A: Preface and Achievements of the Workshop.- 1. Preface.- 2. Achievements of the Workshop.- B: Definition of the Problem.- 3. Spatial data handling in the geosciences.- 4. 3-D modelling with geoscientific information systems: The problem.- 5. Geologic data handling.- 6. The role of the conceptual datamodel in software application integration.- C: Existing Three-Dimensional Geoscientific Information Systems.- 7. A spatial information system with advanced modeling capabilities.- 8. The DASDBS geokernal - an extensible database system for GIS.- 9. Three-dimensional solid modeling of geo-objects using non-uniform rational B-splines (NURBS).- 10. A mapping approach to three-dimensional modeling.- 11. GOCAD: a computer aided design program for geological applications.- D: Three-Dimensional Data Structures and Display Methods.- 12. Modeling natural objects via octrees.- 13. 3-D structures for the encoding of geometry and internal properties.- 14. Methods for the efficient storage of spatial geologic data.- 15. Key 3D modelling concepts for geoscientific analysis.- 16. Geometry for three-dimensional GIS in geoscientific applications.- 17. GIDBS: a database system for hierarchically represented gray-scale images.- E: Applications of Three-Dimensional Geoscientific Modeling.- 18. Applications of 3-D geoscientific modeling for hydrocarbon exploration.- 19. Two major problems in representing geological well data and seismic data in petroleum-bearing regions via 3-D geographic information systems.- 20. The application of new 3-D computer modelling techniques to mining.- 21. Applications of three-dimensional geoscientific mapping and modeling systems to hydrogeological studies.- F: Transcriptions of Conference Committee Discussions.- 22. Report of discussions by the computer scientists.- 23. Report of discussions by the geoscientists.- 24. Report of discussions by the members of national geological surveys.- 25. Report of discussions by the hydrocarbon interest group.- 26. Report of discussions by the minerals exploration interest group.- 27. Report of discussions by the environmental sciences interest group.- 28. Report of closing discussions.- Glossary of Terms.- Survey of Participants.- List of Participants.