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The geological map database of Great Britain: Version One complete.

So what's next?

Ian Jackson British Geological Survey

Keyworth, Nottingham, UK NG12 5GG Email: ij@bgs.ac.uk Tel: +44 115 9363214 Fax: +44 115 9363269 Web: http://www.bgs.ac.uk ABSTRACT In 2001 the British Geological Survey (BGS) will complete Version One of the 1:50,000 scale digital geological map database of Great Britain. So that’s it…….. the job's done…. time for that long vacation …… well not quite. While 1:50,000 scale cover of even a small country like Britain is a major achievement, expected to underpin many other BGS developments and products, the job is far from complete. The programme adopted a pragmatic approach to ensure availability of national digital geological map cover at a meaningful scale, in a less-than-geological timescale. This means some challenges remain to be overcome. The issues and questions a programme like this raises (and the future challenges that lie ahead), are likely to be recognised by other geological survey organisations as they attempt to fulfil their missions to continue to provide relevant geological information and knowledge into the 21st Century. Questions like: Are we building a spatial database or a digital map production system? How will we obtain the resources to manage, update, extend and improve this first version of the map database (and gain recognition for the priority of these tasks within our own organisations)? How

do we achieve consistency within the map and database and underpinning dictionaries and at the same time incorporate the latest survey data and interpretations? How do we integrate with the map database all the other geoscience data a geological survey holds? Now that the technology is available, shouldn't we move on and go for seamless

digital workflows from field to user? And when do we start to work fully in the 3rd and 4th dimensions that we have always claimed distinguishes our science from

topographic mapping? How can we supply harmonious information on pan-

national problems across frontiers, when there are no European or international standards (and often no de facto national standards either)? Finally and perhaps most importantly, do we really know what

products and services our user communities need and want from this

database and how close are we to delivering it? For it is certain that the geological map, digital or not, is a means to an end, not an end in itself. This paper will describe

how the BGS tackled the construction of Version One of the digital geological map database of Britain, summarising the issues raised by the pragmatic approach. It will also outline some of the challenges that the BGS believes to lie ahead and in doing so hopefully contribute to clarifying and resolving shared problems.

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1 INTRODUCTION Since its foundation in 1835 the BGS has been producing geological maps of Great Britain at a variety of scales. In 2001 (one hundred and sixty six years later) all existing 1:50,000 scale geological maps will be available in digital form - Version One of the 1:50,000 scale digital geological map database of Great Britain - DigMapGB50 V1 - will be complete (Figures 1A and 1B and http://www.bgs.ac.uk/Digmap/home.html). This is a major achievement, even given the relatively small size of the country. The programme has had to face a number of major scientific, technical, resource and cultural difficulties (of which the first two were arguably the easiest to overcome!). DigMap50 V1 is very much regarded as a pragmatic early step and the BGS strategy is to progressively improve the quality, resolution and sophistication of the database. Last, but not least, the BGS believes the exploitation of the database for the benefit of the end-users (of which geological profession is but one!), is the key objective. This paper describes a venture which has its origins more than 15 years ago. The work crosses professional disciplines and can be scientifically, technically and culturally complex. At times the programme has been the cause of much contention. Any attempt to summarise such work will, inevitably, be subjective and will reflect the perspective (and biases) of the author; this paper is no exception. 2. A LITTLE PRE-HISTORY The primary field mapping scale in the BGS is 1:10,000 (previously six inches to one mile) but the 1:50,000 scale (previously one inch to one mile) is the resolution at which maps have always been printed and published. Until the mid 1980s 1:50,000 scale geological maps were produced in the BGS by conventional analogue methods (at that time "scribe and peel coat"). Digital map production had been attempted in the 1970s but, amongst other things, the available hardware and software proved insufficiently mature (Bickmore and Kelk, 1972; Rhind, 1973; Loudon and others,

1980). Throughout the early 1980s, Computer-Aided Design (CAD) software and Relational Database Management Systems (RDBMS) were used in diverse projects across the BGS. 2.1 Time to stop experimenting From 1985 onwards progressively more extensive operational trials of digital cartographic techniques began to take place in the BGS "Drawing Office" (using MicroVax computers and Intergraph's IGDS software). In 1989 a robust digital system for the production of 1:50,000 maps was launched on Clipper Workstations, running Intergraph MGE/MGA software linked to an Oracle RDBMS. While early GIS software was utilised within this system, the database element was largely cartographic, being designed primarily to hold, for each polygon, the cyan, magenta and yellow colour codes necessary for colour printing. Nonetheless the system increased the efficiency of the BGS map production enormously and furthermore, provided invaluable experience in digital workflows, ie capturing, encoding and cleaning attributed spatial data. 2.2 It's not red, it's granite In 1989, at around the same time as the Drawing Office were launching their operational Digital Map Production System (later to become known as DMPS89), the Directorate of the BGS took an ambitious decision to develop a fully geologically (as opposed to cartographically) attributed map production system for the highest resolution maps the BGS produces, the 1:10,000 scale map series. While not fully understood (or accepted) by all at the time, the objective of this research and development project (the Digital Map Production Implementation - or DMPI - Project) was to create a spatial geological database, from which the 10,000 scale map was merely one possible output (Nickless and Jackson, 1993). The data structure (modelling) and dictionary specification elements of the DMPI project were therefore fundamental. The 1:10,000 (DMPS92) system attaches a comprehensive set of geological attributes to the lines, points and polygons; map colours, symbols and ornaments were a

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secondary criterion, to be selected at time of output. The DMPS92 system proved an effective method to capture data at this scale and extent of detail and over the next 4 years many 1:10,000 scale maps were processed and added to the database. But the BGS did not have the resources necessary to route all maps in its programme through the system and achieving national cover, or even cover of the major urban areas, was not going to be possible within a reasonable timeframe. Furthermore, the primary deliverable continued to be seen by the majority in the BGS as the 1:50,000 scale printed map, not a high resolution digital spatial database. 3. BEST OF BOTH WORLDS? In 1997, following much internal debate about the pros and cons of the respective systems, the 1:10,000 scale system (DMPS92) and the latest version of the 1:50,000 scale map production system (DMPS89) were merged. The intention of the merged system (DMPS97) was to combine the operational virtues of the cartographic methodology, DMPS89, with the more sophisticated scientific data structures of DMPS92. Not for the first time the benefits of having spent considerable effort establishing a comprehensive logical model of the BGS geological map data as an early task of the DMPI project, became apparent. The model provided a competent basis for deriving the DMPS97 data structure, it gave confidence in the future scientific integrity and flexibility of this particular physical implementation and also ensured backward compatibility. This "hybrid" did not completely satisfy some GIS/database specialists and geologists in the BGS, in terms of its "purity" or level of attribution. But senior management considered it to be a practical and fit-for-purpose foundation. It would capture the key components of the map data, ensure scientific integrity and at the same time continue to ensure efficient "conventional" map production. It was felt to be a viable platform from which the BGS could contemplate the construction of a national geological map database, in geologically attributed vector format, at a high resolution. More importantly, it would be the basis for a whole range of value-added products.

4. WHAT WE DID The DigMapGB project emerged in 1997 with the objective of providing nationwide coverage at a variety of resolutions (1:10,000, 1:50,000, 1:250,000, 1:625.500). An overview of the DigMapGB data components is given in Table 1. It was acknowledged that, with unlimited resources, the ideal would be to construct a spatial database at 1:10,000 scale, the highest resolution geological map data that the BGS holds for most of the whole country, but this was not feasible. On the other hand, long before 1997, there was an awareness that there was a growing demand for digital map data of the country in GIS format that needed to be met quickly. As a result complete national cover for the 1:250, 000 scale series had already been completed in 1994 and upgraded in 1996. It was completely revised again in 1998, with the conversion to lithostratigraphical and lithological coding under DMPS97 standards. However, while such smaller scale digital datasets were (and are) useful for some purposes, they were not at the high resolution that the majority of customers for BGS map data (analogue or digital) required and attention turned to the 1:50,000 scale series. In 1998 a decision was taken by the BGS Directorate to accelerate capture at this scale so that maximum national cover would be available by 2001. The DigMapGB50 project was initiated. 4.1 DigMapGB50 project organisation Following the 1998 decision a high profile project was set up and funds allocated. A cross-divisional project team was put together under a single management line. The team comprised cartographers and geologists, data managers and information systems specialists, with dedicated, full time, project staff being supplemented by many other BGS geologists and cartographers being "bought in" to provide expertise and support as required. The major role of the geologists and geological data managers was to build up the underpinning geoscience dictionaries, to provide the attributes (ie a comprehensive set of geological codes for each map) and to check the product. The cartographers undertook the in-house map capture to common standards and ensured the linkage of the spatial data to the geological

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attributes. However, a key element of the project was the outsourcing of some of the legacy paper map conversion to digital form (see 4.2). Another fundamental decision was the appointment of an experienced mapping geologist from within the field survey groups, as a project leader, to supervise and coordinate all the geological input. Sections 4.2 and 4.3 below draw heavily on an internal BGS Technical Report (Becken, 2000) 4.2 Workflow It has already been stated, but it is important to underline the fact that the decision was to complete DigMap50 V1 by a specified deadline and within an allocated budget (but see section 5.2.1). One critical consequence of this decision was that we would be largely using maps that already existed, either on paper or in an earlier digital format, with all their acknowledged geological imperfections. The DigMap50 V1 workflow reflected, to a large degree, the source data and had essentially three components (see Figure 2): • New maps captured within the BGS • Existing (legacy) paper map capture • Conversion of legacy digital map data 4.2.1 New map capture New maps being produced by current surveying, i.e. output from the GB national geological mapping programme, are captured within the BGS under the DMPS97 protocols. The workflow and responsibilities of the geologists and cartographers are illustrated in Figure 3. 4.2.2 Legacy paper map data capture This component of the project was being undertaken within the BGS since 1997 but in 2000 it was also outsourced to an external agency. Outsourcing was undertaken after competitive tender against a stringent technical specification and a series of trials. The outsourced workflow is shown in Figure 4 and is for map face data only not marginalia.

4.2.3 Conversion of legacy digital map data The task here is to convert data from the earlier DMPS89 format to the DigMapGB standard, DMPS97. Again the workflow shown in Figure 5 is for map face data only. 4.3 Technical stuff 4.3.1 Software The project uses Bentley MicroStation® and Bentley GeoGraphics® software, running under Windows NT, as the GIS for constructing the spatial databases. MicroStation® provides the graphic interface to the GIS, and allows up to 63 levels of data to be held within a "Design" file. These levels are used to categorise broad types of cartographic elements, primarily to aid the effective use of data types for processing and plotting. Customised interfaces provide tools to automate some procedures, and to present the interface to the user in cartographic and geological terms (for example customised line styles). GeoGraphics® provides the link to the geological attributes; tools for checking the geometric integrity of the data e.g. line-cleaning; and tools for generating polygons. Customised tools also provide some automation and cartographic enhancement (for example menus of geological "Features"; standard colour tables; automated map key generation). The graphic data are linked, via ODBC, to a Microsoft Access database. GeoGraphics® requires three tables: Feature table, Category table, and Map table. An additional geological table holds the attributes of the polygons. The polygon attributes include codes and descriptions for lithostratigraphy and lithology. These codes are linked to, and constrained by, the BGS Stratigraphic Lexicon, i.e. the corporate dictionaries held within an Oracle database management system. Once approved, the data are translated to ESRI ArcView® and MapInfo® formats for use within the BGS and to supply to external customers

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DigMapGB50 project priority and stability; and iii) ensuring the project was ring-fenced and adequately (if not generously) resourced. However, there are those who disagree with this assessment. They feel that the project did suffer from insufficient (and changing) priority relative to other BGS projects and also that supply of DigMapGB data to customers, internal and external, during its construction, served to delay the project.

6. SO WHAT'S NEXT? A variety of challenges remain to be faced, from the predictable and deceptively straightforward, ongoing updating of the map database to more subtle and complex future problems. 6.1 Improving DigMapGB 6.1.1 DigMapGB50 Version Two The next step is already underway, that is to develop an improved database - DigMapGB50 V2. In practice this means resolving the more intractable geological boundary and unit mismatches, addressing the "pragmatic" composite and undifferentiated codes in Version One and adding newly available data. It will also mean correcting the omissions and inadequate definitions in the underlying dictionaries (e.g. the Lithostratigraphic Lexicon). The experience gained in delivering Version One will simplify these tasks but they will still require substantial effort. It is vital that DigMapGB50 continues to be maintained and upgraded as new data becomes available. Resources will have to be secured for this against severe internal competition from equally important survey and research proposals. 6.1.2 Beyond Version Two Consistency within DigMapGB50 is a constant goal, but it is inevitable that new geological investigations and interpretations will change the spatial database and the underlying lithostratigraphic classifications and correlations. Robust procedures to continuously update the database have not yet been devised and implemented. Neither have we established exactly how we will quality control or "approve" the

future content of an ongoing seamless spatial database, which may ultimately hold many more attributes than a conventional paper map. The strategy for 1:10,000 scale data capture has already been described (5.2.2). 6.2 The future may be digital but……… There are many other subtle and less tangible issues that will need to be resolved. This section looks at a selection of those that the BGS feels are significant and the steps it is taking to address them. 6.2.1 Integrating other data Geological map data is only one information asset of a geological survey. How will we ensure that we can integrate the map database with all these other geoscience databases and add scientific (and commercial) value? Between 1997 and 2000 the BGS ran a project, geo-IDS (geoscience Integrated Database System), whose task was to address corporate data management issues, including this one. That work and the recommendations that flowed from it are now being taken forward as an established programme to ensure corporate and holistic information management within the new BGS structure. 6.2.2 Working in 3D and the field Now that the technology is available, shouldn't we move on and go for seamless digital workflows from field to user? Is modelling software mature enough for us to work in and add the third and fourth dimensions to the map data? Two major, linked BGS research and development projects have been instigated to tackle these two questions. The DGSM (Digital Geoscience Spatial Model) project started in April 2000 and is researching and developing best practice in 3D modelling. http://www.bgs.ac.uk/scripts/programme/project.cfm?proj=ESB96900080). Work on enhancing DigMapGB data is an early target. The SIGMA (Single Integrated Geoscience Mapping Application) project started in April 2001 and is tasked with developing an efficient total digital workflow for the geoscientist.

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8 ACKNOWLEDGEMENTS DigMapGB is a big project involving many people in the BGS. I would like to acknowledge my thanks to them all here. However, in putting together this paper Kevin Becken supplied a great deal of technical information and I am grateful to the following for their advice and assistance: Rob Armstrong, Jeremy Giles, Chris Green, John Laxton, David Lowe, Tony Myers and Alan Smith. This paper is published with the permission of the Executive Director, BGS. REFERENCES Becken, K, 2000. Digital map of Great Britain (DigMapGB) project description. Internal British Geological Survey Technical Report. Bickmore, D P and Kelk, B, 1972, Production of a multi-coloured geological map by automated means: Proceedings of 24th International Geological Congress. Ottawa, 1971, Section 16, pp. 121 - 127. Jackson, I and Asch, K, 2001. The status of digital geological mapping in Europe: Computers and Geoscience, in press. Loudon, T V, Wheeler, J F, and Andrew, K P, 1980. A computer system for handling digitised line data from geological maps: Computers and Geoscience no. 6, pp 299 - 308. Nickless, E F N and Jackson, I, 1993. Digital geological map production in the United Kingdom - more than just a cartographic exercise. Proceedings of the 16th International Cartographic Conference, Cologne. Rhind, D W, 1973, Computer mapping of drift lithology from borehole records: Institute of Geological Sciences Report no. 73/6, 12 pp.