New Technology for a New Century
TWO STANDARDS ON DIGITAL MAPS AS PART OF THE HUNGARIAN NSDI
Dr. Szabolcs MIHÁLY, Hungary
Key words: digital map, map standards, cadastral map, topographic map, base map, structural standard, content standard, instruction, DAT, DITAB.
Based on the standardisation of geoinformation in frame of CEN TC 287 and partly ISO TC 221 and taking into account the Hungarian conventions as well as the Hungarian Law on Surveying and Mapping (1996) two standards on digital maps has been issued in Hungary last 4 years.
The first standard is the conceptual model on digital basic map (on multicadaster map) issued by the Hungarian Board of Standards nomenclatured as MSZ 7772-1:1997. The standard has been realised in life using also the digital base map instructions. The MSZ 7772-1:1997 standard and its instructions has been applied and proved fully appropriate for the practice during 3 years of surveying practice in the frame of the National Cadastre Program.
The second standard is the conceptual model of Digital Topographic Data Base. The Hungarian Board of Standards issue number is MSZ 7772-2:2000. Recently the connected digital topographic data base instructions are elaborated in draft. Next year digital cartographic database conceptual model is expected to be issued.
Requirements for the map standards have been formulated as
The international GI structural standard used too derive the Hungarian map data base content standards were those of CEN and ISO which got readiness to be used and which have been coincidancing to each other, namely: prestandards on spatial schema, quality, metadata and position.
Based on selected international structural GI prestandards two Hungarian content standards on map databases have been defined as it follows below:
The DAT- and DITAB-Standards are describing the conceptual model: Terminology, Data model of digital base map, Position (Map projection system, Reference, Height system), Classification of objects and thematical structure, Spatial schema (Geometrical primitives, Topological primitives, Spatial view), Attributes, Relations (between nodes, between edges, faces and rings), Data quality (Source, Extent of application of data, Quality of geometric data, Quality of attribute data, Actuality, Completeness, Consistency of data, Technology for data collection, Data protection, Verification).
The digital maps are represented in object-oriented relational database. The specific objects are described by their attributes, relations and data quality parameters. At conceptual model level the specific objects are represented by their generic objects. Objects with common attributes are grouped into one object group. The object groups having common attributes at higher level are grouped into one object classes. The attributes, relations and quality parameters are defined in the standard as generic. Their values are given in supplementary instructions.
Three object types are distinguished by its geometry: point, line, surface objects. The objects are managed by their topology such that fulfilling the full-topology requirement. The topology elements distinguished are: node, edge and face. The nodes are divided into more specific types. By geometry, the digital base map databases are 2-dimensional with planimetric coordinates. The hights are or can be given as attributes.
The "Thematic Structure", the "Object Classification" and the "Example Attribute Table" are annexed, for the DAT-Standard and for the DITAB-Standard. In the DITAB-Standard the objects and attributes are harmonised with the DAT-Standard as well as with the DIGEST standard for NATO-compatible actions of the Hungarian Defence Forces.
Dr. Szabolcs Mihály
24 March 2001
This page is maintained by the FIG Office. Last revised on 15-03-16.