The aim of this work is to study the development of virtual and augmented reality environment for the support of human-based processes in manufacturing. Virtual and augmented reality technologies can significantly reduce the development time and cost of products and processes in manufacturing. However there is currently a big gap between the conventional CAD-based processes and the advanced prototyping and validation methods offered with the use of VR and AR technology. There is a need for the virtual environments to be enriched with intelligence through the incorporation of knowledge. This will allow for complex tasks to be carried out, thus reducing the need for an ad hoc development, while the reusability of such an environment will be increased. On the one hand, augmented reality environments based on semantic knowledge and new user interaction methods can provide the means for putting the human back in the process loop at manufacturing level. On the other hand, virtual reality environments coupled with semantic knowledge can provide methods and tools that integrate 3D geometries with information/knowledge so that engineers can effectively evaluate and manipulate virtual prototypes in an immersive and interactive environment. Within the current dissertation, a generic VR and AR approach is developed based on human task analysis and knowledge mapping methods that are implemented in a Virtual and Augmented Reality Framework. The VR/AR framework is developed to be used with the two-step method approach using advanced interaction techniques. The developed method and framework are validated through a series of real life manufacturing test cases derived from both the automotive and aerospace industrial practices. Finally, an evaluation of the proposed methods and framework is carried out, based on one of the industrial test cases using quantitative metrics, giving insight on to the improvement of the engineering workflow using the proposed work compared with the conventional physical workflow.