Map boundary fields from one mesh to another
 

Hi everyone,
I am working on developing a solver and now struggling with how to copy boundary field values from one mesh to another (possible with different shape and mesh density). Here are some knowledges related from my view and can anyone point out the smart way to do so.
1.use the class meshTomesh and functoin mapSrcToTgt. This way I can copy the whole fields from one to another. However, I just want to map the value at boundary mesh, which I haven't found the exact express of functions to do.
2.use function from mappedField.H, from my understanding, this is a boundary condition setting file. There may be some functions helping with my work. Any hints?
3.I also found function fvPatchMapper/fvBoundaryMeshMapper/..., I am not sure this can also work?
Anyone who can help? Thanks.