[Chimera-users] Difference maps

[Elaine Meng]

Hi Kat,
I don't think there is an abs(X) function, but "vop scale" can shift all the values by a constant:
<http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/vop.html#scale>
That is, you could shift the map values to positive only.  

However, that might not be necessary... you might first try just turning off the "cap high values" option in Volume Viewer as described in this previous post:
<http://plato.cgl.ucsf.edu/pipermail/chimera-users/2008-March/002449.html>
In Volume Viewer, choose "Features... Surface and Mesh options" to show that setting in the dialog.

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 Sep 1, 2010, at 10:41 AM, Katrina Lexa wrote:

>  Hello,
> I'm wondering whether it is possible to take the absolute value of a 
> difference map created by the vop subtract command? Otherwise, so far as 
> I can tell, the negative values which should be relevant I can't see 
> because they just show up as a giant box.
> Thank you for your help,
> Kat