Dear all, I would like to get variable value at a fixed point in physical space at every time step. Its coordinates are given as "HistoryPoints". However, my domain is moving and i need find the fixed point in the new mesh at every time step. So, I use the "UpdateGeometry()" in "Deform.cpp" to update mesh at every time step and then use "FillBoundingBoxTree()" in "MeshGraph.cpp" to update rtree so that i can find the id of element the fixed point locating in. However, the "FillBoundingBoxTree()" can not update m_boundingBoxTree according the new mesh and i always get the id of element the fixed point locating in initial mesh. Whether do i need to modify something other? Who can give some suggestions about how to get value at a fixed point in physical space at every time step when the mesh is moving? Thank you very much! Best, Song