borne cartographic camera for thematic mapping

A remote sensing experiment ‘TERRA’ was conducted during the first Indo-Soviet joint manned space flight. Under this experiment aerial photographs of the Indian terrain were taken using fixed cameras like MKF-6 and KATE-140 and hand held cameras like Hasselblad 500 EL/M and Practika B-200. In order to find out the positional accuracy of features identifiable on TERRA photographs, an experiment was carried out photogrammetrically using a stereopair of KATE-140 photographs. Analog as well as analytical stereo-plotter were used. A simple technique of comparing the known ground coordinates of various well defined ground features identifiable both on map as well as on stereo model, with the coordinate calculated from the stereopair observation was adopted. Due to the non availability of the actual coordinates of ground details/features and limitations of identifications of such ground details, used for observation in the present study, the results obtained have indicated that the residual errors are random in nature and not systematic. The results showed that such space borne aerial photographs like KATE-140, can be used for obtaining desired cartographic accuracy for the preparation of topographical as well as other thematic maps on scale 1:250,000 and smaller.     

ANALYTICAL AERIAL TRIANGULATION WITH ANGULAR MEASUREMENTS

In recent years interest has been increasing in the use of measurements from single photographs for analytical work. A monocular instrument based on the theodolite is described, together with preliminary test results.     

A PHOTOGRAMMETRIC SYSTEM FOR ARCHAEOLOGICAL MAPPING USING OBLIQUE NON-METRIC PHOTOGRAPHY

The Air Photographs Unit of the Royal Commission on the Historical Monuments of England (RCHM) has taken a large collection of oblique aerial photographs, using a non-metric camera, of archaeological evidence. Techniques are described which use this photography in conjunction with a Kern DSR1 analytical plotter to produce maps. Some results from using the techniques are given.     

A Cheap, Quick and Safe Way of Surveying Glaciers

The use of a 35 mm or similar camera set up over a theodolite is described for surveying mountain and polar glaciers where conditions do not allow for extensive detailed surveying or the use of heavy phototheodolites. Though used initially by Spender and Wright in the 1930s on Mount Everest and in Greenland and Arctic Canada, but apparently not by others since then, it was again tried out by Wright in Iceland in 1992. Modern analytical techniques have shown that heights accurate to within 2 m can be obtained from these photographs at distances up to 5 km. In addition, five times as many points can be identified and intersected in the laboratory from the photographs as was possible using sketches in difficult field conditions. Some reasons are suggested for the lack of use of this technique by others. The potential of existing survey photographs taken in Arctic Canada for large scale surveys of high polar glaciers in 1938 is described, with the hope that glaciologists and photogrammetrists might undertake their analysis.     

Digital Photogrammetry and Microscope Photographs

The feasibility of applying commercial digital photogrammetric software to the measurement of small objects photographed through an optical microscope has been examined. The objects, about 20 mm across, were photographed using a 35 mm film camera (at the lowest magnification setting of the Olympus microscope) giving photographs at a scale of 2:1. The photographs were then scanned before processing with the VirtuoZo digital photogrammetric system. Various problems needed to be overcome, some due to the limited options available with the highly automated digital system which was not designed for such measurement tasks. The unusual image scales, the uncommon pixel sizes and the unconventional and uncertain imaging geometry, all impeded immediate photogrammetric implementation. Photographic problems with the microscope were also faced, as with all microscope photogrammetry. Creating control points and independently assessing the accuracy of results at these scales were also difficult operations, but an analytical plotter was utilized for both these purposes and to verify the imaging geometry. Once such problems were overcome, image matching proceeded well and an accurate DTM could be created successfully, provided that a suitably textured object was chosen.     

DEVELOPMENT OF AN INEXPENSIVE IMAGE SPACE PLOTTER

This paper discusses an inexpensive, analytical system designed for a forestry application of photogrammetry. It is presented in two parts. Part I describes an image space plotter that was built in New Zealand and is operating there. The system uses a digitising table to collect left-hand photograph co-ordinates. an encoded micrometer bar to measure × parallax and a mirror stereoscope for viewing photographs. The mathematical, formulation is based on simplifications first suggested by E. H. Thompson. Good accuracy in ground heights can be achieved by the system, but only poor accuracy in planimetric co-ordinates. The cause of poor planimetric accuracy is investigated in Part II. Two error sources are apparent: the simplified analytical theory and systematic errors from the digitising table. Part II also investigates the relationship between random errors in image co-ordinate measurements and system accuracy.     

Analytical 3D views and virtual globes — scientific results in a familiar spatial context

In this paper we introduce analytical three-dimensional (3D) views as a means for effective and comprehensible information delivery, using virtual globes and the third dimension as an additional information carrier. Four case studies are presented, in which information extraction results from very high spatial resolution (VHSR) satellite images were conditioned and aggregated or disaggregated to regular spatial units. The case studies were embedded in the context of: (1) urban life quality assessment (Salzburg/Austria); (2) post-disaster assessment (Harare/Zimbabwe); (3) emergency response (Lukole/Tanzania); and (4) contingency planning (faked crisis scenario/Germany). The results are made available in different virtual globe environments, using the implemented contextual data (such as satellite imagery, aerial photographs, and auxiliary geodata) as valuable additional context information. Both day-to-day users and high-level decision makers are addressees of this tailored information product. The degree of abstraction required for understanding a complex analytical content is balanced with the ease and appeal by which the context is conveyed.     

测绘工程专业《摄影测量学》课程教育的实践与思考

摄影测量从产生到现在 ,已经经历了模拟摄影测量、解析摄影测量和数字摄影测量三个发展阶段。伴随着各种新兴的科学技术特别是计算机技术、空间技术和信息技术的迅猛发展 ,数字摄影测量在国内外已经进入了实用阶段。而目前 ,大多数高校测绘工程专业摄影测量学的教育教学工作没有及时反映摄影测量的最新进展 ,其教育教学和实习的重点依然是模拟和解析部分。本文主要探讨了当前测绘工程本科专业摄影测量教育教学体系中存在的几个典型问题 ,包括摄影测量学的教学目的、教学内容的整和优化和教材建设、教学形式与教学方法。同时结合了本人摄影测量学的教学实践 ,从实际出发 ,提出了解决这些问题的具体意见和建议 ,对摄影测量学的教学改革具有重要的指导意义和实践意义     

Helicopter Supported Photogrammetric Survey of Ramsberg Castle

Ramsberg Castle is to be restored and renovated to allow a new use of the building. This requires extensive structural and architectural analyses based upon metric documentation. The façades of the castle were recorded photogrammetrically. Photography from the ground was impossible due to the steep terrain on three sides of the building. For this reason, the photographs were taken from a helicopter. A 4 × 5 inch Linh of Metrika réseau camera was used.
Because of the adverse topography, only a few control points could be determined by on-site theodolite measurement. Therefore the control network was achieved by means of photogrammetric bundle triangulation. Stereorestitution was performed using an analytical plotter connected with a CAD system. Drawings at 1:50 scale were then derived from the as-built CAD model.     

Interpretation of an apollo space photo for small scale soil mapping in respect of an area in bihar

A section of an Apollo space photo relating to the Magadh area of Bihar state was monoscopically interpreted resulting in six delineations based upon tone and texture variations. Small scale aerial photographs were used for the preparation of soil map of a part of the area using a systematic air photointerpretation procedure; this served as a basis for defining the soil composition of four out of the six space photo analytical units. In respect of the remaining two units-soil information was obtained by reference to an existing small seale soil map of Bihar State. The data thus obtained have been used to prepare a small scale soil map of the selected section of the Apollo space photo. The soil map of the part of the space photo area that is based on support ph: to-interpretation has been found to have the quality and accuracy expected of very small scale soil maps.     

GCP collection for corona satellite photographs: Issues and methodology

Use of high-resolution and historic CORONA satellite photographs for mapping and other purposes requires Ground Control Points (GCPs), as ephemeris data and image parameters are not available. However, the alterations in landscape in last 34 years (i.e., since the acquisition of these photographs) prevent identification and collection of large number of GCPs in the field. This paper presents a methodology for collection of GCPs for CORONA photographs. The advantages and limitations of the methodology are discussed. For a study site, situated in Siwaliks and Lower Himalayas, the GCPs were identified in CORONA photographs and their WGS84 coordinates were estimated through a process of datum transformation and georeferencing. Estimated GCP coordinates from the topo sheets and 2D and 3D views of photographs, helped in identifying the GCP locations in field, which were observed using DGPS. Investigations were carried out to relate Differential Global Positioning System (DGPS) accuracy with base line length and time of observation. Abase line of 350 km and half an hour observation were found appropriate to yield accuracy in GCP collection by DGPS method, which conforms to CORONA resolution of 3 m.     

Residential area evaluation using GIS technique: A case study — Part of Bhubaneswar city

To evaluate a planning area or to implement plan procedures, planners need database in the form of land use, population density, housing density and point information regarding various facilities. At present planning tasks are carried out by manual methods where analytical capabilities are limited. Therefore, there is a need for reliable data as well as comprehensive database information indicating physical factors and good analytical tools. In a development plan various standards are specified in zoning regulations for the development of a city. To get an overall view, how these standards are implemented on the ground in planning period, a GIS application can be useful in analysing various amenity standards with respect to population and distances. In this study, for part of Bhubaneswar, basic data was generated from 1988 aerial photographs and other related information was gathered through field survey and secondary sources. The derived information in the form of a map has been entered into computer through digitization. Vector information was later converted into a raster form for the analysis. As per the planning standards catchment areas were created for limited facilities/services like schools, parks, play ground and accessibility to bus stop from main road. The population actually served by these facilities were calculated and compared with the existing planning standards. This particular study demonstrates the use of GIS in one of the planning tasks especially analyzing the residential areas as per the set standards such that improvement schemes can be proposed accordingly in the deficient areas.     

POPULATION CENSUS WITH THE AID OF AERIAL PHOTOGRAPHS: AN EXPERIMENT IN THE CITY OF LEEDS

This study shows how aerial photographs can be of value in a population census. The census and the enumeration district maps were used initially to obtain population data and the housing stock was derived from the aerial photographs. From these the population densities were determined of a number of sample enumeration districts containing a single type of house. Another set of enumeration districts was selected and the housing stock again derived from the aerial photographs. By considering the type and quantity of housing stock and the population density of each housing type, the population figures were estimated for each enumeration district. The values of these population estimates were then compared with the values recorded in the census. The overall population estimate had an error of only 2%, but the estimates for some of the individual enumeration districts showed greater errors. These errors are assessed and analysed and some suggestions are made to improve the methodology used in this study.     

Monitoring of salt affected soils — A case study using aerial photographs,salyut‐7 space photographs,and landsat TM data

Soils of part of Ukai‐kakarapar Command area, Gujarat (India) have been mapped at 1:25, 000 scale using aerial photographs of December 1977. It was observed that about 36.3% of the area was affected by soil salinity/alkalinity. The test area has been remapped using Salyut‐7 space photographs taken during Indo‐Soviet joint flight in April, 1984. The area affected by soil salinity/alkalinity was found to be substantially higher (80.3%). The earlier mapping using aerial photographs was done when the soil surface was compartively moist (December 1977) as compared to date of Salyut‐7 photography (April 1984), when the soil surface was likely to be devoid of moisture and the salts moved to the surface. To have easy comparision with the map prepared by using aerial photographs, Landsat TM data of December, 1985 was used in which 45.7% of the total area was mapped as salt affected. The extent of area delineated using Landsat TM was higher than that of 1977 but much lesser than the area delineated using Salyut‐7 (MKF‐6M) photographs. This indicated that the increase in the extent of salt affected area in the map prepared using the MKF‐6M photographs might be partly due to actual increase in the salinity/alkalinity and partly due to the seasonal affects. Among the various bands of MKF‐6M, band ‐4 was found to be the best for delineating the salt affected soils. The boundaries were sharper in the FCC and band No.4 of MKF‐6M than in the aerial photographs.     

Environmental evaluation of medchal taluk,Andhra Pradesh using aerial photographs

The human interaction with nature in the form of improper exploitation and unplanned utilisation of natural resources has caused a lot of environmental imbalance in nature. The aerial photographs and other repetitive orbital remote sensing data provide valuable information in identification and surveying of such environmentally imbalanced zones. In this study the aerial photographs were used in identifying such vulnerable areas and some remedial measures are suggested for the planned exploitation of natural resources without damaging the environment.     

DATA PROCESSING METHODS FOR AMATEUR PHOTOGRAPHS

Using modern techniques, the analysis of amateur photographs yields results with almost the same accuracy level as with metric photographs. This paper gives a classification of data processing techniques for amateur photographs and presents a well proven method for the treatment of existing amateur photographs, known as Metric Photo Perspective Transformation (MPPT). Data processing is particularly convenient and efficient if on line techniques are used. Operational procedures for the treatment of additional parameters and for the detection of blunders in a time critical on line triangulation system are proposed.     

Aerial survey for archaeology

Aerial photography for archaeology has been developing its approaches and techniques over the past 100 years so that it now integrates the results of reconnaissance with extensive interpretative and analytical surveys. This paper introduces the philosophy and approach of the English Heritage (EH) Aerial Survey team, covering aerial reconnaissance and the National Mapping Programme (NMP), as well as the potential developments and opportunities in Europe. In the 1980s there was a debate over the nature of the evidence derived from aerial photographs, especially how to describe archaeological features. As part of NMP a classification and recording system has been devised which meets most of the users' needs, be they national organisations, county archaeologists, commercial contractors or university-based researchers. The maps and records produced by NMP are used to further our understanding of the past human settlement in England, not only at the individual site level, but also in regional or landscape contexts. This paper provides an overview of the current progress of NMP and acts as an entrée for explaining the current research and recording of archaeological landscapes throughout Europe. Recent developments in Britain and Europe have provided the opportunity for a greater priority to be given to aerial survey and accelerating programmes of mapping. In Europe the ending of the cold war has allowed greater access to aerial photographs and the possibility of beginning new reconnaissance, as well as introducing new forms of remote sensing. All these developments have led to a transformation of our understanding of prehistoric, Roman and medieval archaeology.     

基于普通数码像片的相关系数影像匹配方法探讨

普通数码相机是非量测相机,所获取的像片属于近景像片,但像片没有已知的内方位元素且影像变形大,因此普通数码像片的图像处理比较特殊。针对普通数码像片特点及相关系数计算量大的特点,本文根据试验提出了一种匹配的准确率高、速度快的改进的相关系数匹配方法。试验表明该匹配方法在影像变形较大的情况下有较快的匹配速度和较高的准确度。