Authors: Frank Arnott, IGM Ltd James Perrin, MVC
GeoExpress is a development of AVS Express for the Earth Sciences from IGM Ltd. The OASIS database is an advanced spatial database used mainly for managing and archiving Earth Science survey data. The database is part of a data processing and mapping package developed by Geosoft, Canada. Both products are used by mining companies, environmental, petroleum industries, government surveys, universities, and research groups.
The OASIS data sets are in spatial configurations suitable for geological and geophysical surveys. This includes random point data, line survey data, 2D gridded data and drill hole data. The data base was mainly designed for two dimensional spatial data but can contain a z spatial co-ordinate as a data parameter. 3D spatial data can be stored in this way, for example volumes can be represented as 2D gridded slices or drill holes as polylines with x,y and z co-ordinates.
The number of data components attached to each spatial node and represented as data columns in a database, can be large. Typical values range from one or two to a few hundred. A special form of data component called an array component can also be stored. This is used when a set of readings such as a tensor measurements or time dependant readings are taken at each spatial location. The resultant data component is stored in layers under the same column heading, effectively producing an array data column.
The databases can be large extending into hundreds of Megabytes and the storage is controlled by a number of archive options. These include optimisation for size or for speed of access. Geosoft provide an API for third party developers and a set of runtime libraries. Using this API, a comprehensive interface has been developed for importing and exporting data between OASIS and GeoExpress. The interface inherits as much control as possible from the database, allows filtering of data before import and is able to present data immediately in the GeoExpress Viewer.
To provide for all these possible variations of data mapping and additional cropping/filtering a well structured module and extensive UI needed to be constructed. Some of the design and technical issues of these interfaces will be presented.
Example applications will be presented from both systems and for those interested in more detail, both products will be available for demonstration.
References:
www.geosoft.com/pinfo/oasismontaj/index.asp
www.avs.com/software/soft_t/igm.html
October 2004