API Reference > imodeljs-backend > iModels > IModelTransformer > initFromExternalSourceAspects initFromExternalSourceAspects Method Initialize the source to target Element mapping from ExternalSourceAspects in the target iModel. initFromExternalSourceAspects(): void note This method is called from IModelTransformer.processChanges and IModelTransformer.processAll, so it only needs to be called directly when processing a subset of an iModel. Returns - void Defined in core/backend/src/IModelTransformer.ts Line 300 Last Updated: 12 June, 2024