Hi Zheng Liu, Your command has “step 1” twice, but that should be OK… I believe it indicates using the full data in the calculation of the morph map. http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/vop.html#morph I'm not sure why the display uses step 8 of that map, or if it’s a bug, but here is one idea: There is a volume option that by default, if a map is larger than a certain size, the display step size is automatically increased. You could try turning off that behavior, for example with command: volume #4 limitVoxelCount false Details on that option http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/midas/volume.html#sampling I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco

On Jan 4, 2018, at 7:09 AM, Zheng Liu wrote:

I want create a morph volume between 2 maps (#0, and #1), as a command I wrote: vop morph #0,1 step 1 playStep 0.04 frames 200 step 1

However, the new model #4 morph was display in step "8", not step "1" in the volume view window. How to set the step size in the vop morph command? Thanks!