THE SPANISH OFFICIAL 1:25.000 CARTOGRAPHY: MILESTONES, ACHIEVEMENTS AND NEXT LEAPS FORWARD

Lorenzo García Asensio Instituto Geográfico Nacional de España (IGN-E)

Gral. Ibáñez de Íbero, 3, 28003 Madrid, Spain Tel.: +34 915979589 Fax: +34 915979765

E-mail: lgasensio@mfom.es

ABSTRACT In 2003 IGN-E has completed the 1:25.000 cartographic coverage MTN25 complying with one of the main assignments as Spanish NMA. The production of this series has been really increasing in the last ten years because of a continuous IT invasion inside the production processes. In addition the new methodologies have allowed to get a 25m grid DTM, MDT25, and a GIS oriented dataset BCN25. These suite of products are the most precise and homogeneous series covering Spain. We compile here those milestones and achievements succeeded within its production period that yielded heavy or long consequences, as well as the most important characteristics of the completed series and its current updating line. Finally we point out the next leaps IGN-E is foreseeing as short-term objectives: implementation of a GIS mainly to integrate all 1:25.000 data within a unique system, unifying updating processes, and helping its exploitation in the Spanish SDI. 1. HISTORYCAL ASPECTS. THE NATIONAL TOPOGRAPHIC MAP OF SPAIN.

In 1870 IGN-E began the production of the National Topographic Map of Spain at 1:50.000 scale, MTN50 (Mapa Topográfico Nacional 1:50.000). The long and hard project culminated at latest 60th leaving behind a lot of matters as result mainly of the continuous changes were affecting to the cartographic techniques. From 1975 map updating was making at the same time to the production of a new series at 1:25.000 scale, MTN25, with the proposal of complement MTN50 in some areas of special interest. However, in the 80th this new series became a national coverage project too. The strong impulse given to this new and wide project caused a consecutive reduction of the resources applied to MTN50 conservation, but considering the subsequent high benefits would be got from the new map availability (Figure1). In 1985 a new Spanish law named Cartographic Ordering Law (Ley de Ordenación de la Cartografía) qualified the old stager project MTN25 as State Official Basic Cartography, and assigned its production and conservation to the IGN-E, something that really was happening. Just a year later, as an only apparent cause/effect relation, IGN-E began the adaptation of its photogrammetric equipments to capture rough spatial data in digital media. The following years were very important to guide the cartographic production procedures toward the new information technologies lines. In 1988 IGN-E introduced a plotting and edition system that allowed to prepare and laser-film automatically the originals for offset printing using directly digital cartography files. Next year a wide project to capture 3d photogrammetric data began, yielding in 1993 new digital information availability inside more than 2000 MTN25 sheets. Just this fact increased the DTM production named MDT25 (Modelo Digital del Terreno 25x25m), promoted only a year before, and performed by ASCII matrixes realizing 25x25 meters height grids to each MTN25 map sheet. DTMs were computed from contour lines a spot heights using complex kriging methods [1].

Figure1: MTN50 and MTN25 sheets geographical distribution. However processes following data capture were not still advanced in a IT direction, so map production remained too slow. As a consequence, from the beginning of the MTN25 project in 1975 to 1993, there only were a 40% published map sheets. 1994 realized so strong technologic advance that in practice it happened a sort of crack in the MTN25 history. Essential parts of the production chain were transformed to digital procedures, as selection, updating and edition processes. So the whole project began to be executed as a consecutive set of digital procedure (except, obviously, field works). Soon some effects of that were strongly noted: firstly production increased by a factor of 4 comparing the production average ratio in both periods before and after 1994. On the other hand, MTN25 became a digital series from then, meaning a very relevant fact from any point of view, mainly considering next exploitation possibilities [2]. In 1997 a new series named Numerical Cartographic Data Base BCN25 (Base Cartográfica Numérica 1:25.000) started to be designed, as a derived product from MTN25, in order to get the 1:25.000 cartographic information complying a kind of structure to allow data loading and exploitation inside GIS frames. Therefore BCN25 holds the MTN25 information with added geometric and topological properties, as we will see in point 2, and an specific DB oriented geocoding instead of the original graphic oriented codes. Nowadays MTN25 and BCN25 series (and BCN25�s altimetric complement MDT25), with more than 4100 units/sheets each one, offer a complete coverage of Spain, realizing continuous and homogeneous vectorial data of the whole territory represented with 3m accuracy, with contents of topographic cartography for a lot of different uses. That is also permitting, since 1999, to get a new digital MTN50 series using computer assisted cartographic generalization methods, with an unthoughtable efficiency in the years that the ancient version of this series constituted the first State Official Basic Cartography. The current conservation lines affecting MTN25 and BCN25 series are also being reopened to be adapted, as later is described, to a deep modification of our National Cartographic System, which consider the updating of our Official Basic Cartography as a shared and decentralized project by the cooperation of the Autonomous Governments in Spain.

2. CURRENT COMPOSITION AND TECHNICAL CHARACTERISTICS OF THE SPANISH OFFICIAL BASIC CARTOGRAPHY AT 1:25.000 SCALE.

State Official Basic Cartography in Spain consist of, as viewed in last point, MTN25, BCN25 and MDT25 series. We also consider a part of it 3d captured data series, coming from the beginning of the production chain, and traditionally MTN50 obtained from MTN25 by assisted generalization (although for that reason it is not really basic cartography). We are going to describe the most important characteristics of MTN25 and BCN25.

General characteristics. The contents of both series are the typical ones considered in topographic cartography at near 1:25.000 scales, that is, relief, hydrography and land uses as physical geography themes, and populations, buildings, natural resources, industry, communication routes, administrative boundaries and bench marks as human geography themes. We don�t forget, of course, the exhaustive and indispensable toponomy and text rotulation (Figure 2).

Figure 2: Covers and details of a MTN25 sheet. Data model has a two-dimensional vector design and spaghetti structure. Data are stored in DGN files of Microstation tool, each one of them collects information about one geographic distribution unit, a map sheet, covering a nominal area of 10� latitude by 15� longitude. Relief is represented using 10m equidistance contour lines and spot heights. Heights of both kinds of elements are inserted in the graphic group of the DGN format [2]. Georeferencing. In the following table data regarding to georeferencing of both series are shown. As soon as possible we will change ED50 system to ETRS89 as European agreement.

Data coding. The table of MTN25 codes assign to each element a set of parameters (level, colour, weight and style) which describe DGN symbology in a biunivocal way. It includes codes, which we call �visual codes� (over 200), of elements used only for the correct data visualization and plotting. BCN25 coding table expands the MTN25 one to around 800, although visual codes are not included. Besides BCN25 elements are grouped together in homogeneous classes which are linked to a unique six-digit geocode (TTGGSS). The first two digits show the �theme� discriminating between the most general aspects of the information. The second couple of digits show the �group�, matching each one of them to an entity inside each theme. The last two digits are the �sub-group�, pointing possible variations of each entity. This geocode is linked in such a biunivocal way to a DGN symbology code [3] . BCN25 data structure BCN25 series has, as it can remembered from point 1, other topological and geometrical properties which allow their a direct loading and exploitation inside a GIS. The conceptual model is based in the �element� concept, that is, a part of an entity maintaining both continuity and uniform cartographic representation inside a MTN25 sheet, and owning a particular name (if it exist). As examples we have a river, a road or a population. Elements can be, as typical, a point, a line or a surface. The name of each element is assigned using a text which origin fit in one vertex belonging to the element geometry. It does not exist nodes in BCN25 as spaghetti structure does not consider them. However, when two or more elements intersect, the crossing point is computed and included as one of the vertex in each element geometry. This permits to identify nodes without additional calculus, but only finding vertex defined by identical coordinates in different elements geometry. Quality Metric accuracy is considered near 3 meters both in planimetric and altimetric data. semantic accuracy and completeness are considered near 96%. Besides BCN25 homogeneity is guaranteed by an independent part of the chain production which assumes revision and quality control works [3]. Use of basic cartographic series concerns applications which need a partial or complete State metric infrastructure. So it is the best data source to derive digital and analogical cartography. Its applications cover some technological activities as mobile phones, locations, environmental and engineering simulations, GPS referencing, traffic happenings, optimal routes, business analysis using administrative boundaries, works preliminary plans, etc. 3. PRODUCTION PROCESSES. RELEVANT MILESTONES WITHIN LAST TEN YEARS EVOLUTION. Since all MTN25 production processes were completely computerized, in 1994, the immediate and unique aim was to cover Spain as soon as possible. Production chain begins with a colour photogrammetric flight at 1:40.000 scale including GPS aerial surveying. The followings three tasks, that is, photogrammetric surveying, aerial triangulation and 2D/3D data capture allow to reach over 2,5m accuracy. Next processes are cartographic compiling/selecting data (or updating if the map sheet already exists), which includes field research works, cartographic edition and quality control. After last one a digital version of each map sheet is completed. Compiling/selecting phase complete the information which must be included inside each map sheet and identify its elements. We must stress that field works allow not only to complete photointerpretation tasks and additional data captures, but constitute the main source to gather and check a vast toponomy, which is indispensable to make the map really useful. This phase is made by means of the IGN Regional Services distributed around the Spanish territory. From cartographic edition process data fits some generalization and symbolization conditions to satisfy MTN25 cartographic edition standards. This phase, as well as part of the previous one, is made using automatic and interactive tasks ad hoc developed by IGN-E [2].

Quality control not only guarantees a minimum standard of cartographic quality, but also an extended homogeneity to the whole series. This is an specially important aspect taking into account that, as mentioned before, a part of the production chain operate in regional offices. In 1995 IGN-E began to introduce digital photogrammetric stations which first duties were quality control of 3D data capture. At present IGN-E has 35 of such stations distributed by its central andfregional office, making not only quality control tasks but also photogrammetric 2D/3D data capture. Although BCN25 design starts in 1996, its production did not really begin till 1998. The additional applied processes to finished MTN25 sheets consist of geometric and consistency edition, BD geocoding, names assignment and intersections computation. So these new 1:25.000 data can be then automatically loaded and exploited inside a geographical information systems. Name assignment is an specially important process, as described in point 2, because it involves long and hard work but provides needs to most applications. Figure 3 represents the complete chain with every process applied to produce the Official Basic Cartography Series.

Figure 3: Production chains working for Spanish Official Basic Cartography series.

In 1999 MTN25 execution is advanced enough to start a new digital MTN50 production by means of automatic, semiautomatic and interactive generalization processes which were developed by IGN-E on purpose [4]. Besides in that year digital terrain model MDT25 was completed (its production began in earliest 90th , see point 1), consisting of a 25x25m grid computed from 1:25.000 altimetry. BCN25 and MTN25 execution status in 2001 forces strongly to start a systematic updating programme affecting both series. Finally in 2003 MTN25 coverage was completed, and we hope to complete also its twin series BCN25 this year 2005. 4. A NEW SPANISH 1:25.000 GIS AS NEXT LEAPS FORWARD. TARGETS AND FUNCTIONAL ASPECTS.

Although ending of basic cartography series at 1:25.000 scale constitutes itself a cartographic milestone in Spain, current productive structures keep an strong link to each produced series. As a consequence, although primary rough data are common to all of them, its updating processes are really independent in practice, so there is some risk of incongruity appearance. Because of that in 2004 an ambitious project to develop an advanced 1:25.000 GIS has been started. This project rises with a new Strategic Plan launch in IGN-E which also consider new Territory Observation Plans in Spain at different resolutions (see [5] as a good example). This 1:25.000 GIS project, named BCN25 3D, presents two very important novelties. Firstly the new system will be the unique intelligent container of the State Official Basic Cartography in Spain, causing updating processes unification, and insuring its exploitation supplies products and services (in special cartographic series) which are consistent from the both updating and contents points of view. In the second hand observation, production and updating works will be made in a cooperative and decentralized way with the participation of different State Departments and the Autonomous Governments within Spain. Therefore

geographic information coverage are obtained in a consistent way (because its common origin), avoiding to duplicate actions in some geographical areas and, of course, optimizing economic efforts. Besides these two new strategic guidelines allow IGN-E to approach the current European and international policies in regard with Spatial Data Infrastructure (SDI), as the INSPIRE initiative from de European Commission. BCN25 3D project expect, at the first place, to compose MTN25 and BCN25 series to unify its updating and data extraction processes, and preserving the ability to regenerate the original series (and also new other ones) without interactive operations as possible. So we will optimize efforts and insure products and services consistency. Besides BCN25 3D will try to expand benefits realizing complex queries, data edition, spatial and thematic analysis, web services and publications, generalization assistance, etc. One of the most risky operations will be initial data loading in the GIS because it involves a vast data handling just at the same time previous production chain will turn stopped. Effects of that situation must be carefully foreseen and controlled (Figure 4).

Figure 4: Migration from 1:25.000 series to BCN25 3D GIS. DBMS is being Oracle and Geomedia is going to be the GIS tool to realize data management, updating and exploitation. This tool keeps a total interoperability with the current productive environment in IGN-E, in such a way we will be able to avoid drastic changes when the new interfaces and procedures be introduced. Besides connection support between Oracle and Geomedia exist from both products, making easy a client-server architecture establishment. Data model which is currently been developed to manage 1:25.000 series information, consider a full topological design: entity (point, line and surface), arc/entity variation, node, geometry, toponomy, attributes, symbology, genealogy and quality (metadata). It will include hypertext elements and definition, attributes and relations of raster objects. It will try to have the ability to provide, without any modification, generalization assistance to derive MTN50 series. As a new, with regard to the original series, data model offers a 3d description of the whole cartographic information maintaining kept topological integrity. 5. REFERENCES. [1] L. García, J. Lumbreras, G. Martín-Asín and C. Robles, �La altimetría en el S.I.G. del I.G.N.: Modelos digitales del terreno", MAPPING núm. 8, pp. 36-38, Madrid (1992). [2] J. Cebrián and L. García, �La Cartografía Básica Oficial de España: El Mapa Topográfico Nacional a escala 1:25.000� VI Cartographic Regional Conference of the United Nations for America, New York (1997).

[3] A. F. Rodríguez and G. Martín-Asín, "La Base Cartográfica Numérica 1:25.000 (BCN25)", VII National Congress of Topography and Cartography, TOPCART 2000, Madrid (2000). [4] L. García, �Procesos y proyectos de generalización cartográfica en el Instituto Geográfico Nacional de España�, IV Technical Meeting of the Cartographic Standards Commission, Geograhic High Board of Spain, Barcelona (2004). [5] A. Arozarena and G. Villa, �El Plan Nacional de Ortofotografía Aérea de España�, VIII National Congress of Topography and Cartography, TOPCART 2004, Madrid (2004)

THE SPANISH OFFICIAL 1:25.000 CARTOGRAPHY: MILESTONES, ACHIEVEMENTS AND NEXT LEAPS FORWARD

Lorenzo García Asensio Instituto Geográfico Nacional de España (IGN-E)

Gral. Ibáñez de Íbero, 3, 28003 Madrid, Spain Tel.: +34 915979589 Fax: +34 915979765

E-mail: lgasensio@mfom.es

Short CV

- 1982 MSc degree in Mathematics (Astronomy and Geodesy) from the Complutense University of Madrid.

- 1985 Geographical Engineer in National Government.

- 1989 Head of Geographic Information Department at the National Geographic Institute of Spain.

- 1992 IT civil servant in National Government

- 1992-94 Spanish Delegation member to CEN/TC 287 committee "Geographic Information�

- 1994 IT assistant deputy director of the National Geographic Institute of Spain

- 2001 Advanced Studies Diploma (DEA, previuos PhD degree) in IT engineering and Automatics from Distance Learning National University.

- 2004 Assistant Director of the IGN-E for Cartographic Production

- Past member of the Geodesy and Astronomy Institute (belonging to the Scientific Researches High Council and Complutense University of Madrid) as investigator grant holder.

- Former secretary of AEN/CTN 148 committee "Información Geográfica Digital" in the Spanish Standards Body

- Professor in some courses in Universities and other Public Institutions.

- Over 30 publications and conferences