The use of GIS National Survey Authority
by Mr. Abdallah Bin Ibrahim Al-Balushi,
Staff Officer, AutoCarto,
National Survey Authority, Oman.
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1. INTRODUCTION
1.1 The National Survey Authority is the national mapping agency of the Sultanate of Oman. It was established in 1984, replacing a small Ministry of Defence Office which had been responsible for the procurement and supply of maps and aerial photographs for both Defence and Civil purposes. Presently it has a staff of approximately 300 to meet the expanding geographic requirements of a fast developing country. The responsibilities cover all aspects of on-shore surveying and mapping for military and civilian purposes, excepting engineering and cadastre. In particular the NSA provides for
(i) Geodetic and topographical surveys.
(ii) Specifications, quality control and contractual arrangements for surveys and mapping.
(iii) Revision and production of both Conventional and Digital Maps.
(iv) Custody, security and supply of all geographic materials.
(v) Development of a National Geographic Data Base (NGDB).
1.2 I wish to draw attention to the particular issues which the NSA has experienced in developing the NGDB supporting map production and the digital data needs of NSA's customers for their GIS systems, for that may strike a common chord with many of you. I will then briefly cover NSA's use of GPS, a technology that we have been able to absorb quickly to great advantage, thereby revolutionising our Geodetic and Field Survey operations and I will then give a brief review of other planned and current major projects which may be of mutual interest.
2. CONSIDERATIONS AFFECTING CREATION OF A NATIONAL GIS
2.1 Funding
NSA is an integral part of the Ministry of Defence with a modest budget to support military requirements for geographic information. Financing the rapidly expanding civil needs is done through allocations from the concerned Ministries proportionate to their requirements, and to a lesser extent by direct payment for maps, aerial photography and services to publishers.
2.2 Assessing Needs
Considerable effort has gone into assessing the path ahead, via both commissioned studies as well as a continuous process of reappraisal. However, as yet there has been no conclusive study to gauge the transactional levels of information flow from the yet-to-be-commissioned NGDB to the client Ministries and other users. This is a major issue affecting most countries developing a national GIS strategy. Some hold the viewpoint that there must be a proven quantifiable need to justify the GIS, whilst others argue that a successful GIS will generate a big increase in information transfer to the betterment of the country. NSA holds more to the latter view. Military geographic requirements for Command and Information Systems are essential for maintaining the effectiveness of the Armed Forces, and must be addressed also.
2.3 Feasibility
2.3.1 The first step along the GIS path was the commissioning by the Supreme Committee for Town Planning of a Feasibility Study undertaken on behalf of the Sultanate by a consortium consisting of a local Agency supported by their American Associates who are acknowledged as international experts in the field of GIS data capture and implementation. This consortium became heavily involved with the Sultanate's specialised requirements from the very outset and were responsible for the preparation of the initial Milestone Reports for the Supreme Committee for Town Planning. These Reports were compiled following intensive liaison between the Consortium and all the intending participating Ministries to the introduction of GIS into the Sultanate.
2.3.2 Because the Consortium had been so heavily involved from the outset, the National Survey Authority subsequently commissioned them to develop and produce a digital mapping/GIS specification. The result of this was the production of Documents listing all the Feature Codes and Attributes for the basic mapping scales of 1:5,000, 1:20,000 and 1:100,000. It has to be said that the NSA had to subsequently input a lot of effort into editing the Documents as presented, in order to adapt them to local topographical features and environment as opposed to the different type of environment to which they appeared to have been addressed. After necessary editing and re-submission to the NSA, these Documents subsequently formed the basis for further input by the NSA's current Consulting Resident Staff who have produced a definitive set of Documents entitled Feature Attribute Coding Catalogue (FACC) which now forms the basis for all digital data capture, whether undertaken in-house or under contract. The FACC is a living document subject to continual revision and updating.
2.4 Recruiting
a. Recruiting is proving to be a very difficult area as there are several levels to consider:
(i) The Project Director/Senior Management level.
(ii) The Middle and Lower Management working interface e.g. System Managers or Programme Analysts or QC Supervisors.
(iii) The Skilled Technician level.
(iv) The new recruit/trainee operative level.
b. Although Sultanate of Oman is reasonably well-placed with regard to per capita income, it has been difficult to recruit top-quality GIS specialists at the senior management and the intermediate professional levels at the salary rates that the current market dictates. In-depth experience of mature systems is essential for establishing and running a complex National System but unfortunately accomplished Managers with the practical background and the qualifications to do so are in great demand. No National Survey can risk being indecisive in this field. The penalties in cost and effort of getting it wrong are enormous. In the case of the NSA we have felt obliged to adopt the expensive but more certain course of retaining a firm of professional consultants with a good and proven international track record. This can only be an interim solution and post consultancy management is currently being addressed.
c. The shortage of skilled technicians is scarcely less acute, but is more readily resolved. Unlike the professional management area, where breadth of experience is a prime factor, persons with basic education and computer aptitude can be reasonably quickly trained as operators for specific functions, and their skills developed on a modular basis.
2.5 Training
a. In-country programmes require a very high level of experience and skill for effective tuition. Professional training at overseas institutions is expensive and, moreover, takes staff out of the workforce and the on-the-job atmosphere wherein many good GIS ideas are generated. The NSA approach is a blend of ways; i.e. overseas training for the supervisory and managerial levels, local training of technicians by consultants and an on-going NSA programme of on-the-job training for basic operators.
b. The NSA has recently established a Training Wing which incorporates GIS training at the technician level. There are adequate numbers of graduate and non-graduate trainees currently coming forward so the shortage of skilled technicians will gradually decline. Nevertheless, the need to find top quality technologists, at all levels, will remain acute in the short to medium term.
2.6 Interaction with other Omani agencies in GIS
Whilst development of a NGDB and National GIS form part of the National Development Programme, there are conceptual differences in the way GIS is viewed by different agencies, including different database requirements and the issues of confidentiality and security. It is pleasing to note that all Government agencies in the Sultanate of Oman have taken a very positive approach to the subject. There has been full agreement to the NSA being the central repository of topographical data in the form of the National Geographic Data Base (NGDB). Other agencies will access it as a digital topographical platform on which to overlay their thematic data interactively. In the process, common data formats have been agreed based on ARC/INFO. Sultanate of Oman is in the fortunate position of having complete compatibility from the start, along with the capability to use data from many different sources.
2.7 Role of the Supreme Committee for Town Planning (SCTP)
2.7.1 The Supreme Committee for Town Planning was set up to be responsible for and to advise on all matters with regards to Development Planning within the Sultanate. Part of the SCTP's responsibilities involves coordination of all Governmental GIS activities within the Sultanate. This also involves acting as custodian for the main GIS Data Base to which all the participating Ministries will have access via the SCTP.
2.7.2 The NSA's role in the Sultanate's GIS set-up is the provision to the SCTP and updating of the National Geographic Data Base. This is populated from existing and future digital mapping projects, all of which are based on the Arc Info data structure to NGDB requirements as set out in the Feature Attribute Coding Catalogue (FACC) documents. The NSA has the sole responsibility for the provision of and maintenance of the NGDB.
2.8 Role of GIS Consultants
The NSA has entered into a two year consultancy arrangement with an internationally renowned American firm of GIS consultants. This involves full time on site representation of two GIS qualified Resident Staff backed up by a team of 16 specialists in the United States. The role of the Consultants is many faceted and includes consultancy advice, tuition and hands-on training of NSA staff in the setting up and operation of procedures for computer assistance in the cartographic process. The Resident Staff also assisted NSA staff with production of the Feature Attribute Coding Catalogue (FACC) documents referred to earlier, and an automated system of quality controlling project work submitted to NGDB specifications. They have also been involved in revising the NSA's existing digital mapping specifications which were originally to AutoCAD format to tie in with the more recently adopted Arc Info structured NGDB format, and are now assisting with the development of a computer assisted map production system.
3. ACHIEVEMENTS BY NSA IN PROVISION OF GEOGRAPHIC INFORMATION SYSTEM
The responsibilities of NSA in connection with this system are represented by quality control of digital geographic data for populating the NGDB, production of mapping at a range of scales from the National Geographic Data-Base in addition to the management and maintenance of all geographic materials and information of the Sultanate, and the ensuring of the quality of this information. To achieve its goals and discharge its responsibilities NSA has carried out the following works:
3.1 The Development of QC:
A rigorous quality control process for geographic data in a digital form before entry in to the NGDB is essential if the integrity of the data base is to be ensured. In view of the need for a comprehensive quality control process part of the quality control has been done automatically with a view to speeding up the process considerably. For this purpose AML programmes were developed
to do the automatic inspection and hence detect errors. This is much faster than the conventional method. As some items are difficult to inspect using the automatic method and require special experience it is difficult to depend entirely on the automated method for quality control.
3.2 The Development of Spec (FACC):
The spec written for this production which is known as Feature Attribute Coding Catalogue and which is available at various scales has been developed, amended and distributed to contractors and all concerned authorities. This does not mean that it is in its final form. Any reasonable developments that arise may be incorporated in the spec.
3.3 The Development & Design of NGDB:
NSA is responsible for producing, developing and maintaining geographic materials and information of the Sultanate, and within this context the design of the National Geographic Data-Base (NGDB) has been finalised with the data remaining to be entered. In this way it would be easy for any person wishing to obtain any geographic information to use the computer to obtain what is called "Metadata" which is data about the data available in the NGDB and which provide any user with details on the geographic materials and information available for the Sultanate, whether this information is in the form of digital data, Hard copy maps or even aerial photography. This facility provides the user with all details pertaining to the required material, e.g. date of issue, edition, scale and information about the quality and accuracy of the data and its source based on the DGIWG DIGEST and FGDC standards for positional accuracy, attribute accuracy, logical consistency, completeness and lineage. With the Metadata the user is free to search for data using electronic Atlas which is graphic query tool to look for the required information. Oracle Personal 7 has been introduced in the design. With the expansion of the National Geographic Data Base the NSA has drawn up a three phase, long-term plan to shift from Oracle 7 to International Oracle Server. Initially, data will be held off-line but the use of an on-line server by Phase 3 will enable the full NGDB to be held on-line.
3.4 Change of NSA System Strategy of Work:
The existing strategy of work for GIS product, is that the contractor deliver the maps in Arc/Info format as a final deliverable because this is what has been agreed between NSA and all the system user from the government. NSA conclude after detail studies that the agreed format of data will be useful only for GIS user and not for example for high quality cartographic production and for other reasons like the complexity of quality control of this product. Now and after a lengthy study conducted by the consultants in coordination with NSA staff, the NSA intends to introduce some amendments to the strategy of work using this system without affecting the data which the NSA undertook to make available to users in Format. In other words the strategy will not affect the responsibilities entrusted to NSA. The new strategy the NSA plans to implement is for the producing agency, whether in-house or under contract, to provide digital data in a format such as AutoCAD or Microstation. This will be converted to the NGDB structure and entered in to the NGDB. It is then available to customers after conversion to the appropriate structure as required.
3.5. The Advantages of the New Strategy:
With this strategy NSA achieves the following advantages:
a. Reduction of costs.
b. Provision of maps in more than one Format. Thus NSA can respond to demands very quickly.
c. Quality control process becomes easy because according to the new strategy Q.C. is done in AutoCad which is easier than GIS.
d. Remain in PC base and limit whatever available in workstation which is cheaper and easier in terms of technicality and cost.
e. As NSA produces high quality cartographic maps and in view of the limited availability of GIS systems it will be easy for NSA to use these data for production of digital maps from updated data before being converted to GIS.
f. It makes it easy for any person to look for the digital geographic information available in NSA as he may wish before making an official request.
3.6. The Current and Planned Major Digital Base Mapping Projects
This table lists the digital data sets currently available, in production and planned to be put in to work in the near future once approved.
3.6.1 Current Available Digital Data Sets:
|
Project Name |
Scales |
Format |
|
1. GTO I |
1:2000, 1:5000 &1:10,000 |
AUTOCAD |
|
2. GTO II |
1:2000, 1:5000 &1:10,000 |
AUTOCAD |
|
3. IZKI |
1:2000, 1:5000 &1:10,000 |
AUTOCAD |
|
4. SOHAR |
1:2000, 1:5000 &1:10,000 |
AUTOCAD |
|
5. 21Villages |
1:2000, 1:5000 &1:10,000 |
AUTOCAD |
|
6. Greater Muttrah & Bawsher |
1:2000, 1:5000 &1:10,000 |
AUTOCAD |
|
7. LTMP - YR1 |
1:2000, 1:5000 &1:10,000 |
AUTOCAD |
|
8. LTMP - YR1(Orthophoto) |
1:20,000 |
ARC/INFO |
|
9. 34 Villages |
1:5000 |
ARC/INFO |
|
10. Conversion of Izki,Barka &Sohar (50 Sheets) |
1:5000 |
ARC/INFO |
|
11. Digitizing of K6611 |
1:100,000 |
ARC/INFO |
Raster - 21 sheets
Vector - 2 sheets
3.6.2 Digital Data Sets in Work:
|
Project Name |
Scales |
Format |
|
1. GTO III |
1:2000, 1:5000 & 1:10,000 |
AUTOCAD |
|
2. Salalah Plain |
1:5000 |
ARC/INFO |
|
3. LTMP - YR2 Area A, B & C |
1:5000 |
ARC/INFO |
|
4. 50-04 Mapping |
1:50,000 |
Microstation/ARC/INFO |
|
5. 50-05 Mapping |
1:50,000 |
ARC/INFO |
|
6. 9 Places in Dhofar |
1:5000 |
ARC/INFO |
3.6.3 Planned Major Digital Base Mapping Projects:
|
Project Name |
Scales |
Format |
|
1. Digitizing of K6611 |
1:100,000 |
ARC/INFO |
|
2. LTMP YR3, 4 & 5 |
1:5000 |
ARC/INFO |
|
3. 50-04 Mapping |
1:50,000 |
Microstation/ARC/INFO |
|
4. Al Wusta |
1:5000 |
ARC/INFO |
4. THE GPS REVOLUTION
4.1 In discussing aspects of creating a GIS there was a considerable emphasis on the complexities and problems to be overcome. Introducing almost any advanced technology into organizations or countries that are still developing their initial technical base, gives rise to similar issues. As a counterbalance it is worth briefly remarking on the Global Positioning System (GPS), an area of interest where the NSA has quickly absorbed a new technology to considerable benefit.
4.2 GPS first came to the serious attention of the NSA about five years ago. At that time the NSA Field Survey comprised little more than a small Section equipped with a few high quality angular and distance measuring equipments. In the severe terrain and often harsh climatic conditions of the Sultanate of Oman, even modest control traverses involved a substantial exercise in planning and logistics. There were many requirements the NSA could not readily respond to, and there certainly seemed little immediate prospect of providing the Sultanate with the National Geodetic control network that was so badly needed.
4.3 Since establishing the potential, the NSA has procured eleven GPS Survey Receivers for high precision control work, as well as a large number of hand held navigation instruments. Along with some expansion of the Field Survey Department the GPS Receivers have revolutionised the NSA's capabilities. Tasks undertaken since have included the direct quality control positional checks on all of the two hundred and eighty Border monuments along the Sultanate of Oman/Saudi Arabian International Border and approximately 132 similar Border monuments along the Sultanate of Oman/Yemen International Border. The project that best illustrates the changes brought about by the advent of GPS is the observation of a primary network of 70 Geodetic First Order points spaced throughout the Sultanate. This took 6 field parties less than six weeks to complete, whereas to have carried out such a task a few years earlier using traditional methodology and conventional equipment would have taken a dedicated large project group at least 12 months. It should be noted that the NSA uses a highly sophisticated form of software named GEONAP for the post processing and adjustment of all GPS observations regardless of the type of GPS receiver used. Two senior computational staff from the NSA attended a one week's training course in Germany in the use and application of the software.
4.4 A particularly striking factor in developing the NSA's GPS resources has been the relative ease with which it has been accomplished, in contrast with the complexities of introducing a GIS. None of the professional surveyors or technicians in NSA had ever used GPS before. Yet instruction to master the main observing techniques and computations involved the services of one expert for less than two weeks. Nor has it been difficult to instruct trainees in the basic operation of the instruments. Observations for precise positioning by translocation at a number of points can be managed with only one or two surveyors supervising staff who have only minimal training, whilst kinematic procedures enable provision of rapid third order control with very small manpower and equipment resources involved. The handheld navigation instruments, which can be used by our Map Research or Cartographic staff where necessary, have also proved invaluable as an aid to revision of small and medium scale mapping where great precision is not called for.
4.5 It is appropriate in concluding this topic to express appreciation to the United States Department of Defence who have made possible the use of GPS for all, and provided such an invaluable facility for surveying and navigation. I am sure however that most of the audience here would endorse an appeal for reconsideration of the policy on Selective Availability. Given greater certainty on absolute positioning, even the small navigation type instruments perform a most valuable role in revision of medium and small scale mapping.
5. GEOIDAL MODELLING & GRAVITY DETERMINATION
5.1 One of the major shortfalls in the Sultanate of Oman's survey data is the absence of a reliable levelling network. The Sultanate contains vast areas of desert terrain to which access can be difficult, and experiences very high temperatures during the hot summer months, which make daytime spirit levelling operations virtually impossible.
5.2 With the adoption within the NSA of GPS techniques, more and more reliance is being placed upon obtaining heights for mapping purposes, especially in remote areas, from GPS observations. Delegates will be aware that the GPS output includes x and y coordinates in terms of WGS 84 spheroid and datum, and spheroidal height values. To convert the spheroidal height values to local geoidal values (i.e. to Mean Sea Level) requires a "geoidal correction" from an accurate geoidal separation model. The geoidal separation model currently in use at the NSA is OSU 91A which was developed by the Ohio State University. Unfortunately, insufficient input data existed in the Arabian region for the model to be totally reliable in the Sultanate of Oman and variations between GPS derived and spirit levelled height values from +3 to -4 metres have been detected.
5.3 As a short term solution, localised adjustments are applied to the OSU 91A model where accurate spirit levelled geoidal values are available in the vicinity of the area under survey, but this can only be regarded as a temporary solution.
5.4 For the long term, a more permanent solution is required and the NSA is in the process of creating its own localised geoidal separation model. Field work has already commenced on an extensive campaign to observe field data as input to the model. This data takes on a variety of forms including:
(i) Gravity observations for which two absolute gravity stations plus a network of 37 Fundamental Gravity Stations have already been established and observed, together with a large number of free air anomaly gravity stations to fill in the gaps in the existing extensive gravity network which has been carried out for geological and exploration purposes, and which will be used in the modelling.
(ii) Direct spirit level connections are being observed to GPS geodetic control stations, as well as GPS observations for spheroidal height which are being taken at existing reliable Bench Marks.
(iii) Astro-geodetic observations have already been taken along a large section of the western boundaries of Oman.
(iv) GPS observations will be taken at intervals along the whole extent of eastern seaboard to enable spheroid/geoid comparisons to be made with directly observed mean sea level values based on tide guage readings.
6. CONCLUSIONS
In concluding, there is no doubt that many of the related issues associated with GIS will have a familiar ring. Regional training centres may be one answer, and a non-vendor-based exchange mechanism through which countries with mature systems could disseminate their expertise, and developing countries could share their developmental experiences and problems. The greatest danger for developing countries embarking on GIS is to fall into a situation where planning and implementation become computer industry driven rather than user needs driven such that limited resources are wasted on inappropriate technology, inexpertly applied. And with regard with GPS it can be said that the relative ease with which system can be introduced and applied, and the saving in technical resources compared to previous methods of establishing survey control, demonstrates that a new and complex technology does not necessarily create new and complex problems. Indeed such new technology can reduce the dependence on expensive expertise. It must be for international conference such as this one to ensure that investment in GPS is not jeopardised by unexpected changes in policy affecting the integrity of the broadcast data.
Finally, in summary, I have covered NSA's role and development of the Sultanate of Oman's GIS and NGDB capabilities, and described our activities relating to GPS and Geoidal Modelling.
Thank you for your interest. I shall be pleased to take any questions that you may have and discuss any matters in more detail with you individually during the Conference if you wish.
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