CompositeDB

For some use cases, it is advantageous to combine two spatial databases into one. For example, you may want to combine elastic properties from a seismic velocity model with viscoelatic properties. Rather than creating an entirely new spatial database with elastic and viscoelatic properties, a CompositeDB allows you to combine the spatial databases with elastic properties with a separate spatial database with viscoelastic properties.

Another case when a CompositeDB is advantaneous is when the fields within a spatial database have different layouts of the points. SimpleDB and SimpleGridDB both require the same layout of points for all values, so you cannot specify different layouts of points for different values. However, you can use a CompositeDB to combine spatial databases with different point layouts. For example, in specifying elastic properties the density might vary with depth, whereas the shear modulus varies in both the horizontal and vertical directions. In such a case, you could use one spatial database with a set of points in the vertical direction for the density and another spatial database with a set of points distributed in a volume for the shear modulus.

Warning

The current implementation of the CompositeDB combines two spatial databases. It could be extended to allow combining an arbitrary number of spatial databases, but we have not encountered sufficient uses cases to implement this feature.

Pyre User Interface

See CompositeDB component.

Examples

We create a CompositeDB with density, dilatational wave speed (Vp), and shear wave speed (Vs) from a SimpleGridDB spatial database and viscosity from a SimpleDB spatial database.

C++

Listing 15 Creating a CompositeDB in C++ that combines a SimpleGridDB with a SimpleDB.

spatialdata::spatialdb::SimpleGridDB dbElastic;
dbElastic.setFilename("elastic.spatialdb");
const size_t numElastic = 3;
const char* namesElastic[numElastic] = { "density", "Vp", "Vs" };

spatialdata::spatialdb::SimpleDB dbViscoelastic;
spatialdata::spatialdb::SimpleIOAscii ioViscoelastic;
ioViscoelastic.setFilename("viscoelastic.spatialdb");
dbViscoelastic.setIOHandler(&ioViscoelastic);
const size_t numViscoelastic = 1;
const char* namesViscoelastic[numViscoelastic] = { "viscosity" };

spatialdata::spatialdb::CompositeDB dbComposite;
dbComposite.setDBA(&dbElastic, namesElastic, numElastic);
dbComposite.setDBB(&dbViscoelastic, namesViscoelastic, numViscoelastic);

Python

Python applications should use the Pyre framework for creating the CompositeDB. We show how to do it programatically in Python for completeness.

Listing 16 Creating a CompositeDB using Python.

from spatialdata.spatialdb.SimpleGridDB import SimpleGridDB
from spatialdata.spatialdb.SimpleDB import SimpleDB
from spatialdata.spatialdb.SimpleIOAscii import SimpleIOAscii
from spatialdata.spatialdb.CompositeDB import CompositeDB

dbElastic = SimpleGridDB()
dbElastic.filename = "elastic.spatialdb"

dbViscoelastic = SimpleDB()
dbViscoelastic.iohandler = SimpleIOAscii()
dbViscoelastic.iohandler.filename = "viscoelastic.spatialdb"
dbViscoelastic.iohandler._configure()
dbViscoelastic._configure()

dbComposite = CompositeDB()
dbComposite.namesA = ["density", "Vp", "Vs"]
dbComposite.dbA = dbElastic
dbComposite.namesB = ["viscosity"]
dbComposite.dbB = dbViscoelastic
dbCompsite._configure()