摄影测量学毕设论文外文翻译翻译+原文.doc

Photogrammetry
The principles of photogrametry can be traced back to the works of Leonardo da Vinci in the late fifteenth century. Through his work in the fields of geometry, optics, mechanics, and geophysiscs, da Vinci graphically illustrated the concepts of aerodynamics and optical projectio It is not until the mid 1800s that the field of photogrammetry came into its own, particularly within the European community. The term photogrammetry was first coined in 1855 by the European geographer Kersten, and was in common use throughout Europe by 1900.The term, however, did not win wide acceptance in the United States until 1934.In that year, the American
Society of Photogrammetry (ASP) was founded.
Types of Photogrammetry The ASP currently consider photogrammetry to be the art, science, and technology of surveying and measuring by photographic and other energy-emitting processes. The procedure is extensively used in topographic mapping, and can be applied from t ground as well as in the air. Aerial photogrammetry, though, is the procedure most commonly used in mapping. It has all but eliminated the need for extensive field surveys. Ground, or terrest photogrammetry is used only as a supplement and complement to the aerial process, or in areas with unusual physical characteristics.
Like other professional disciplines, photogrammetry consists of a variety of specialty area
For example, there are the two broad areas if terrestrial (ground) and aerial (air) photogrammet Other specialty areas of photogrammetry are defined as to the technology or energyemitting process used. Some of the types of photogrammetry used in the mapping and topographic field are discussed here.
Radargrammetry is the use of radar as a measuring device to describe the physical characteristic of an area of the earth’s surface. X-ray photogrammetry employ X-ray to collect surveying data, and the use of motion pictures for surveying is called cinephotogrammetry.
Hologrammetry is the use of holographs images projected by the use of coherent light systems such as lasers to measure surface characteristics. In monoscopic photogrammetry, single images or photographs are use or surveying purposes. Finally there is space or satellite photogrammetry, in which spacecraft or satellites are utilized as utilized as a platform for ta surface measurements. This type is also referred to as extraterrestrial photogrammetry.
Aerial Photography: The aerial photograph is perhaps the most familiar product of the photogrammetry field. It application in the mapping and topographic dada collection process combines the use of scientific and artistic procedures and techniques. Aerial photogrammetry, the is the use of photographic images taken from an airborne base for surveying purpose.
The success and accuracy of an aerial photography mission is dependent upon a number of important factors , including the following:
1. The use of correct photographic equipment, lenses, and supplies;
2. Appropriate correct photographic materials, such as film, print and duplication materialreflection print materials, and plates;
3. The photographic team (pilot, photographer, and film processor ) ;
4. Weather conditions;
5. The position of the sun when the photographs are taken.
Classifications of Aerial Photography Aerial photography is a complex and dynamic profession, as is the photogram metric field in general. Aerial photography requires a vast array equipment, technologies, and procedures. Therefore, to classify the various types of aerial photographs used in the mapping and topographic field, The ASP has identified four criteria: th orientation of the camera axis, the tens systems, the spectral range, and the mode of scanning th criteria are discussed in this section.
Orientation of Camera Axis This refers to the angle at which the camera is in tentionally positioned at the time of the photograph. Ad shown in fig.23-1, these are two orientations of ax used in aerial photography. These are the vertical orientation axis and the oblique orientation a
With a vertical orientation axis, the photograph is taken when the camera is intentionally positioned as nearly vertical-or as close to 90° to the earth’s surface-as possible. Because of the earth’s curvature and aeronautical factors, it is impossible to obtain a true theoretical vertical picture (hence the qualifier “as nearly vertical as possible”). For practical mapping purposes, however, the “near vertical” is more than sufficient.
The vertical orientation axis is the most common type of aerial photograph used in mapping. This type of photograph cam be easily converted into map drawings: it fives a sense of an ex fisting map or chart. The three major advantages of using the vertical orientation axis are that measurements can be easily taken off the photograph and transferred, surface objects and
landmarks can be easily identifies, and the amount of hidden ground (areas not observable in th photograph) will be minimal.
Oblique orientation axis photographs are images intentionally registered off vertical, and the oblique, technically, this means that the camera lens angle is aimed between true horizont and vertical. These photographs can be further subclassified into high oblique and low oblique. high oblique photographs pertain to the optical axis of the camera being at a high angle to the vertical, while low-oblique photographs have the optical axis of the camera at a low angle to t vertical.
Oblique photographs have a limited application for mapping. They are only of practical use in situations requiring small-scale drawings. The two advantages of the oblique photographs ar
that they provide a stereoscopic or three-dimensional perception of the photographed area, and they can provide a larger area coverage than is provided by vertical photographs .there are, however, three significant disadvantages to using these photographs for map and topographic drawings. Fist, there is a loss of imagery and resolution. Second, the scale constantly reduce one observes images a way from the camera. Third disadvantage is that highly skilled personnel and specialized equipment are needed to generate an accurate and useful product, resulting in higher cost.
Lens Systems These are classified by the number and configuration of the camera lenses used for aerial photographs. Within this framework, all lens systems, and the multiple lens systems.
The single-lens system is the most popular and frequently used system in aerial photography. It is applicable for either vertical or oblique photographs. The single-lens system usually empl a 153 millimeter (mm) focal length with a 228×228 mm format , while using only one lens per shot. By comparison, super wide-angle lens cameras are seldom used. If used, however, it is fo photographic missions over low-relief terrain.
Multiple-lens systems consist of two or more lenses. These systems can be sub classified by the type of mounting used. The fist mounting is where the lenses are separately mounting in different cameras and the shutters are synchronized for simultaneous exposures. In each case, t lenses are fixed at different optical axes so that the photographs can be used on a stereoscope accuracy, and usefulness of photographs taken with a multiple-lens system are dependent upon the care and accuracy, of the calibration and retention of the axis angles.
Another term used for the multiple-lens system is multispectral systems consist of two or more cameras, simultaneous exposures of an area of land, and the choice of different films and/ filter combinations.
Spectral Range This criterion refers to the entire range of light on the spectrum. The vast majority, of aerial photograph is limited to the range of the spectrum that can be observed by
human eye. This is called the optical range .in some situations, aerial photographs are used to record images within the infrared range.
Spectral is measured in terms of micrometers (um). As shown in Fig.23-2, the optical range is from 0.4 um to 0.8um um, while the infrared range starts at 0.8 um. With the use of photographi film capable of recording optical range image, it is also possible to record some infrared imag the lower end of the scale (i.e., 0.8 um and 0.9 um). Photography further into the infrared ra requires the use of special film and procedures. Because infrared is used to photograph temperature difference, it is also referred to as thermal photography.
Mode of Scanning This is the last criterion used in classifying aerial photographs. There ar three scanning modes used in aerial photography: the single frame, panoramic and continuous strip. In this sense, scanning refers to how the camera lens functions during the photographic process.
Of the three scanning modes, the single-frame camera, the entire frame (format) is exposed through a lens that is fixed in relation to the focal plane. These cameras are the easiest to u the least expensive. They also provide the most accurate data to transfer onto maps and topographic drawings. There are, however, two disadvantages to single frame photographs. First, these is a resolution as one moves away from the center of the photography.
The problems associated with single frame photographs can be solved with the use of panoramic or continuous-strip cameras. Panoramic photography combines a high resolution at the center of the picture over the total angle scanned, which in some cases can be from horizon to horizon. Panoramic photography is accomplished by using narrow angles ,fast lens systems, by scanning the lens system though large angles across the flight path, and by using normal-width film and advancing it parallel to the scanning direction at ground speed.
Continuous-strip photography eliminates the need for a conventional shutter system. The
images are exposed on the film as the film passes continuously over a narrow slit in the focal plane of the lens at ground speed. Ideal for low-altitude reconnaissance photography, continuous-strip photographs provide a sharp picture scanned in one long strip.
Ground control points The application of ground control points is a system used to ensure the accuracy of aerial photograph interpretation ground control points represent a series of f references which establish positions and elevations, ground control points are also used for correlation various-map features. Control is classified into four orders which represent the deg of accuracy and precision. The first order signifies the highest degree of precision or quality.
The precision of the control system is based upon the use of the following seven types of controls.
1. Basic control is determined in the field and is permanently marked, or monumental. It ibased upon horizontal and vertical control of the third order or higher.
2. Horizontal control is control is control relative to positions referenced to geographic parallels and meridians; that is, references with horizontal positions only (e.g. latitude, longitude, or plane coordinate axis).
3. Vertical control is usually made in reference to sea level and ground elevation.
4. Astronomical control is control established by astronomical observation.
5. Geodetic control are those control that account for curvature of the earth’s surface.
6. Ground control is frequently associated with basic control and geodetic control. these areferences that have been established by ground or field surveys.
7. Supplemental control is made when additional, or subordinate, surveys are conducted to correlate the aerial photograph with geodetic control, thus ensuring positive identificatio ground features and monuments.
Applications of Aerial Photography To the casual observer, it may appear that aerial photography is only good for providing picture of the earth’s surface from an overhead perspecti Nothing could be further from the truth. There are a number of applications for aerial photograph in the mapping and topographic field. These applications are useful to people in various professions, including engineers, geologist, geographers, planners, city administrators, agricul specialists, lawyers, and economists. All applications, however, fall into four major categories. These are photo interpretation, stereo compilation, orthophotography, and analytical aero
triangulation.
Photointerpretation is a process used to analyze aerial photographs for the identification measurement of surface objects and features. When used in an engineering study, this process usually emphasizes the relationships between surface objects and features and the project itse Any person who is trained in photo interpretation can obtain a substantial amount of informatio when applied to specific professions, this information can mean the difference between financia success and failure.
Stereo compilation is the process of extracting information from a stereo model. A stereo model is a three-dimensional image or model that is formed when the projecting rays of an overlapping pair of photographs intersect. The three-dimensional model, then, is based upon th use of aerial photographs, taken at slightly different angles, of the same area of land.
The purpose of a srereocompilation is to extract precisely located feature information fro aerial photography. The stereo model created is characterized by vertical “stretching” or exaggeration that emphasizes the difference of contour features, and makes if easier to produc accurate map features. Hence, stereo compilation makes it possible to provide great accuracy o geodetic control data.
Orthophotography is the use of an aerial photograph as the final map product, It represents immensely useful substitute for small-scale maps. This process is widely used by geographers and by agencies such as the United States Geological Survey.
The process of orthophotography eliminates the need for transferring all measurements and information from the aerial photograph to a drawing. The map produced by orthophotography is called a photomap. The process begins with a perspective photograph. The displacements of all images due to tilt and relief are removed; this is known as differential rectification. Ail information not shown on the photomap, such as scale, names, and elevations, are either drawn, scribed, or overprinted during reproduction.
Analytical aero triangulationis a procedure required to supplement ground control points which are too far apart for photogram metric compilation needs. Analytical aero triangulation means that the coordinates of photo control points are produced by mathematical procedures rather than by analogue methods. This is a highly technical and analytic procedure used to establish precise photogram metric data.

摄影测量学
最早提出摄影测量学概念能够追溯到15世纪后期Lenarda da vinci著作中，不过他研究领域主要集中在几何学、光学、物理学及地球物理学，所以他主要从空间动力学和光学投影方面阐述摄影测量概念。直到19世纪摄影测量学才真正形成，尤其在欧洲学术界重视下，摄影测量学逐步兴起。