1. A method for constructing a hierarchical multi-faceted classification structure comprising: classifying a plurality of visual categories into a multi-relational reference ontology that accounts for a plurality of different types of relationships, the multi-relational reference ontology including a plurality of faceted nodes of visual categories that can co-occur in an image and a plurality of regular nodes of visual categories that are mutually exclusive in the image; determining a plurality of content-based tags for one or more media artifacts, wherein each content-based tag of the plurality of content-based tags is determined based on a confidence score using the plurality of visual categories; for a set of conflicting content-based tags from the plurality of content-based tags, removing all but one conflicting content-based tag from visual categories that are mutually exclusive for each of the one or more media artifacts; storing the multi-relational reference ontology, remaining content-based tags of the plurality of content-based tags, and the one or more media artifacts with relationships as a hierarchical multi-faceted classification structure in computer readable memory storage; and retrieving at least one media artifact from the one or more media artifacts by at least one content-based tagging application using the multi-relational reference ontology and the remaining content-based tags.