[Chimera-users] Opaque volume planes

Tom Goddard goddard at cgl.ucsf.edu
Tue Feb 12 17:41:06 PST 2008

Hi Jeff,

  The trouble obtaining opaque volume planes is not related to volume 
plane display being built into the volume dialog.  It is related to a 
change I made in how transparency is handled in solid mode back in Aug 2007.

  Today I changed transparency in "solid" style volume rendering so it 
is easier to obtain completely opaque data planes.  In tonight's builds 
(if they succeed, may not since we are switching to Python 2.5 today) 
you can obtain completely opaque volume planes by using the "Brightness 
and Transparency" panel of the volume dialog to set transparency to 0.  
This transparency value represents the fraction (0-1) of the depth of 
the volume required to produce opacity to the degree indicated by the 
height of the yellow curve on the histogram.  In other words it 
modulates the overall transparency.  But until today it was arbitrarily 
deciding not to modulate the transparency if this depth was less than 
one grid spacing.  This meaning of the transparency factor was 
introduced in August 2007, and prior to that the transparency factor 
just scaled the opacity given by the yellow curve.


Jeff wrote:
> hi Tom,
> in the older (plug-in) volume planes tool, I was able to generate 
> images that were opaque planes. I don't seem to be able to do this 
> anymore, even with transparency = 0. is there a way for me to do this 
> in the current Chimera?

More information about the Chimera-users mailing list