IAMG 2001--Cancún Technical Program--Session I

Home Page Technical Program Session I Intro Session I Papers

Geologic Data Transfer Using XML by Simon J.D. Cox, CSIRO Exploration & Mining, Australia XML is emerging as a standard for structured-data transfer. The self-describing clear-text file-format is also a prime candidate for archival use. However, XML is a meta-language for the construction of a language useful for data. The actual tag-set and structures must be defined for each particular application, such as geology. Schema definitions (using e.g. DTD, XSDL, Schematron) are the formal representation of the tag-set. Developing the tag-set thus requires design of an application-domain data-model, which is then serialised as a schema document. A general data-model for geospatial information has been developed and standardised through ISO. This object-oriented "feature" model is a good match with the classic approach to geology, allowing focus on named objects such as "fault", "sample" or "reservoir", but also extended or compound features like "image", "survey" and "model". The feature model suits a database-oriented datastore, in contrast to the conventional map-oriented "coverage" approach. If we develop our geology-specific models to conform to the feature model, we can expect to maximize our potential use of future generic DBMS, GIS, CAD and graphics software. An XML encoding of the model, the Geography Markup Language (GML), has been developed through the OpenGIS Consortium's (OGC) implementation program. GML provides generic components for the description of "features", including geometry and patterns for building application-specific feature-types. Thus, an ISO compatible XML encoding for geologic data is constructed as an "application" of GML. We are developing an XML representation called the eXploration and Mining Markup Language. We have drawn strongly on existing models, particularly drawn from industry and statutory agencies. Modeling and XML development has also drawn on experience of the Petrotechnical Open Software Corporation (POSC). The ISO Feature Model directly supports a simpler view of the world than the NADM model for geologic map data. For example, a feature-type, defined in a schema document, prescribes the property-set of each object within the application domain. Feature properties are tightly bound to features in a composition association. These provide an effective representation of a (denormalised) snapshot of data or a model for transfer between schema-aware applications. But these characteristics may conflict with a more scholarly approach, in which classification is subsequent to description, and may also be modified in light of later discoveries or conceptual developments. Applying the Feature Model in this context may require that NADM objects are represented as looser associations between weakly-typed "features" constructed at a more fine-grained level. Paper in PDF format Cox, Acrobat PDF, 504k.