Why do mappers need control
and intelligence anyway ? Dr. Donald R. Woodley, Dr.
Tarek M. Elgarf Intergraph Corporation (IW-17A6) One Madison Industrial Park Huntsville, Alabama 35807 USA Abstract In order to deal appropriately with the critical features of the continued growth in the population and infrastructure of developing countries, there is an apparent need to strengthen the capability of natural resource agencies to collect and manage spatial information. However, it is not just the existence of land-related information which will help decision making by government, business, industry and individual residents. Rather it is the timely access to reliable data that is important. Generally it has been accepted that a geographic information system is a digital computer system which allows users to collect, manage and analyze large volumes of spatially referenced and associated attribute data. Seldom addressed during the early design stages of these systems for natural resource applications are the issues of appropriate attribution and the effects of positional control on the relative accuracy of the resultant information. It is recognized that the costs to capture the spatial data sets from remotely sensed information and existing maps and the associated intelligence for use in a resource management system can be expected to far exceed the cost of hardware and software: and often the standards of accuracy and minimum reliability of the information must be related to the local situation. However, in creating the data sets for resource management positional control, data encoding schemes, topological data structuring, attributing of information and selection of file structures must all be performed in a manner to support the users applications. This is a set of complex and time-consuming tasks, particularly for the inexperienced user. Failure to capture the correct data in positional correct form, with adequate associated attribution is likely to result in the management system being unable to support its intended users. This paper will introduce the reader to various issues related to the potential and limitations of creating and maintaining modern digital maps and attribute information. These issues include aspects of map data collection, control accuracy, intelligence and utilization. Introduction Effective resource management is based upon the premise that the same land information regularly is needed by many different agencies, organizations, and individuals for a disparity of purpose. Historically the traditional maps and surveys were valuable tools for representing these data in space. However, the hard copy maps have the disadvantages of relatively low accuracy in terms of positional error, they are dated to the time of compilation, and the intelligence conveyed to the use is limited to the contents of the printed map. Initial creation and subsequent updating of printed maps by traditional cartographic techniques is a time-consuming, tedious process requiring manual drafting, scaling and transfer of information from one map source to another. Typically these processes periodically require significant investments of time and capital to minimize obsolescence of the cartographic products. In contract with the methods employed to produce the traditional cartographic products, most state-of-the-art digital resource management systems (RMS) possess full functionality for entering, storing, updating, retrieving, and analyzing spatial information: many of these operations can be accomplished automatically. The resultant data sets are unique in providing the geographic positions of features which are related to known coordinate systems, and which describe the spatial and topological relationships among features in the digital information. The essence of RMS is the ability to link a multitude of resource related attributes, often from many different sources and maintained by different organizations, to a unique geographical location or area. However, these digital systems also have shortcomings which must be considered by potential users. The manual cartographer nearly always works with the entire map sheet, whereas in the computer environment, operators typically work with only a portion of a data base. The production map generally presents marginal information regarding accuracy, scale, and data sources: in the computer environment, the user may not have access to information on the data sources, accuracy, or even the compilation scale of the origin map data. As a result of these constraints the digital cartographer may loose perspective on fundamental issues regarding the sources and compilation of the map information. It is likely that future RMS will reside in digital computer systems which have been programmed to manage resource data and to allow many different methods of analysis. Common throughout much of the contemporary cartographic literature are the basic requirements for this kinds of systems: to have cartographic, geodetic and cadastral data bases as the common thread which links ownership parcel data and administrative/political information to all resource-related information. Structuring Intelligent Maps The key to understanding a resources management information systems is the general concept of levels or layers. Information in the system can be vowed as being sorted by type and stored in a series of separate layers. For different purposes selected layers can be retrieved from the system and combined in a multiplicity of combinations. The RMS can contain tens or hundreds of layers of data concerning the soils, slope stability, geology, forest cover types, wildlife habitat, flood hazards. Seismic hazards, property or lease information. Predominant land use and other data types deemed pertinent to the user. Each classification f data usually contains two types of information which may reside on one or two layers: descriptive text and the locational descriptors. The most important layer of any functional RMS is the geodetic control information. The function of this layer is to provide a common reference base for precise alignment of multiple themes of resource information. Land and resources can be described in many ways: but each systems requires a physical point or series of points as reference. Proper management requires an accurate description of location: a reference frame work tied to monumented geodetic control points is essential to permit subsequent combination of information from multiple layers. Another important layers is the cadastral information of ownership parcel boundaries and data relating to the ownership or lease of the property. In most Asia-Pacific countries property ownership is the primary land entity which defines the location and the rights to the use of the land. Clearly, there is a need for accurate and continuous updating of ownership boundaries with in a specific jurisdiction to which all other layers of information may be referenced through the use of a unique indexing system. This index is critical to management of the land inv3ntory within the RMS and the parole is the fundamental unit of the digital information. The third important layer is the cartographic representation of the land base. Once the geodetic control has been established, the major land features that can be easily identified are placed on the appropriate base map layers. Transportation, streams, lakes, political boundaries, and cultural information are commonly included in the cartographic layers. These “base map” features make it easier to visually locate other information in the system. Control Issues Control information is one f the most important and critical issues to be considered in developing any digital resource management system (RMS). Appreciation of the value of control information may be established if one recognizes the essentially of its utilization in:
Geodetic Mmethod Various types of geodetic observation are introduced in order to precisely determine the spatial positions of some natural or artificial ground monuments. These observations may consist of a collection of distances, angles and coordinate differences. Global positioning systems (GPS) may be considered as the most modern techniques of geodetic control data acquisition which generally consists of tracking, receiving and recording, specific satellite signals. These signals are digitally processed in combination with signal codes (Ephemeris) in order to compute three dimensional coordinates ground positions. The more conventional geodetic techniques consist of angular and distance measurements. These measurements are processed taking into consideration the curvature of the surface of the earth. The result of the process is geodetic coordinates systems. The conversion process depends upon the adopted map projection as well al ellipsoid parameters. For smaller areas of the earth, the conventional ground surveying geodetic techniques can be utilized to provide minor control as a well as data collection of ground feature details. In these local area case, the effect of earth curvature may be neglected since its influence is too small to be considered (the difference between the chord and are distance of 18.5 km is 1.0 cm). Geodetic techniques are the most accurate methods of providing control for referencing of special data. However, collection of data on feature details using this method maybe considered costly as time consuming. Photogrammetric Methods The photo grammetric method is a versatile method for collecting ground feature details as well as control data. This method is comprised of two major phases. The first phase is aero triangular which is used to compute supplemental ground control coordinates. The supplemental control is required to relate image or stereo scopic model coordinates with their correspondents in ground system. The second phase is map digitizing compilation. In this phase, analytical or analog stereoscopic plotters interfaced with computer graphic systems are used to create digital maps. The process of data collection is simply achieved by tracing features in the stereoscopic models and storing the information in digital files. Photo grammetric methods have the advantages of providing high accuracy and allowing for digital map update, checking and renewal processes. In general, the accuracy of photo grammetric methods depends upon the quality and scale of photography or imagery, amount and distribution f ground control points as well as the method of data handling. Obtainable accuracy of 1:4000 scale photography can be in the range of few centimeters on the ground. It is very important to recognize that control information is not limited only to provision of control points. Control information includes the directly accessible on-the earth-surface features details represented on the base maps such as transportation networks, cultural features, and drainage systems. The base map information is very essential for incorporation of all other thematic information including soil classification, habitat zones, predominant vegetation types, and infrastructure areas. These features details can be collected utilizing photogrammetric and ground survey methods. However, it is very important for digital RMS developers to recognize that available hardcopy maps and ortho photographs can be valuable source of base map information. As information is captured from these sources the digital base maps are compiled during the process of digital map conversion (DMC). There are two major techniques associated with DMS: automated and manual. The automated method consists of scanning the available hardcopy material to produce a raster based digital copy. This can be converted in to line work or vector format utilizing a specialized software. The manual method consists of tracing the features located on the hard copy map or Ortho photograph on a digitizing surface with a tracking device interfaced with a computer. As a result, digital files containing the traced features will be constructed. These files can then be displayed and manipulated showing the digitally converted maps.
Data on the use of information technology by countries through out the Asia/Pacific region has been examined. From these data it is reasonable to conclude that the amount of computing power used by the respective governments for resource management, and there fore their dependence on that technology will continue to grow. It is difficult to conceive of these large bureaucracies functioning without modern “intelligent” systems. Likely the public and private demand for services, and improved responsiveness from them, will continue to escalate in the future within both the developed and developing countries. Digital RMS technology offers not only the potential to make computer systems more efficient and responsive, but to change the ways that users of the technology perform their work. Over the next decade many resource management decisions made by governments of the region will be accomplished electronically. And, because the private sector will be using this technology extensively in many situations, interactions between the resource managers and the government entity will begin to occur via digital computer. The management of resource information should be a process that can assist in the effective administration of land throughout the Asia/Pacific region. It should provide accurate and complete information to the respective bureaucracies and be prepared to respond to change at all levels of government. This can only be done through coordination of independent efforts, the effective use of technology by government organizations that are implementing a RMS, and the adequate financing of systems improvements. Government agencies and others using land information systems have an opportunity to coordinate related activities and take advantage of advanced technology. TMs technology is currently used by resource scientists around the world for a wide variety of applications such as mineral extraction, timber harvesting, wild life habitat identification and management, and monitoring of coastal erosion. Digital resource information is an investment, an essential tool for decision making, and a means for better management of tangible resources. The value of “intelligent” digital resource maps shall be determined more by when the information is available to the users rather than by the costs for making it available or the content of the data. The value of intelligent maps increases with the amount of resource data involved and the depth and breadth of analysis tools provided. The technology behind all information management is advancing very rapidly, benefiting both the graphic and non-graphic elements in resource management systems. Resource management agencies need to take advantage of existing and developing data base management capabilities which shorten system development time, increase flexibility, and lower maintenance costs. What are the problems and constraints to implementing digital resource management systems through out the Asian/Pacific region ? The need for basic resource information is found at all levels of government and through out the private sector. Currently the most significant constraints inhabiting the effective utilization of resource information are the institutional barriers of the respective governments. These barriers are the result of bureaucratic evolution and their historical focus on organizational missions. The lack of accessibility to information is the most common manifestation of this problem. A government official or private individual requests information that cannot be made available because it has not been collected, the information is out dated or it will require unreasonably long or individual searches to find it, or bureaucratic policy prevents dissemination of the information. Another significant problem is the duplication of data and effort caused by unfocused responsibility: different levels of government collect the same data for different purposes. For example, the government of Malaysia might collect data and produce national or regional summaries to highlight erosion problems caused by mining operations: but the data may be aggregated in such a manner that it cannot be used at the local level where much of the resource management and enforcement activity occurs. Data conversion and other initial costs associated with the development of an integrated RMS also need to be overcome. Confidentiality is an additional issue that can limit resource information sharing when one or more items in the data are subject to legitimate restrictions on distribution. Summary : An optimum resource management system is integrated and incomprehensive. Forestry and agriculture agencies, public utilities, transportation, mining, tax assessment, and planning organizations are among the Asia/Pacific government bureaucracies typically involved in collecting and sharing resource management information. Different levels of these government bureaucracies also have the need to share information to accomplish their assigned responsibilities or to reduce application of data collection efforts. Within every country there needs to be a structure able to support basic map and other land distribute information and to serve as a frame work for referencing spatial data to the cadastral base. Current technological developments, especially in satellite surveying, provide a new opportunity to treat the necessary geodetic network in a shorter time, with greater accuracy, and at a lower cost than more traditional technologies. Uniform base maps and automate cartographic data are required both as a reference for cadastral and infrastructure information and for efficient integration of resource and land use data. The base maps must be accurate enough to display property information, and, as previously noted, must be fed to the geodetic network. Improvements in automated mapping systems, topological data constructing, and object-based systems offer users an opportunity for vast improvements in the management of resource intelligence. While there has been considerable progress in improving the quality of the vend for offerings for resource management systems, both in the quality of geodetic referencing and in data servicing, there has been less progression developing a coordinate systems to address the total requirement at the country level. To succeed in the long-term, a RMS must be protected by shifting the emphasis from the vendors’ system technology to the institutional frame work with in which the system is to function;. Those countries which contribute the basis for a coordinated system will help provide the uniform high quality resource information data base that is critical to the management of their irrespective national development and resources. The development of an integrated resource information management system is seldom an objective which can be achieved in one step. Implementing actions must be tailored to the needs, regulations, policies, and capabilities of the individual countries. |