<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi Martin,<div class=""><br class=""></div><div class=""> Fit an atomic model of the asymmetric unit then use volume zone (Volume Viewer menu entry Feature / Zone) then save the map (Volume Viewer / File / Same Map As…). See the maskZone option description in the volume save command for details</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span><a href="https://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/volume.html#output" class="">https://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/volume.html#output</a></div><div class=""><br class=""></div><div class=""> Tom<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Jul 31, 2018, at 7:00 AM, Martin Moncrieffe <<a href="mailto:mcm35@cam.ac.uk" class="">mcm35@cam.ac.uk</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Hi Tom,<br class=""><br class="">A quick question. I have a helical reconstruction (EM) and would like to extract the density for the asymmetric unit from the map. How does one do this?<br class=""><br class="">Best.<br class=""><br class="">__martin<br class=""><br class=""><br class=""></div></div></blockquote></div><br class=""></div></body></html>