A novel framework for 3D freehand tracking is put forward in this paper. Firstly, we model and investigate this problem under our virtual assembly system (VAS), so as to decrease the arbitrariness and complexity of this issue. Secondly, we put emphasis on building cognitive and behavioral model (BM) for users in VAS. Thirdly, we research on the way to track 3D freehand based on BM. Our experimental results show that the proposed approach raises the quality of each sampled particle or avoid sampling 'poor' particles which appear with low probability in each frame, and it tracks 3D freehand in real-time with high accuracy. The number of the drawn particles is reduced up to 5 and the tracking speed increase up to 81 ms per frame. An alert was just sent to the Computer Society Digital Library (CSDL) department and we will restore this missing publication as soon as possible. Source. Looking for vector maps of Germany (Deutschland Vektorkarten) for Adobe Illustrator?."