I added two Chimera commands "newmap" and "addmaps" that allow extracting a rectangular piece of a density map with axes that are rotated relative to the original map. http://www.cgl.ucsf.edu/chimera/experimental/resample_map/resamplemap.html This is useful for extracting substructures from electron microscope tomograms. It is not part of current Chimera distributions but can be obtained as a separate plug-in from the experimental features web page: http://www.cgl.ucsf.edu/chimera/experimental/experimental.html It is called "Resample Map Commands" on that web page because data values from the original map are interpolated (i.e. resampled) on the new rotated grid. Tom