Azure Digital Twins (ADT), and its underlying Digital Twins Definition Language (DTDL), are at the heart of Smart Facilities solutions built on Azure.
DTDL is the language by which developers can define the language of the entities they expect to use in their topologies. Since DTDL is a blank canvas which can model any entity, it is important to accelerate developers' time to results by providing a common domain-specific ontology to bootstrap solution building, as well as seamless integration between DTDL-based solutions from different vendors.
This is a set of open-source ontology tools which one can use to operate on any ontologies, including the Real Estate Core Ontology
You can upload an ontology into your own instance of ADT by using UploadModels. Follow the instructions on Upload to upload all of these models into your own instance. Here is an article on how to manage models, update, retrieve, update, decommission and delete models.
You can also delete models that are previously uploaded to an instance of ADT. For this you can use the DeleteModels tool. Instructions of how this can be run are found here
Once you have uploaded these models into your Azure Digital Twins instance, you can view the ontology using Azure Digital Twins Explorer.
The DTDL RealEstateCore models in this repo have already been validated. You don't have to validate them with the DTDL parser unless you change them. If you have extended the models or made changes, it's recommended to validate the models as described by this article: Validate models.
The OntologyMapper is an assembly that is used to support conversion from one DTDL ontology to another DTDL ontology. More details can be found here