I would like to know if it is possible to import models from IBM Rational Data Architect and Oracle Data Modeler into Power Designer?
I am working now integrating RTC/RRC and PowerDesigner. And yes, its possible. But has to be with scripts via PD accessing IBM RTC REST APIs. You have to have the ability to read RDF xmls and create equivalents objects in the PD side.
Do these tools store metadata as RDF?
PoerDesigner can't import directly from those tools, but there are metadata 'bridges' available from metaintegration.net and Reischmann.com.
Also bear in mind that the DDL generated from a physcial model can be a "lowest common denominator" method of moving the model to PowerDesigner.