[Chimera-users] soft roll off edges with Zone masks

hi Chimera users We have determined a pseudo-atomic resolution cryoEM density of a helical co-polymer (two unique chains for the repeating hetero-dimer). We would like to compute map-versus-model FSC curves for each of the unique chains. We'd like to use the Zone tool to mask out the relevant density per chain within ~3A or so of the atoms in our atomic model, but we would like the edges of this mask to be appropriately "soft" (whereas right now zone masking appears to employ a hard edge). has anyone already solved this problem? ~Adam