Hi,

I notice that Chimera has slightly different in calculation of transform when I tried to rotate my EM density (200x200x200 mrc file) using Chimera. The origin of the density reported by Volume Viewer is 0,0,0

First, I print out the homologous transform matrix using:

>>> om = chimera.openModels
>>> mlist = om.list()
>>> m = mlist[0]
>>> print m.openState.xform

The transformation is:

1 0 0 0

0 1 0 0

0 0 1 0

If I rotate the model using command:

roll z -30 1

Then print out the transform matrix again:

0.866025 0.5 0 -36.8852

-0.5 0.866025 0 61.2937

0 0  0 1

That would be weird because I didn’t do any translation.

So what is really happening in Chimera when I rotate the model?

Best,

Huy