نشریه اطلاعات جغرافیایی (سپهر)
پیاپی 59 (پاییز 1385)

Information systems have been created for certain purposes, so they must first fulfil specific mission and tasks, and then be able to support real affairs. In this paper, we will attempt to propose reasons to support the notion that GIS should not be considered as an exception among information systems, and to explain how geographic information can be re-used.

The Persian Gulf has a prominent geographic position. Natural conditions such as little depth, water salinity and high evaporation on the one hand, and limited communication with open lands of the world on the other, have created a special ecosystem within the Persian Gulf and its coasts. The Persian Gulf has long been regarded as one of the most important strategic regions of the world. The Persian Gulf region is a geopolitical unit located in the wider geostrategic basins of the Indian Ocean. The geographic region of the Persian Gulf acts as one of the most active economic centers in the world. It’s major exports are oil and gas and it’s imports mainly consist of industrial and food products. Natural potential and vast oil and gas resources have contributed to the establishment of a single-product economic system in coastal countries.

Given that cities are carriers of culture, derived from nature and reflecting the spectrum of our social goals, technology, values ​​and institutions, they are considered as significant subjects of study for cultural geographers as they provide the scholar with a deep insight into human mosaics. City is considered a cultural phenomenon and therefore it should be viewed from the point of view of cultural geography. Cultural geography, which is considered by some thinkers as including social and economic geography, is a worthwhile view that can help examine some of the social, economic and physical qualities and effects of the city. Cultural geography covers the study of spatial changes of cultural groups and spatial functions of society, and relies on description and analysis of differences and similarities in language, religion, economics, government and other cultural phenomena from place to place. Given that cultures are formed by human groups, cultural geography, therefore, necessarily involves humans in aggregate. In this paper, we try to investigate the internal structure of city with emphasis on some of the well-known concepts of cultural geography perspective, such as urban cultural areas, cultural broadcasting and cultural perspective of the city.

One of the main tasks of spatial information systems such as GIS is the aggregation of various data sets and their preparation for communication and analysis in various applications. The aggregation of data in spatial information systems requires collection of different types of data drawn from multiple sources, which would in turn necessitate complete alignment among these data sets and the similarity of features and phenomena in them. For example, it is possible that spatial information be extracted in several forms and from several sources, that is, the GIS data sources can be maps from land surveying, photogrammetry and remote sensing on different scales or with different resolution or at different times. In addition, there is a risk of data being obtained in ways that are incompatible and different in terms of validity. Some details may also be omitted or not defined. The incompatibility among various data is likely to come from an incompatibility among spatial information of the data recorded, including differences in dimensions (size), shape, composition, position accuracy or orientation.

The expansion of cities and urbanization and the gradual increase of the number of large cities in the world especially in developing countries including Iran on the one hand, and the growth of cities, concentration and accumulation of population, and increase of environmental and economic load on them on the other, have led, in addition to greater attention paid to cities, to the acceptance of numerous roles and functions by them. One of the issues that most of the big cities in the world are concerned with is natural disasters. The unpredictability inherent in most of natural disasters and the need for rapid and correct decision-making and implementation of the operation in their face have created the theoretical and fundamental foundations of a science named Crisis Management. This science refers to a set of activities that take place before, during and after the crisis to reduce the effects of these incidents and decrease vulnerability. This has a special relationship with geography and urban planning and management. By using the principles and regulations of urban planning and by clarifying the concepts of this science such as the form, texture and structure of cities, urban land use, communication networks, urban infrastructure, etc., we can greatly reduce the effects and consequences of natural disasters. The geographic extent of Iran is one of the most vulnerable parts of the Planet in terms of the probability of occurrence of these events, especially earthquakes. Every year the occurrence of these incidents causes a great deal of life and financial losses, and urban areas have always had a bitter experience of the occurrence of such disasters. It seems therefore to be necessary to carry out specific planning for the safety of urban spaces. Cities are severely damaged by such cases due to population concentration and economic investment in them. Since the beginning of their formation, they have chosen a particular form and structure for their growth and have expanded over time. The science of urbanization can reduce the effects of such disasters by explaining its principles and concepts and by relying on geographical data, and crisis management can use these data to implement the necessary management principles to reduce the vulnerability of cities to these events.

Understanding natural issues and the way natural phenomena operate, whether in order to enjoy their benefits or to deal with their adverse effects, must be accompanied by observation and interpretation of phenomena. Proper interpretation and accurate analysis of the results of observations requires necessary and sufficient information concerning the events’ ways of occurring and the past history of phenomena. In natural problems such as landslides, earthquakes, etc., and in historical issues and requirements of humans such as nutrition, habitation, water pollution, etc., the instantaneous recognition or the course of changes in time as well as historical comparison of magnitude of changes are duly considered, and geographers can well examine this issue and consider, in their studies on large expanses of land, how short-term changes occur during the phenomenon, and, by referring to these changes, generalize the results to the future and predict the intensity and extent of future events. Thus it can be said that natural geography perceives the momentary balance of phenomena, or at least seeks to understand it, and even takes time backward or forward on a scale of human history. In other words, the present form of the Earth and the current conditions in any given phenomenon are of great concern to geographers, but accurate information from the past is always needed for their accurate examination. Furthermore, there is a need for predictions about the future trend based on current trends and past information when considering long-term exploitation of natural resources. According to the above-mentioned matters, it can be clearly stated that the study of changes in phenomena over time is the basis of geography studies, especially natural geography. Fortunately, today with the development of communications, it is possible to extend the scope of these studies to different spaces with various features, and also to collect more information; on the other hand, using new methods, techniques and facilities, the horizons of vision in the past, and in some cases in the future, have become more extensive.

The GPS / IMU hybrid system is widely used for accurate measurement of position and aerial imagery justification or other justification methods in recent years. In particular, with the advent of digital sensors, the introduction of this technology has been accelerating. However, some users of these systems face many problems in fully utilizing this technology. Most of these problems are not due to the failure of GPS / IMU system or problems encountered during flight operations, but due to the lack of proper understanding of position measurement and direct justification of photographs in photogrammetric operations. Particularly the use of the title Calibration may create ambiguity with regard to air sensors equipped with GPS / IMU systems. In this paper, various concepts of "Calibration" for the Camera / GPS / IMU system are discussed.

Human history, from distant past up to the present day, has always witnessed catastrophic natural disasters causing human casualties, financial losses and vast destruction. Geomorphologic hazards are among these phenomena and threaten the lives of millions of people (lives and property) on the planet. Their occurrence imposes massive losses on agricultural, livestock and industrial sectors. In fact, these hazards are natural phenomena, but they turn out disastrous when faced with human societies and lead to enormous life and financial losses (Fann Weston, 1998 and Alcantara Ayala, 2002) and become geomorphic disasters. Today, human beings have not had much success in improving living conditions and reducing destructive effects of disasters in spite of the existence of different sources and systems for obtaining ground data and converting this data into knowledge and making use of this knowledge. Of course, the solution to the problem should be sought in increasing the level of knowledge of human being. By correct management of different types of data and information and taking advantage of new technologies such as remote sensing, it is possible to some extent to reduce the aspects and intensity of damages caused by occurrence of geomorphologic disasters.

The intersection of Bafgh-Mashhad railway with Niganan basin is part of Iran's salt pan within the range of eastern longitudes of 57 to 58 degrees and 30 minutes, and northern latitudes of 33 degrees and 15 minutes to 34 degrees and 45 minutes. Since examination of safety methods of railway’s intersection with the mentioned basin is dependent on availability of basic information and maps with regard to natural phenomena, this paper attempts to explain the methods of preparing and evaluating different maps in relation to the subject, in such a way as to provide a proper and (as much as possible) accurate picture of the basin. Geographic information system software has been used to prepare, utilize, combine and process maps, which will be referred to in the text. In order to express the necessity of studies of this type, a summary and a list of natural disasters and problems that have taken place throughout the Iranian railway network in recent years has been reviewed and, in particular, this basin has been examined and the results are presented.

In the years after the end of World War II, the transfer of human resources and the resulting developments led to the emergence of a phenomenon called "Developement", which become a slogan especially for the Third World and in particular the newly independent states. Between the 1950s and 1960s, development was often considered as an economic phenomenon. The basis of this mentality was the theory of economic growth. This theory considers the growth of a country in terms of economic development, and believes that with the increase of GNP, the conditions for the equitable distribution of development arise, and the growth process develops in the form of “Trickle-down” and spreads to deprived areas. The theory of economic growth attributed the increase of production capacity to the concentration of capital and, in particular, locating production centers in the vicinity of large cities. According to this theory, most developing countries began to concentrate on industrialization and capital investment to raise their production capacity. Having more products and raising revenues were considered as the highest factors in development. Many developing countries considered economic development to be possible only through industrialization, especially an industry whose raw materials were imported from abroad. In Iran, the development was introduced in its new meaning after the Constitutional Revolution. The entry or, in other words, the accelerated and rapid influx of capitalism into our country was a major reflection of the the statesmen’s (especially during the ascendancy of first and second Pahlavi monarchs) imitation of the capitalist system of the West in order to develop the country. The government tried to implement the ideas of modernism in all socioeconomic and political dimensions in the country, and, without paying attention to the long history and infrastructures that caused the economic and social changes of European countries, they concentrated all their attention and determination on this matter through hasty decisions and actions. In the same way, after 1921 certain points in the country were selected and all the envisaged scenarios of development and changes were implemented in these areas. This means that industries, factories, military garrisons, government departments and organizations, new social institutions, universities and higher education centers, etc. were established in these selected centers, which, of course, were connected together by roads and railway lines. The existence of such a development led to the intense concentration of all facilities and power in one or a few regions and imbalance in the regions of the country, so that the other areas to were marginalized.

This research was conducted to investigate the factors affecting landslide formation. In this regard, after identifying these factors, the fashions of occurrence of this phenomenon in some places, including the district of Shahrak and Barikan in Taleghan and the road of Haraz in areas such as: Mobarak Abad, Jajroud and Emamzadeh Ali have been addressed.

This paper examines the various aspects of feasibility of developing electronic residences in order to help decision makers and planners to have a realistic view of the subject. Feasibility studies are tools that can further clarify the conditions for the planners. Feasibility studies attempt to optimize the existing conditions by eliminating a part of the instability. In this paper, the reasons for the study of electronic residences, the concept of electronic residences (villages and cities), the dimensions of feasibility analysis of the development of electronic residences and suggestions for improving the process of feasibility examination of electronic residences. Consideration of the various dimensions of feasibility studies (economic, technical, political, social, etc.) are among the other matters mentioned in this article.

Data extraction from satellite images has significantly developed in recent decades, and various algorithms have been introduced to extract information from satellite imagery, each of which has advantages and disadvantages. In general, the methods of classification of satellite images fall into two types of supervised and unsupervised classifications. Furthermore, supervised classification methods are divided into two parametric and non-parametric methods. In this paper, the purpose is to introduce and study the algorithms of parametric supervised and unsupervised classifications of satellite images in terms of accuracy and method of extracting information. Finally, by comparing the algorithms of the existing methods, we conclude that the method of maximal similarity is more accurate than the minimum distance and parallelepiped methods, but it is still not possible to achieve the desirable precision in classification using this method. In fact, statistical methods such as maximal similarity can not be used if the goal is acquiring high precision, because the method of maximal similarity is a completely statistical method, and therefore, it can not provide the ability to accept and use external information in a non-statistical form such as geometry of imaging, geometry of features whose images are being taken, as well as effective factors such as the atmosphere in the classification process, and this is one of the weaknesses of maximal similarity classification in comparison to model-based methods. Therefore, methods such as model-based and science-based have been introduced to improve this method and eliminate its problems.