86 Abstracts

GIS database model for geological maps

Tudor G. 1, Gheuca t. 1 Geological Institute of Romania, 1, Caransebes St., Bucharest, Romania

After the GIS (Geographic Information System) systems appeared, most of the countries started to build-up spatial databases which provide the possibility to process the geological data (spatial and descriptive), while the technological evolution leaded to a permanent adaptation (Richard, 2003). In the past, the GIS systems would use proprietary storing formats, which would contain spatial data and attributes in separate files (coverage, shapefile).

Recent1y, ESRI (Environmental Systems Research Institute) has developed the geodatabase concept in order to store spatial and attribute data in c1assic database management system (RDBMS). By using MS Access (personal geodatabase) or MSSQL Server, Orac1e database type (enterprise geodatabase), geodatabase stores data in point, line, polygon (feature c1asses) types of layers, logically grouped in data sets (feature datasets). Possibilities have been added to establish rules regarding data validation, relationship and topology, in order to thus maintain the data integrity (MacDonald, 200 1).

By realizing a model, the existing spatial data (digitalized using CAD type products) or created using GIS systems, can be integrated in the geodatabase with options for an efficient administration, for a reutilisation within diverse projects or for a future development within an integrated database.

The realization ofthe spatial database model contains especially the following main components: - objectives, existing data analysis and entities establishing; - realizing the database model; - establishing the database integrity rules (relations, topology, subtypes, domains). The analysis ofthe data ofthe geological map content provides a series of elements, which are separated in data sets and

layers, organized within a map sheet: - geological contacts: geological units limits (normal or discordant), eruptive rocks contacts; - the faults that shift the geological contacts; - the geological units, limited by contacts and faults; - major geological units types, which overlap, on the map, over the geological units (flisch, volcano-sedimentary formations, major rock types); -linearly represented rock levels (limestone, amphibolites intercalations); - observation points accompanied by descriptions or measurements (structural, geochemical, geophysical); - topographic elements: rivers, lakes, localities, roads, railroads, contour lines, peaks; - associated elements: legend, geological ~ections, stratigraphic colurnns, tectonic drawing, source mlţterials .

The information's source consists of geologic al maps sheets, scaled at 1 :50.000 printed by the Gt

Poster

f-. -----f~ --------------------------: ;:... I=" 1::'" =" ;:", I="

I~ ~ 1:

,-----

-::; --~ ~ .... ~ ,.

87

I

r-+---1:1-- "",- r------ r--------- -------- f---------- 1------------_·

I t ~- -~--~-1"' 1"""",, 1"''''''''' 1"' """""" ..... I- I"' 1 1"""'"

' il .J~ 1'" :!=" 1"" :!=" ::-

~~ .-.-. 1:::':-'-

11Ek:- I~ c--..._ --E=== ------- ----------- ------------------------- ---r

"",.e.;,;;;;p- ---------------------r.:;= _

~ "' 1""""" 1"' ll&IWIl i';:;'~ "'QII.W:lIIl ;::-- r-r= ;- I ~-,- I~ ~ ~ ~--

IYM8OI. Iv.oI.. ::;,.... t_

'"""" '"""" - --'- ,--E I "'~ :;:::.:., '--~ --------------------------Fig. 2 . The logical spatial database model (fragment).

. ....-- --l:f

-' --:: ....... -.......... -----,

Fig. 3

, '1 ' , . .

The physical spatial database model (fragment) .

= ._---

- The logical model configures the previously established concepts in tables, attributes and relations, in relational databases, but independently from the software platform to be used (fig. 2). On this base, the structure ofthe database will be physically established. The entities naming convention is to start the name with the indicative of the map sheet, followed by the initial letter of the data set, necessary for an eventual extension into an enterprise type integrated database. - The physical model represents the database design itself, as a representation which takes into account the facilities and enforcements provided by the management system of the database. Basically, it contains ali the tables, attributes, relations (as elements of a classic database), accompanied by specific geodatabase elements (such as geometry, data sets, spatial reference, subtypes, domains, topology). Fig. 3 shows the constitutive elements of a main entity ofthe physical model, Glimits.

The data sets contain grouped layers which have the same spatial reference, associated with rules that establish the relations and the topology:

- main data sets (geologic and topographic elernents): Geology, Basemap - associated data sets (the components associated with the geologic al map): Legend, Tectonics, Columns, Sources, Section12.

The tables with attributes are contained separately, within the geodatabase and they contain simple classifications ofthe classes of objects needed for symbolisation (colours, hatches, lines, points). On basis of a field which can be found within ali entities, where it represents an external key, there have been established l-m type permanent relationships, within the database.ln order to classify in symbol types, there was used the "join" facility, which combines the attributes from each entity with attributes from associated tables.

The component layers of the data sets correspond to real elements, separated within the map (Glithology, Glimits, Gsuperimposed, Grocksigns, Gmaparea, Bstreams, Broads, Blocalities, Blakes). On the map, these elements represent the geological units, contacts (geologicallimits and faults), superimposed formations, rocks intercalations, rivers, roads, localities, lakes. The associated data sets contain generic layers of polygon, line, point and text types, in order to represent the corresponding elements on the map.

For a better administration of the database, there could be established subtypes and domains. The subtypes could be found within the Glimits entity, in order to separate two main types (limit and fault), which have different rules within the data set topology. The domains that are used to establish the valid values list of a field, have been created in relation with the external key field, which establishes the code and then the symbolisation is differentiated.

The topology is represented through the spatial relation between the objects that share the same geometry (limits, geological units), within the data set layers. The imperfections resulted from the vectorizing term with CAD are corrected (gaps, slivers, dangles overshoots and undershoots).

88

... ", ....

Fig. 4

-""""""'" ... :=. ...

I

,-. .!!=:--- -._'-'-'--'-'_0_0 __ "'-

Abstracts

ROMANIA 40 b ZECe HOTARE wo-.. 1Wt'll'_~ "'" ---

I =-

= =-

Geological map sheet sample. scaled at 1 :50. 000.

In tbe end, the topology rules conceming the main fields (Glitbology and Glimits) are the following:

- Glithology must not overlap, must not have gaps, boundaries must be covered by lines from limits;

-------===.,.= ----::.:::-----.-----:::::-----====.---==-. ------==---. ~:.:.:-- -_ ":"'..=.=-..:::.-----=-== :=~-_.""!'=------ ------ ----- =--==--=-- -----! ;;=='=::":::.. -------'=

........ --====t==r-----==------1-

- Glimits must not overlap, must not intersect, must not have dangles for subtype limit, must not self intersect, must not self overlap. The labels associated with the objects on tbe map are to be found in special fields or in separate layers, which can be

transferred in annotations.

The representation ofthe spatial objects by means of some standard symbols have as a result, witbin a GIS, tbe realization of a geological map (fig. 4), associated with auxiliary elements (legend, geologic al sections, tectonic drawing, stratigraphic columns). By realizing the geodatabase model there was created a frame for the administration of the spatial data witb the purpose of creating the geological maps. The model will be developed and improved, in order to continue the creation of geological maps and in order to establish an integrated database.

Bibliography

Environmental Systems Research Institute (ESRI) Inc., ArcGIS (ArcCatalog andArcMap), http://www.esri.com. MacDonaldA. (2001), Building a geodatabase, Independent Publishers Group, l-st edition (July 200 1), 492p. Michael Zeiler, Geodatabase Diagrammer, Environmental Systems Research Institute (ESRI) Inc., http://arcscripts.esri.com Richard S. M. (2003), Geologic map database implementation in tbe ESRI Geodatabase environment, in Soller, David R. , Ed., Digital Mapping Techniques ,03-Workshop Proceedings, U. S. Geological Survey Open-File Report 03-471 , p. 169-183, http://pubs. usgs. gov /0f/2003/ of03 -471 /richard2/index. html.

RJ Mineralogy 840085RJ Mineralogy 840086RJ Mineralogy 840087