Dear UCSF ChimeraX developers,

I am Chenwei Zhang, a PhD student from UBC, Canada. I am currently using ChimeraX for cryoEM density map visualization, which did a really nice job. There's one question I would like to seek answers from you. When I show a density map in ChimeraX GUI, it show automatically show a threshold level. Here's a quick example when I open emd_6272.map file: Opened emd_6272.map as #1, grid size 108,108,108, pixel 1.02, shown at level 0.0555, step 1, values float32

May I ask how does ChimeraX get this threshold? Or more generally, how does ChimeraX calculate the density values to get this final threshold value? Is there any command I could use in ChimeraX to extract this value? I tried to find answers in your documentation but failed so I am writing this email for help.

Thank you in advance and look forward to your reply.

Best,
Chenwei