  Scene Graph Generation (SGG) offers a structured representation critical in
many computer vision applications. Traditional SGG approaches, however, are
limited by a closed-set assumption, restricting their ability to recognize only
predefined object and relation categories. To overcome this, we categorize SGG
scenarios into four distinct settings based on the node and edge: Closed-set
SGG, Open Vocabulary (object) Detection-based SGG (OvD-SGG), Open Vocabulary
Relation-based SGG (OvR-SGG), and Open Vocabulary Detection + Relation-based
SGG (OvD+R-SGG). While object-centric open vocabulary SGG has been studied
recently, the more challenging problem of relation-involved open-vocabulary SGG
remains relatively unexplored. To fill this gap, we propose a unified framework
named OvSGTR towards fully open vocabulary SGG from a holistic view. The
proposed framework is an end-toend transformer architecture, which learns a
visual-concept alignment for both nodes and edges, enabling the model to
recognize unseen categories. For the more challenging settings of
relation-involved open vocabulary SGG, the proposed approach integrates
relation-aware pre-training utilizing image-caption data and retains
visual-concept alignment through knowledge distillation. Comprehensive
experimental results on the Visual Genome benchmark demonstrate the
effectiveness and superiority of the proposed framework.
