Surfaces from the Visual Past: Recovering High<Emphasis Type="Bold">-</Emphasis>Resolution Terrain Data from Historic Aerial Imagery for Multitemporal Landscape Analysis

Historic aerial images are invaluable sources of aid to archaeological research. Often collected with large-format photogrammetric quality cameras, these images are potential archives of multidimensional data that can be used to recover information about historic landscapes that have been lost to modern development. However, a lack of camera information for many historic images coupled with physical degradation of their media has often made it difficult to compute geometrically rigorous 3D content from such imagery. While advances in photogrammetry and computer vision over the last two decades have made possible the extraction of accurate and detailed 3D topographical data from high-quality digital images emanating from uncalibrated or unknown cameras, the target source material for these algorithms is normally digital content and thus not negatively affected by the passage of time. In this paper, we present refinements to a computer vision-based workflow for the extraction of 3D data from historic aerial imagery, using readily available software, specific image preprocessing techniques and in-field measurement observations to mitigate some shortcomings of archival imagery and improve extraction of historical digital elevation models (hDEMs) for use in landscape archaeological research. We apply the developed method to a series of historic image sets and modern topographic data covering a period of over 70 years in western Sicily (Italy) and evaluate the outcome. The resulting series of hDEMs form a temporal data stack which is compared with modern high-resolution terrain data using a geomorphic change detection approach, providing a quantification of landscape change through time in extent and depth, and the impact of this change on archaeological resources.     

Computer Simulation in Population Geography

Two concepts of models in geography are distinguished: one is a model in the form of an equation or system of equations; the other is a computer program that uses a simulation algorithm. The paper deals with the computer simulation aspect, distinguishing four levels of machine modeling: (1) programs for the methods of analysis generally used in geography, particularly, correlation and regression analysis; (2) programs for the analysis of settlement maps; (3) computer simulation of complex processes, such as R. L. Morrill's model of town growth in southern Sweden, using Monte Carlo simulation; (4) the use of computers in the analysis of theoretical problems, illustrated by R. S. Yuill's study of diffusion waves, also using the Monte Carlo method.     

Mapping by matching: a computer vision-based approach to fast and accurate georeferencing of archaeological aerial photographs

To date, aerial archaeologists generally apply simple rectification procedures or more expensive and time-consuming orthorectification algorithms to correct their aerial photographs in varying degrees for geometrical deformations induced by the topographical relief, the tilt of the camera axis and the distortion of the optics. Irrespective of the method applied, the georeferencing of the images is commonly determined with ground control points, whose measurement and identification is a time-consuming operation and often limits certain images from being accurately georeferenced. Moreover, specialised software, certain photogrammetric skills, and experience are required. Thanks to the recent advances in the fields of computer vision and photogrammetry as well as the improvements in processing power, it is currently possible to generate orthophotos of large, almost randomly collected aerial photographs in a straightforward and nearly automatic way. This paper presents a computer vision-based approach that is complemented by proven photogrammetric principles to generate orthophotos from a range of uncalibrated oblique and vertical aerial frame images. In a first phase, the method uses algorithms that automatically compute the viewpoint of each photograph as well as a sparse 3D geometric representation of the scene that is imaged. Afterwards, dense reconstruction algorithms are applied to yield a three-dimensional surface model. After georeferencing this model, it can be used to create any kind of orthophoto out of the initial aerial views. To prove the benefits of this approach in comparison to the most common ways of georeferencing aerial imagery, several archaeological case studies are presented. Not only will they showcase the easy workflow and accuracy of the results, but they will also prove that this approach moves beyond current restrictions due to its applicability to datasets that were previously thought to be unsuited for convenient georeferencing.     

Streams,Slopes, and Suburban Development

The percent of available relief in the form of free-face slope and the percent of valley width as floodplain change systematically throughout drainage networks in response to changes in network position. The energy level and discharge of streams at the bases of slopes may be assessed by means of a cumulative stream-ordering system wherein the stream order is directly related to discharge. Investigations of several small drainage basins on the rim of the Denver Basin, Colorado, by means of field measurements, interpretation of aerial photography, and operation of a computer model provide data that indicate that the distribution of near-channel slopes responds to changes in land use, and particularly to suburban development. Increasing suburban development causes increases in the size and frequency of both free faces and floodplains.     

COMPUTER VISION‐BASED ORTHOPHOTO MAPPING OF COMPLEX ARCHAEOLOGICAL SITES: THE ANCIENT QUARRY OF PITARANHA (PORTUGAL–SPAIN)

Ancient quarries are intriguing archaeological sites, but their detailed recording is complex. This paper presents a cost‐effective approach to mapping of the Roman quarry site of Pitaranha (Portugal–Spain). First, aerial photographs were acquired using a radio‐controlled digital reflex camera attached to a Helikite, which allowed the acquisition of the necessary low‐altitude aerial footage in the very unstable wind conditions above the quarry. Using computer vision algorithms, the resulting set of photographs was semi‐automatically transformed into a Digital Surface Model (DSM) and a corresponding orthophotograph. Besides focusing on the acquisition and processing method, this paper evaluates the accuracy of the generated products. The orthophotograph proved to be satisfactorily accurate for 1:200 hard‐copy mapping.     

The militarisation of aerial theatre: air displays and airmindedness in Britain and Australia between the world wars

ABSTRACT

Aerial theatre, the use of aviation spectacle to project images of future warfare, national power and technological prowess, was a key method for creating an airminded public in the early twentieth century. The most significant and influential form of aerial theatre in interwar Britain was the Royal Air Force Display at Hendon, in which military aircraft put on impressive flying performances before large crowds, including an elaborate set-piece acting out a battle scenario with an imaginary enemy. Hendon was emulated by other air displays in Britain and in Australia, even civilian ones. Indeed, the inability of the much smaller Royal Australian Air Force to regularly project spectacle on the scale of Hendon across a much larger nation created a gap which civilian aviation organisations then tried to fill. Hendon thus helped to propagate a militarised civilian aerial theatre, and hence airmindedness, in both Britain and Australia.     

Computer analysis of an inconsistent data source: the case of probate inventories

Computers are becoming increasingly popular for analysing data in historical geography and are being applied to an extending range and variety of historical sources. The methods described in most computer texts for geographers and historians, using the langueage allied to punched cards, are only suitable for numeric data which are in a standardized and consistent form. Rather than attempting to apply these methods to sources not organized in this way, it is more sensible to tailor a technique to a particular class of data.This paper considers some advantages of computer analysis, using English probate inventories as an example. Limitations of conventional methods are discussed and a technique is described for dealing with sources whose information is inconsistent between records. The method relates the logical structure of inventories to the storage and use of data by the computer, and considers the forms data can take for input to the machine. An example from the analysis of inventory data prepared by this method is briefly presented, describing two aspects of agricultural change in East Anglia between 1580 and 1740.     

Rent-Commuting Cost Function Versus Rent-Distance Function

This paper develops a new way to present standard urban models graphically and a new rent function called the rent-commuting cost function. The rent-commuting cost function represents the relationship between rent and total commuting cost. At least theoretically, it is superior to the traditional rent-distance function in depicting and measuring stylized facts of the city because its gradient is independent of the functional form of the commuting cost function and falls as household income rises.     

Drones: disembodied aerial warfare and the unarticulated threat

The Obama administration's controversial use of drones in Afghanistan, Pakistan and Yemen has made the subject a hot topic of political and academic discourse. While most of this debate has focused so far on the legal, ethical and prudential use of large armed aerial vehicles, this article seeks to address the potential wider impact of this new technological innovation. The article argues that drones constitute a new and disruptive technology not just in the way that they have been used to enable a new form of counterterrorism. Instead, it argues that drones pose a new form of terrorist threat against the West which is at present under‐analysed, unarticulated and underestimated. Part of the reason for this underestimation is the failure to appreciate the scale and scope of drone use for commercial purposes which is about to unfold. Technological innovation now means that drones will be capable of many jobs currently performed by small planes and helicopters, but more cheaply and easily—in addition to many other new applications. The proliferation of this cheap and easily available technology will make its application for terrorist use easy to achieve and difficult to counter. The ability of drones to penetrate traditional defences and established conceptions of what constitutes a plausible threat is a challenge which so far has gone unheeded. This article seeks to challenge that complacency.     

Bits,bytes and the Byzantinist: databases reviewed

Abstract

A computer is a machine which can receive, store, manipulate and yield up information. The use of computers can be traced back to c.1812 when Charles Babbage conceived his first main idea for automatic computation, but it is clear that development has been rapid and widespread especially in the last 20 years. Computers were originally developed for performing numerical calculations. However, although most forms of information can be translated into numbers, it is important to realise that computing today is no longer confined to numerical work. One of the most interesting and significant developments of the use of computers to research and teaching in the humanities is the growing body of material which has been put into machine-readable form. For example, censuses, parish registers, wills and accounts have been input to a computer, increasingly in the form of a structured database.     

Effective hydration temperature of obsidian: a diffusion theory analysis of time-dependent hydration rates

An estimate of effective hydration temperature (EHT) is needed for chronological use of obsidian hydration data. This paper describes a method for calculating EHT by the practicing archaeologist, replacing three techniques that are in general use today: estimates based on mean temperature, numerical integration of models of diurnal and annual temperature variations, and use of temperature cells. The hydration (or diffusion) coefficient of obsidian is a function of temperature and thus is time varying, while the classic quadratic law of hydration is not valid for time-varying diffusion coefficients. This paper presents a mathematical solution to the case of a time-varying hydration coefficient, based on diffusion theory, with a concise definition of EHT. It is shown that the results are not affected by concentration dependence in the diffusion coefficient. A computer program to compute the rigorous solution is described, and data are presented to explore the resulting range of variation. That use of the Lee equation to compute EHT is not appropriate for obsidian hydration studies is evident from the data presented. The effects of paleoclimatic variation are estimated, and an algebraic best fit equation and worksheet are provided as practical aids to the archaeologist.     

PORE-SIZE DISTRIBUTION DETERMINATIONS IN NEOLITHIC,IRON AGE,ROMAN AND OTHER POTTERY

A method of evaluating the pore-size distribution of pottery is described and results obtained from a number of samples ranging from Neolithic to modern pottery shown graphically. The method may serve to distinguish between similar-looking sherds if no other means of identification exists, but further work is needed before a series of determining curves can be established.     

建设古籍注释研究理论框架的重要意义

根据古籍注释研究的现状,目前应重点加强立足于未来机器整理古籍层面上的注释理论研究及其可操作程序的研制工作,从注释的理据、作法的原则、使用的方法、注释批评的标准、注释术语的规范等方面入手,建设古籍注释学学科体系的理论模式,以利于国家古籍整理事业的蓬勃发展。     

Numerical Analysis,Computers and Problem-solving

Abstract

The number of problem which can be solved by the method of classical mathematics is limited, especially those which have application to practical problems. Numerical analysis offers a way out, but demand the co-operation of scientist, applied mathematician, and expertise in computer software and numerical methods. The following article discusses examples amenable to numerical analysis and describes the Oxford University-Industry Study Group which has successfully contributed to the solution of applied problems. It also argues for the establishment of computer program libraries which have recently become a valuable adjunct to problem solving.     

Method for photogrammetric surveying of archaeological sites with light aerial platforms

In this paper, we describe a complete methodology for performing photogrammetric surveying of archaeological sites using light aerial platforms or unmanned aerial vehicle (UAV) systems. Traditionally, the main problem with using these platforms is the irregular geometry of the photographs obtained. These irregular image block patterns are occasioned by uncontrolled circumstances (e. g. effect of wind, lack of flight control, etc.) which generate high imprecision in the positioning of camera stations. The method proposed here allows the execution of the photogrammetric flight following the predicted parameters determined in mission planning (camera focal length, photo scale, ground sample distance -GSD-, overlaps, etc.) so we can obtain regular flight geometries. Our method allows the use of conventional photogrammetric data reduction methods based on the use of stereoscopic photogrammetric workstations. Although flights with irregular patterns can allow the formation of stereo pairs within certain limits, conventional photogrammetric procedures often have great difficulty in processing these irregular image blocks. For this reason this system raises the staking out of the camera positions by using a robotized total station and a mini prism situated on the platform. This method is applied to a real photogrammetric survey of an archaeological site of the Tartessic epoch in Southern Spain. The results obtained, confirmed by a quality control of the photogrammetric flight, have demonstrated the viability of this methodology even when moderate wind effects appear.     

Frequency table analysis: Examples from early bronze age axe decoration

This paper describes the use of log—linear models for the analysis of frequency tables and also introduces an alternative technique, “iterative proportional scaling” (IPS). The log—linear approach is illustrated using data on the reliability of reported decoration in a set of Early Bronze Age axes from southern Britain. The method, as implemented in the computer package GLIM, is then applied to data on the decoration of the faces and sides of those axes, divided into two chronological phases to form a three-dimensional table. The same table is analysed using IPS, and the relative advantages and the applicability of the two methods are discussed. The appendices give some practical information on the availability of programs and the computational steps involved in IPS.     

Package FLUIDS. Part 3: correlations between equations of state, thermodynamics and fluid inclusions

The computer package FLUIDS ( Bakker 2003 ) has been revised to calculate fluid properties in pores and inclusions. The programs are provided with a Graphical User Interface (GUI) and are adapted to new operating systems, including MacOS, Windows and Linux. The van der Waals equation of state has been added to the group Loners and is used to illustrate a large variety of calculation procedures for many thermodynamic parameters and properties. The mathematical transformations can be applied to any equation of state with the form p ( V , T , n ), i.e. the pressure of a multi-component fluid is expressed as a function of volume, temperature and amount of substance. The fluid properties that are usually observed in microthermometric analyses of fluid inclusions, such as phase separation, phase coexistence and stability, can be predicted with these equations of state by using its spinodal and critical point calculations, in addition to fugacity calculations of liquid and vapour phases. The computer program LonerW can be freely downloaded from the website: http://fluids.unileoben.ac.at/Computer.html .     

Comparison of Plane Forms

Nonlinear two-dimensional grid transformations are used to compare plane figures. The method is based on the identification of homologous points, and thus can be considered as a bidimensional extension of ordinary curvilinear regression, but is here approached from the point of view of cartography. All of the techniques illustrated by Thompson in 1917 can be mimicked by the computer program. Extensions of the method, based on the derivatives of the transformations, permit the determination of the axes of principal change, and also suggest numerical measures for the degree of similarity of topologically equivalent figures. Applications are illustrated in biology and geography, and more general uses are suggested.     

浅谈初中信息技术课教学模式和方法

初中计算机教学主要目的是激发学生学习和使用计算机的兴趣,巩固学生学习计算机的热情,让学生初步掌握计算机的基本操作技能并应用于实践,注重培养学生的信息素质和创新思维以及自学能力,为达此目的在教学中应根据学生实况采取灵活多样的教学模式和方法。