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A Simple Data Structure for Earth Science Model Visualisation NIEeS Visualisation Workshop 29/1/03

A Simple Data Structure for Earth Science Model Visualisation NIEeS Visualisation Workshop 29/1/03. John Laxton. Outline of presentation. What is the Digital Geoscience Spatial Model (DGSM)? Outline of the Geoscience Spatial Framework (GSF) data model

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A Simple Data Structure for Earth Science Model Visualisation NIEeS Visualisation Workshop 29/1/03

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  1. A Simple Data Structure for Earth Science Model VisualisationNIEeS Visualisation Workshop29/1/03 John Laxton

  2. Outline of presentation • What is the Digital Geoscience Spatial Model (DGSM)? • Outline of the Geoscience Spatial Framework (GSF) data model • Outline of the spatial feature/attribute data model • DGSM metadata • How the GSF will work • Status

  3. DGSM Vision The DGSM will encapsulate BGS’ knowledge of the UK and its surrounding continental shelf. It will foster a model-centred ethos within BGS, in which all geoscience disciplines will contribute to and continually enhance the development of a set of multidimensional, coherent integrated geoscience models.

  4. What is the DGSM? The DGSM will consist of: • 3D models of the subsurface at a range of resolutions • Models showing different aspects of geoscience including: • Lithostratigraphy • Hydrogeology • Engineering and geophysical properties • Geochemical character • Links to other information including: • Text descriptions • Images and movies • Statistical analyses • Information on the modelling process

  5. What is the DGSM for? The primary objective of the DGSM is to make digital geoscientific information available as part of the strategic remit of BGS and for it to become the central repository of geoscientific knowledge in the UK. It has been described as the extension of the geological map into 3 dimensions. The DGSM will also allow the integration of data and aid the development of understanding of the geology of the UK.

  6. What is the geological map for? • It represents BGS’ current best interpretation of the geology of an area • It is publicly available • It is used as the basis for developing added-value products

  7. How is geological spatial modelling done in BGS? • Use a range of commercially produced modelling software • EarthVision • GoCAD • Vulcan • Landmark • Models can only be used with the modelling software that generated them • This conflicts with DGSM aim of making models widely available

  8. DGSM Models (1)

  9. DGSM Models (2)

  10. What is the aim of the Geoscience Spatial Framework? • Design, implement and trial a format for holding digital models that: • is independent of the originating software • can feed visualisation applications, including over the web • will preserve the models as modelling software and proprietary formats are upgraded

  11. Geoscience Large Object Store (GLOS) • The GLOS holds models in their original software formats • Full richness of original model in GLOS, but at present can only be viewed on a workstation with originating software • GLOS dependent on originating software version

  12. The GSF and GLOS - How do they relate? • Loss of model richness and visualisation capabilities with GSF • GSF main vehicle for external dissemination via web – ‘the new geological map’ • GLOS used for internal model exchange, integration and development • GSF and GLOS are complementary

  13. GSF Design (1) • Identified the output from current modelling projects – the input to the GSF • Identified the geological sequences to be handled • Base design on modelling package export formats – points on a surface • Describe rock bodies above/below surfaces • Software to regenerate connectivity

  14. GSF Design (2) • Link to BGS corporate feature/attribute model for full object attribution • Link to metadata for track-back to data and to model inference/reasoning • Link to ‘surface identifier’, which will also link to GLOS

  15. Geological sequences

  16. GSF Data Model (1) • GSF data model holds surfaces (and volumes) as points • Each surface point has up to three ‘aspects’ (above, below, at) • Each aspect at each point can link to one or more features (eg a surface could be a unit boundary, and a fault, and a mineral vein) • The features and their attributes are defined by the spatial feature/attribute model • GSF data model is spatially simple but attribute rich • GSF data model closely linked to corporate data model and extensible

  17. GSF Data Model (2) • One XYZ record for each GSF point • Each XYZ record links to any number of aspect/feature records • Each GSF aspect/feature record links to a record in the spatial feature/attribute tables • Option to define surfaces explicitly • Option to link GSF points directly to individual attributes

  18. Spatial Feature/Attribute Model (1) • Geology Extent • Geology Boundary • Unconformities (major named) • Linear Landform • Areal Landform • Landform Point Observation • Structural Composite Feature (includes faults, folds etc and links to structural database) • Structural Point Measurement (links to structural database) • Contours

  19. Spatial Feature/Attribute Model (2) • Non-oriented point data (links to existing databases such as FOSSLOCS or BRITROCK) • Major Mineral Vein • Boreholes • Major structural element (larger scale than ‘Structural Composite Feature’) • Palaeogeological Terrane • Modelled Geophysical Property Extent • Hydrocarbon Field Extent • Tectonic Plate Extent • Tectonic Plate Pole of Rotation

  20. Spatial Feature/Attribute Model (3) • Geology Extent • Attribute fields: ID; type; lithology; lithofacies assemblage; depositional environment; lithostratigraphy; seismic stratigraphy; sequence stratigraphy; biostratigraphy; chronostratigraphic age start; chronostratigraphic age end; chronometric age; chronometric age error range; method of detection; alteration type (including contact and regional metamorphism); alteration age; comments. • Usage: ‘Type’ covered by Geology Extent are: Solid Geology, Drift Geology, Artificial Ground Extent, Mass Movement, Geophysical Horizon e.g. base Permo-Triassic reflector, Limits of Source, Limits of Seal, Limits of Reservoir

  21. DGSM Metadata • Metadata about the data and sub-sets defined from it • Discovery metadata about the models • ‘Inference’ metadata linking the model to the data and processes upon which it was based

  22. Data sub-sets Data sub-set definition includes: • Date of creation of data sub-set • Inclusion criteria • Reasons for inclusion criteria • Exclusion criteria • Reasons for exclusion criteria Statements for whole data sub-set and individual records where latter depart from the general

  23. Discovery Metadata for Models (1) • Includes: • A statement of the overall scientific rationale of the model • A statement of overall model purpose • 3D spatial referencing system, areal extent and bounding coordinates • The introduction of a hierarchy of models

  24. Discovery Metadata for Models (2) • More rigorous use of existing ‘Quality’ fields, including use of DGSM dictionaries • Quality suitability (overall quality flag) • Scale/resolution validity • Usage/fitness for purpose

  25. Inference Metadata (1) Refers to metadata linking a data sub-set to a model or model component • Two key components of inference metadata: • Process description • Process quality

  26. Inference Metadata (2) Process description: • Interpretation • Interpretation confidence • Assumptions • Assumptions confidence • Interpolation/modelling process • Interpolation/modelling process confidence Statements for whole data sub-set and individual records where latter depart from the general

  27. How the GSF will work (1) DGSM Modelling Software (eg Earthvision) Export format (xyz points) GLOS DGSM Metadata population (Oracle)

  28. How the GSF will work (2) Export format (xyz points) GSF attribution application (ColdFusion) GSF loading application (SQL Loader) GSF points and attributes (Oracle)

  29. GSF Input Interface • Two applications built: • ColdFusion application to allow geologists to define features to be linked to GSF points • SQL*Loader application to populate GSF tables • At present work against complete EarthVision surfaces • 345,000 points loaded to GSF for surfaces from three models (S Downs Chalk, Cheshire Basin & Humber) • Applications being revised to incorporate feature/attribute model

  30. How the GSF will work (3) DGSM Metadata (Oracle) GSF points and attributes (Oracle) Attribute retrieval Spatial retrieval Metadata retrieval Model selection Retrieved set of GSF points

  31. How the GSF will work (4) GSF attributes (Oracle) Retrieved set of GSF points Triangulation application VRML generation FracViewer (?) Exchange3D (?) Web VRML Viewer Web Viewer (??)

  32. Design and develop output applications (1) • Outline design specification has been drawn up • Spatial selection interface • Metadata selection • Attribute selection • Individual model selection • Output/visualisation selection

  33. Spatial Selection Interface

  34. Visualisation options • Mesh/skeletal surface • Rendered surface • Block model • Point cloud • Cross-sections • Export formats eg VRML and XMML

  35. Design and develop output applications (2) • Report on visualisation technology options • FracViewer software seems best – but requires some further development • Alternatives include VRML and Java • Small application produced to triangulate GSF data • Triangulated data has been imported to a test copy of Fracviewer and successfully visualised

  36. FracViewer visualisation

  37. Four surface GSF output via VRML

  38. Status (1) • GSF data model designed and implemented • DGSM Feature/attribute logical model agreed as core of BGS feature/attribute model • Feature/attribute model being implemented – completion end March • Version 1 of GSF load applications used to populate GSF with trial data • Version 2 of GSF load applications, with link to feature/attribute tables, will be built early 2003/04

  39. Status (2) • GSF retrieval application being developed • GSF triangulation program implemented • GSF gridding program implemented • FracViewer investigated and discussions with Fractal Graphics and other vendors on development of a web viewer • VRML output from GSF triangulation

  40. Future Work • Version 2 of GSF load applications to handle feature/attributes • Handling input from full 3D modelling packages eg 3D Earthvision • Handling of model delimiters (such as holes) • Handling of complex surfaces • Population of attributes that vary over a surface (eg younging) • Development of alternatives to VRML

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