A Study of the Frameworks for Digital Humans: Analyzing Facial Tracking evolution and New Research Directions with AI Topics: 3D Interaction Techniques and Metaphores; Agents for Human-Human Interaction; Input and Output Modalities; User Performance Evaluation; Virtual, Augmented and Mixed Reality In Proceedings of the 17th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications - Volume 2: VISIGRAPP, 154-162, 2022