Potential of GIS in the GULF-Region
Gottfried Konecny,
University of Hannover,
Germany.
| Abstract Of The Paper & The Profile of The Speaker | Speaker Index | Paper Title Index |
1. Sustainable Development
The United Nations Conference on the Environment and Development in Rio de Janeiro 1992 (UNCED Rio) has in its Agenda 21, Chapter 40 documented the information needs for the protection of the environment for future generation, while economic development of the globe must go on to eliminate injustices. The process of sustainable development is only possible on the basis of the availability of geographic data and the continuous monitoring of such up to date sets.
The UNCED Rio Conference has changed the general approach to development. Before there were purely economic considerations prevalent. After Rio the goal is an integration of economic, ecological and social parameters with the consequence, that sustainable development should contain a 10 % information component for the maintenance of an environmental information system.
For such a system key data sets have been identified. The first requirement for such sets is that all data can be referenced with respect to a sufficiently defined geocoded reference system. The second requirement is that all data are homogenized with respect to a well defined classification scheme of objects.
The 17 global key data sets suggested by the United Nations are:
land cover
climate
population
economic activity
topography
land status
biodiversity
human health
soils
atmospheric chemistry
trace gases
water quantity and quality
oceanography
palaeoclimatology
education
decision making
global change
Such a key data set permits to monitor on a global scale
resource consumption or depletion
pollution
population growth
poverty
soil degradation
fresh water availability
biodiversity
monitoring of disasters.
This monitoring is required because of the following predicted scenario:
At present the world has a population of 5.8 billion, which will grow to 6.25 billion in the year 2000. This population is expected to double up till 2050. Already at present 80 % of the population lives in developing countries, and it is there where the alarming population growth occurs. The consequence of this growth is the increased need for food, requiring a tripling of the present agricultural production, with an effect on the present water balance paired with the need to control drought and erosion.
Also on a regional and local scale the monitoring is required of
eroded forests
poor crop yields
wastelands
dumps
drought areas
floods
sedimentation
soil erosion (desertification)
the controlled or uncontrolled growth of urban areas.
2. Definition of a GIS
A Geographic Information System (GIS) is thus not only a computer system, capable of input, storage, manipulation, analysis, and output of geographic data, but in its widest definition a data system to manage the environment for sustainable development for the analysis of data, for planning, for decision making, and the implementation of decisions.
The name G.I.S. is in this context synonymous with E.I.S. (environmental information system) or L.I.S. (land information system) when the emphasis is placed on certain aspects of sustainable development.
The content of such a spatially oriented information system consists of three major components:
the hardware/software system supplied by the about 300 vendors worldwide, of which only very few have gained major significance;
the data system containing data of three types:
geometric data in vector form for field surveys and for vector digitized or raster scanned and vectorized map data defining points, lines, areas and objects;
image data for pixels in raster form consisting of raster scanned maps or of aerial and satellite photos, or of satellite scanners, preferably in geocoded orthoimage form using sensor orientation and digital elevation models;
non-graphic attribute data related to points (pointers for lines and areas), lines, areas and objects;
the administration, responsible for selecting the relevant data sets, for setting the necessary and cost efficient accuracy standards, for designing cost-effective updating schemes, for analyzing the data, for planning and the implementation of plans, for monitoring progress and for using the data for administrative and public purposes.
In an analogy the hardware/software system may be compared to a car, which cannot run without petrol and roads (data), and which is of no use until the driver chooses to get somewhere for a purpose.
The data component is the most costly of the three components, and unless it is maintained, it looses its value quickly. But due to fast technological developments (GIS is technology driven) hard- and software also needs frequent upgrades, and it is wise to affiliate with a vendor who can guarantee continuity of development.
3. Tasks to be solved by GIS
We must distinguish between a project GIS, which serves one project for one user only. There is no need for updating, and no need for integration by multiusers.
More relevant is an integrated GIS, which concerns systematic data collection with updating schemes and is cause for calling GIS an integration tool.
While the automation of tasks previously performed manually does not yield high cost/benefit ratios, such high ratios can only be attained by data integration.
The needs for a GIS are scale dependent. For a global coverage the data content of a 1:1 Mill to 1:200 000 map is suitable. Such maps exist for nearly the entire land mass of the earth, even though the accuracy of the data varies greatly, and the existing maps are based on different geodetic reference systems (earth ellipsoid and its orientation, height reference systems), on different projections (UTM, transverse Mercator, Lambert, stereographic).
Fortunately GPS surveys paired with new geoid models permit to standardize different map systems, as has been done with the availability of the Digital Chart of the World DCW, comparable to a 1:1 M scale data content. At scales 1:250 000 to 1:200 000 the MegrinProject of Europe (by CERCO) and the Africover Project of Africa (by FAO) are good examples for digital data derived by map digitization and new geo-referencing. In 1999 a new corrected version of the DCW on a 1:250 000 scale will become available worldwide, it will also include homogenization of the object classes.
The regional needs are met by maps 1:100 000, 1:50 000 and 1:25 000. Maps 1:50 000 are available for 2/3 of the land areas of the globe in analog form. However on the average these are over 40 years old. Maps 1:25 000 cover only 1/3 of the land area of the earth, and they are more than 20 years old on the average. The problems with these maps is, that they must not only be geodetically standardized to a new datum (e.g. IREF on the WGS 84 Ellipsoid), and harmonized to homogeneous object classes, but that they also must be updated. The combined use of satellite and aerial images with existing or nearly digitized map data will lead to the expected result.
The local requirements for photogrammetric mapping integrated with ground surveys arise in urban areas at scales 1:10 000 or 1:5000 for planning and at 1:2000 to 1:500 for engineering uses.
Local GIS costs per km2 are the highest (500 to 10 000 $), regional GIS costs range between 10 and 500 $/km2, and the global GIS costs are at less than 10 $/km2.
In the GIS evolution a tendency has been noted, a base map, in whatever form is the backbone of a GIS, and it must be established first. The base map as a rule should be a topographic map, which shows the visible features of the earth's surface including its elevation distribution in form of a digital elevation model (where required).
Related to this base map thematic graphic content may be added. Both base map and thematic content, when brought together in a data base for joint display and analysis form the graphic data of the GIS, which is augmented by the non-graphic data base content of the GIS. This combined data system can be used for sustainable development.
In several European Countries the Survey and Mapping administrations have undertaken the task to supply base map data in various forms to the GIS user, who is expected to add his thematic graphic and non-graphic content to the base map data.
Prices for such data vary greatly. In the German State of Lower Saxony vector data for the scale equivalent of 1:1000 cost 4,200 $/km2 in urban centers, 2,800 $/km2 in the periphery of cities, 1,400 $/km2 in villages, 470 $/km2 in agricultural areas and 235 $/km2
for forested areas (ALK). Vector data equivalent to the 1:10 000 scale (ATKIS) cost 50 $ to 20 $/km2.
In Switzerland vectorized maps 1:200 000 cost 23,000 $ per map sheet, while raster scanned maps 1:200 000 cost only 1,800 $ per sheet. At scales 1:50 000 or 1:25 000 raster scanned maps only cost 500 $ per sheet. DEM data cost about 17 $/km2 at the 1:25 000 level (50 m raster).
If one compares survey costs of individual projects one can easily see that purchase of digital base map data, regardless of the variability of pricing leads to cost advantages for GIS.
GIS needs in the Gulf area are mainly within the urban environment.
The required urban data sets are:
a topographic base map to be compiled by photogrammetric mapping of visible features; an orthophoto can serve as a topographic base map substitute which is cheaper to establish, but less accurate for interpretation and geometry. A digital orthophoto may, however, be a very suitable updating methodology, when used with a previous digital topographic base map. Updates are required at periodic intervals from between 1 to 5 years. Transaction updates have usually never worked.
a property ownership (cadastral) base map. Its accuracy depends on the cadastral survey procedures and the cadastral record system in use. Property lines are generally not visible, unless visible monuments, or accurately built fences, walls or buildings have been placed and verified by survey records. A property ownership update is required on a transaction basis with daily to weekly updates. Cadastral attribute data are usually confidential in nature.
a utility services base map. In practice each utility organization maintains a utility base map only in form of a network sketch 1:2000 with survey references to visible objects (walls, buildings). Relative location of different utilities, which may save considerable expenditures in urban reconstruction is, however, rarely available. Once an integrated geometric utility data base is available for all utilities on the basis of photogrammetric mapping of identified or signalized manhole locations, it may easily be updated by transactions by each utility authority in geometry and in attribute content.
land value is an important (confidential) attribute to counter land speculation;
planning zones may easily be combined with the property ownership base map;
administrative unites are easiest combined with the cadastral base map. It is recommended to include road parcels into the cadastre. Care must be taken to properly define administrative units by those administering the cadastre, whether the administrative boundaries coincide with property boundaries, or whether they relate to road center lines.
Population Data can be referred to parcels, but are best related to buildings, as a subset of the topographic (or cadastral) data base. To building data civil ID numbers, workplaces, car registrations or health data may be added.
Building Data may be monitored on the basis of building permits, provided that periodic monitoring via topographic updates gives a check that buildings are not erected or not completed contrary to the law governing the permit.
Vegetation Data monitoring the health of vegetation may be added.
Transportation Data giving data on pavement type and age, road signs, accidents, car navigation data, police, defense, ambulance, fire police, parking, dispatch, catering and tourism may be added.
Environmental Data on ground water, soil, emissions, pollution, dumps, noise level are important assets.
The data sets may be augmented by various other data for commercial uses (data on stores etc.
4. Alternatives for the Collection of Topographic Data
The classical way to obtain topographic data is by photogrammetric line mapping. Since the 1950's mapping organizations or their photogrammetric contractors have compiled line maps by stereo compilation from aerial photos. Since the 1970's and 80's the output was in digital vector form. The horizontal accuracy of such graphical line maps is to about 0.2 mm to 0.5 mm at publishing scale, while the photogrammetric digital restitution accuracy is a function of the measurement accuracy in the aerial photographic diapositive given by
(x,y ) = (h/f ). (x'y')
with (x,y) as the planimetric accuracy on the ground, (x'y') the measurement accuracy of a point in the diapositive (now about ( 10 micrometers), and (h/f) the image scale factor, depending on the flying height h above ground and f the focal length of the aerial camera (for normal angle = 30 cm, for wide angle = 15 cm).
The photogrammetric height accuracy (z is a function of the stereoscopic measurement accuracy (px in the overlapping stereo images, and the image scale factor as well as the height/base ratio (h/b) for the overlapping photos
(z = ( (h/f) . (h/b) . (px' ;
(px' is about 7 micrometers. For wide angle images overlapping by 60 % (h/b) is usually 1.6 and for normal angle images 3.3.
Beside the required accuracy the object detectability plays a role, which is a function of the photographic resolution in line pairs per mm. Standard aerial diapositives usually yield a resolution of about 30 lp/mm in colour with image motion compensation cameras using high definition black and white film. The resolution may be increased to about 45 lp/mm.
With these parameters in mind aerial photography may be planned for any accuracy and detectability requirement.
Aerial photos of urban areas, permitting to identify manholes, fences and walls to better than decimeter level require an image scale of about 1:4000.
In up-to-date technology analytical plotters or digital stereo workstations digital map representations at a scale of 1:5000 may be compiled for these images. The choice between analytical plotter or stereo workstation depends on its current availability. If no restitution equipment exists, a stereo workstation is preferable due to its added automation capability.
Data acquisition in this manner is a relatively expensive proposition in the range of up to 10 000 $ per square km or more. However, such a digital vector coverage to ( 10 m accuracy is a most useful data base, which may be updated in image super imposition by digital orthophotos in a more rational manner.
Digital orthophotos are products of scanning the original aerial film. A scan pixel size of 7 µm is possible but due to general limitations of resolution, and due to presently possible processing times not recommended. A pixel size of 15 µm will suffice in practice.
With image processing applied the resolution or object detectability in general corresponds to the size of 2 pixels times the image scale factor.
Digital orthophotos can be produced at costs of about $ 1000. If they are made for a comparable image scale 1:4000 with 15 µm pixels this corresponds to a pixel size of 6 cm on the ground and a detectability of 12 cm for objects of sufficient contrast. If an orthophoto covers 0.5 square km then the square km price is $ 2000 or 5 times cheaper than digital line mapping.
In the line mapping as well as in the orthophoto production costs all required auxiliary efforts, such as control extension by aerial triangulation and its bundle block adjustment are included. Aerial triangulation also provides the opportunity to include digital elevation model measurements on the basis of which a grid type DEM, a TIN or a contour plot may be interpolated.
The costs of mapping or orthophoto mapping may, of course, be considerably reduced by reducing the image scale. The 1:4000 image scale is recommended for a 1:500 scale type engineering GIS including topography, walls, fences and utility manholes.
A planning GIS at a scale type 1:5000 may be obtained from an image scale 1:29 000 (the somewhat uneven image scale is the result of the attempt to compile each map sheet (or 2 map sheets) from two stereo models, and 1 (or 2) orthophotos from one image. This, even though normal angle photography is generally used for cities, which has half the height displacements and half the hidden areas from wide angle photography, will permit to avoid discontinuities within one orthophoto map sheet or one orthophoto file.
The use of such a scale will bring the square km price for digital line mapping to about 500 $ per square km, and that of digital orthophotos to about 100 $ per square km. However, objects smaller than 80 cm to 90 cm cannot be detected in those images.
A further extension of this is the use of satellite imagery. U.S. commercial systems of 1998 and later (EarthWatch, Orbimage, Space Imaging) promise eventually to reach 1 m pixels with a detectability of 2 m objects, suitable for an equivalent 1:10 000 mapping scale. Square km prices of 40 to 60 $ have been talked about for a value added orthophoto product.
At present an even cheaper satellite product is obtainable at about 30 $ per square km. This product stems from digitization of Russian space satellite photographs taken with the KVR 1000 panoramic camera. Digitization of this high resolution imagery is currently made to 2 m ground pixels with 1 m ground pixels promised by the end of the year.
Other obtainable high resolution satellite images for rectification are the Indian IRS 1C images with 5.7 m ground pixels, and the stereo images of the 3 line German inflight stereo sensor MOMS 02, which now is in operation on the Russian MIR Space Station with a 5 m vertical channel (for the detection of objects larger than 10 m) and 2 fore and aft stereo channels with 15 m ground pixels. These images are suitable for 1:25 000 type digital mapping and orthophoto generation.
Digital orthophotos provide very rapid and economic means for updating vector data bases by on-screen digitizing when the differentially rectified images are superimposed with the available, but not up-to-date vector data base.
5. Alternatives for the Collection of Cadastral Data
The existence of a cadastre depends heavily on legal practices for ownership and utilization of land.
In its simplest form land may be transferred by private conveyancing in which the scale or the transfer of land is a private contract with no protection as to whether the land really exists, where it is, or whether the past owner really has ownership rights. The buyer may buy "title insurance" to protect himself from this legal uncertainty, as is the case in the USA.
On the other hand the State may offer some sort of protection by instituting a deed register. It is a non-compulsory, voluntary registration of land in a public register for a variety of goods (goldwatch, land parcel) which is usually described in a rather non-professional manner, as for example by meters and bounds in parts of the USA.
A more advanced method of land registration is the title registration, as it has been introduced by Torrens in Australia and as it is being practiced in Canada and in parts of the U.K. The advantage of the system is that it is a compulsory measure for the registration (proof of ownership and rights to land), resulting in a title document. The system, because it is compulsory, may serve as a register for taxation and statistics. On the other hand a so-called "tax cadastre", as it is frequently established in the USA merely serves to collect taxes from all existing land. It has only indirectly to do with rights to land.
An even higher protection to the owner is the property cadastre, as it has been established following Napoleon I in most of continental Europe. In the property cadastre the State has the responsibility of record keeping and it guarantees ownership and the rights to land. It is liable for compensation in case of conflicts.
Depending on local situations in each country modifications of the types described exist.
Obviously only the land title registration and the property cadastre offer GIS capabilities. They permit real time updating based on transactions.
Accuracy considerations, however, depend on the purpose for which the cadastral system is maintained. In Central Europe, for example, the function of the cadastre has evolved with time. First, its function was to serve as a tax cadastre, in which parcels did not need to be more accurately described than to the nearest meter. But it was important to record each parcel with its area and use to assess the tax with a given tax rate.
With land becoming a scarce commodity the emphasis was placed on an ownership protection cadastre, which secures the accurate location of the property to the owner with a centimeter accuracy requirement. Most administrations now realize that the accuracy requirements for an ownership protection cadastre are the owner's concern, and not of public interest.
A reasonable accuracy requirement is that of a multipurpose cadastre with ( 10 cm accuracy which secures the public interest about property for tax collection and planning. Because of the planning requirements a multipurpose cadastre does not only require the definition of boundaries, but it must also include some topographic features, such as buildings and walls.
A land related GIS (also called Land Information System LIS) basically contains the geometric (vector) data and the attribute data in digital form.
The cadastre in its analog and in its digital (LIS) form basically contains two parts:
The "cadastral map" (geometry) and the "cadastral book" (attributes). The geometry describes the boundaries and the geometric attribute link in various alternatives, and the attributes contain alphanumeric data on the owner, his I.D. or birth date, the encumbrances and the mortgages of the parcel.
The description of the boundaries can be made in a non-professional or a professional manner. If a land parcel has been established or surveyed by a non-professional surveyor the geometry description (as is the practice in the USA) is by meters and bounds without a proper reference. For example a compass survey with tape measurements was started from a marked tree stump, and the boundaries were closed at the starting point without external check.
Professional surveys, on the other hand, require the existence of a monumented control network as a reference, to which all surveys may be tied. This can be done independently of the survey method used, e.g. by metes and bounds, by orthogonal surveys, which have been traditional in Central Europe, because no theodolites were required for surveys of detail. Nowadays polar surveys by electronic tacheometers or total stations are the rule.
The modern way to record the location of boundary points is by coordinates in a given reference system. Such coordinates may be obtained by different means:
- by calculation of survey records, which have been tied to control, whether they have
been done by metes and bounds, or by orthogonal and polar methods.
- by signaliyation of boundary locations or monuments, and by photogrammetric
restitution
- by direct measurement with differential GPS.
The survey measurements and their possible derivation into coordinates, or their direct measurement leads to a numerical cadastre with a precision of +/- 0.01 to +/- 0.20 m on the ground.
If these boundary measurements have previously served to compile a cadastral map, or if the boundaries are described by a geocoded orthophoto, then this leads to a graphical cadastre , which usually has a precision of +/- 0.25 to +/- 1 m on the ground. Such a graphical cadastre is usually easily digitized into vector form by a manual digitizer or a raster scanner with subsequent raster-vector conversion.
In many countries the geometric cadastral records leave much to be desired. There are various alternatives to arrive at a digital geometric data base with different accuracies, costs and time requirements.
The most accurate, and perhaps the most profound methodology is to compile the digital geometric data base from old survey records contained in field books and in annotated plans. If coordinate controlled, this can be done to +/- 0.01 to +/- 0.05 m. However, this is a time consuming and expensive proposition.
It is easier to digitize a cadastral map to +/- 0.25 m to +/- 1 m accuracy.
This digital output may be slightly improved to the +/- 0.2m level, if the digital record is fitted to buildings, walls or fences known from topography. Topographic surveys of such objects may of course be made in conjunction with an attempt to restore a monumented control network by ground surveys. As a rule, however, photogrammetrically mapped topographic data will be more effective to use for this purpose.
In some countries, such as in the U.K. hedges planted along boundaries define the socalled ''unsharp boundaries'', which eliminate the need for subsequent precise boundary definition. In Germany each boundary must be monumented by stones or durable plastic markers. Such monuments may be white-washed, and they are measurable in aerial photographs, as has been done in numerous rural reallotment surveys in the last 40 years. If such a surveyed monument is later lost, retracement of the boundary is possible by field surveys from survey records.
In the developing countries an effective and inexpensive means to create a cadastre is to produce large scale orthophotos and have the neighbours agree on the identified and pricked boundary locations in the images by their signature in the socalled ''photoadjudication process''.
The alternatives for the collection of cadastral data are therefore:
- cadastral map digitizing, when the result is later referenced and fitted to topographic
surveys with common topograpphy- cadastre points
- the building up of cadastral data base from survey records
- the new survey of boundaries by differential GPS, which inareas of signal loss needs
to be supplemented by total station surveys.
- the method of photo-adjudication
All these methods lead to a homogeneous geometric record.
Such a homogeneous record can, however, not be achieved, if an inaccurate, non referenced cadastral map at medium scale is used to vaguely describe and to identify the existence of a land parcel.
This ''sketch'' containing the parcel ID´s and the relative appearance and location of parcels can be combined with the results of document scanning, by which the scanned documents (ownership certificates, building permits, utility connections) may be quickly retrieved for each parcel. The Water Board of Sydney in Australia has been able to create a minimum cost- GIS by this method in only 3 years. It was based on parcel documents related to a coarse map 1: 5000, which did not meet modern accuracy criteria with respect to control and topographic content. While this approach leads to a quick solution, it, however, leads to the disadvantage that information ambiguities between parcels need to be resolved in situ on a case by case basis.
Germany and Kuwait have started with the approach to reconstruct parcel geometry from georeferenced original survey data. However, difficulties have been encountered, where many changes of the original surveys have occurred, which have been recorded in a whole sequence of field books, either by the fact, that some of the surveys were not reliable and did not include check measurements, or that simply the effort of having to consider too many field notes was too time consuming and costly. For those areas the digitization of cadastral maps is a more efficient, even though less accurate alternative, unless even more costly resurveys take place on the ground. Such resurveys should as a rule only be carried out if new survey activity becomes necessary due to new development in the area.
In Dubai an ideal combination of methods has been chosen: New areas of development are planned by digital coordinates on the work stations, after a wide perimeter survey has been carried out. The coordinates obtained in planning are then staked out on the ground. At the same time they serve as a GIS record. In developed areas cadastral digitizatin is used as a starting information, while blocks under urban redevelopment are improved in accuracy, when new surrvey data become available. The block perimeter surveys are either made by the control survey staff, when the local control network is improved, or taken from topographic large scale surveys of common points. This economizes the effort for these areas, where accuracy improvement is needed. This results in a gradual geometric improvement of the data base during a long time period. At the same time a document scanning and retrieval system is in preparation to add in the recovery of field survey information contained in previous certificates (site plans, affection plans).
6. Alternatives for the Collection of Utility Data
Utility authorities have traditionally cared little about utulities not under their jurisdiction. When they automated their maps and plans, their aim was to produce digital drawings by CAD/CAM - systems. These permitted to produce schematic drawings with graphic annotations for numbers, text and symbology.
GIS has brought in the possibility:
- to replace annotations, text and symbols by attributes attached to manholes and line
segments
- to link the line segments together (connectivity) to analyze flow and capacity
This has led into the development of facilities management and SCADA for each utility type, generating an internal business management system for each utility administration.
The Municipality´s concern, and indirectly another concern of the utility administrations, is the relative location of different utilities. This situation may also well be represented by a GIS. When attributes of depth and elevations are added to the planimetric data, a 3D representation and a 2D representation in profiles may be generated.
Again it depends on the interests of the Municipality, ist utility coordinating committee or the utility authority itself, which GIS representation will be chosen.
In the simplest case particular utility lines are placed into reservations, the dimensions of which ( e.g. 1 m from the property line, or 3 m from the road center line ) are fixed by the standard road width. In some countries the lines are referenced to distance markers placed onto walls and buildings. The utility map may in such cases be reduced to a simple sketch ( 1: 2000 ), rather than a more accurate map ( 1: 500 ).
Most utility types are traceable on the ground by their manholes. This permits to make the manholes visible on aerial photos by signalization or by choosing such a large image scale, that they may be identified and measured in the photos. Underground telephone, water, sewerage, and gas lines can be retraced in that manner for a GIS showing all utilities. The only utilities not retraceable in this way are underground electricity cables of various voltages. If these are not identified by wall markers, they may be easily related to the adjacent walls by electomagnetic cable detectors.
Kuwait established such a systemin the former KUDAMS Project. Dubai has completed a pilot project establishing a methodology to implement such a system, but before it´s introduction a cost sharing agreement between the Municipality and the utility agencies needs to be concluded. One should consider, that the replanning of a single rod intersection, for which usually digging must take place to clarify the relative utility locations, may cost as much as the establishment of the entire intgrated urban utiity management system component.
The Water Board System of Sydney has shown, that document retrieval for parcels defined on an inaccurate map, may not only be applied to property records of a parcel, but also to parcel related utilities, especially for surveyed house connections, described for parcels in utility site plans.
7. Alternatives for the Collection of Building Heights
In urban areas building heights, until recently, have only played a minor role. The number of stories was easily included as an attribute, when building attribute surveys were made, or when these were collected in transactions and listed on building completion certificates after construction.
With the advent of mobile telephones building heights become of importance, because large and tall buildings prevent the operation of mobile telephones in their shadow areas. For that reason the location of relay antennas need to be optimized for the network, making it necessary to know the building topography in height better than 1 meter.
There are several alternatives for the collection of building heights:
- manual photogrammetric height measurements on stereoplotters and
stereoworkstations
- low labour cost countries may use barometer surveys for this purpose
- an upcoming digital technology is via digital image correlation with image
matching programs. Such building height determinations are quite fast and
cost effective, with the planimetric building boundaries originating from the
GIS, and the height measurement of building tops and the ground elevations
coming from image matching
- a new methodology, the one of laser scanning, which is more costly, but can
determine building and ground heights from up to 1000 m altitude to +/- 15 cm.
8. Alternatives for Attribute Data Collection
The collection of attributes is very specific to the purposes for which a GIS is established.
In general attributes may either be collected by tranaction reports in near real time. The weakness of this method is the lack of checks.
The other alternative is a periodic collection program. One of the examples for such a program is a census. For the purpose of agglomeration of data it is most important to precisely identify and to keep the boundaries of the agglomeration units.
9. Gulf Area Uses
To make a summary of the present GIS efforts in the Gulf area within the context of this paper is very difficult. The summary can neither be exhaustive, nor complete. A few general remarks may suffice. GIS activities have been taken up in all Gulf States:
In Bahrain the emphasis is to bring the efforts of the Central Statistics Organization, the Ministry of Housing, and of Batelco under one standard.
In Kuwait Kuwait Municipality started out with the design of an integrated urban information system for mapping topography and the utilities, and the cadastre in 1983.The effort is now extended for planning. The utility ministries are now interested in facilities management, and the Ministry of Defence has automated the provision of small scale map data, which is needed in projects by KISR.
In Oman GIS uses can be found with the Ministry of Water Resources, the National Survey Authority, and with Petroleum Development.
Qatar is a leading example in the world for an integrated GIS.
In Saudi Arabia various activities take place, at Aramco and Telecom for Facilities Management; in the Military for mapping; at some Universities for projects; and in most Municipalities for an urban GIS.
In the United Arab Emirates efforts go on at all major municipalities (Abu Dhabi, Al Ain,Dubai, Sharjah) in oil industry (Adnoc), in the UAE military, and at the utility agencies (DEWA, Etisalat).
Regarding the effectivity of GIS development 3 aspects can be considered:
- the institutional ones
- the financial ones, and
- the technical ones.
In general, the technical problems are not a major obstacle in the area, neither have been, nor are now the financial aspects, But the effectivity very much reflects institutional conditions.
Technology now makes it possible to gradually move away from central administrations to networking. This can in the larger countries of the area only be done by creating interfaces in a style of an Open GIS.
There is much discussion on how a sustainable GIS can best be instituted. It is fastest established by a top- down approach. But for general use a bottom- up approach, showing the individual concerns of all involved is desirable for sustainability.
The compromise between the two approaches is the setup of an effective committee structure: a steering committee at the highest level, an application committee at the technical working level, and the creation of GIS cells in each participating agency.
The keys for a successful and growing GIS are
- a concensus of supporters
- the ability to customize vendor software to own needs
- maintenance programs for the update of the data base
- the keeping of quality standards
- education and training of decision makers, professionals and technicians
- the sharing of data to make possible their cost effective wide use
If these aspects are observed, there is no reason, why the Gulf Region cannot be one of the best examples, how sustainable development can be attained in the world.
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