[Chimera-users] same volume data values over the entire volume

Blaas Dieter dieter.blaas at meduniwien.ac.at
Sun Jul 21 11:22:40 PDT 2019

Hi Elaine,
  thank you very much, but with a slice again colouring only works with 
"volume data gradient norm" see attached image. When changing to "volume 
data" I receive the message "no volume data for surface" and pushing 
"colour" does not change the appearance. Is there anything wrong with my 
mrc file?
bw Dieter

On 2019-07-21 18:15, Elaine Meng wrote:
> Hi Dieter,
> I don’t know specifically what’s happening in your case, but if you
> are coloring an isosurface of the same volume data, by definition all
> the values would be essentially the same.  Coloring by the volume data
> value would normally be used on a slice of that isosurface, e.g. as
> shown here:
> <http://www.rbvi.ucsf.edu/chimera/data/tutorials/volumetour/volumetour.html#colorcap>
> I hope this helps,
> Elaine
> -----
> Elaine C. Meng, Ph.D.
> UCSF Chimera(X) team
> Department of Pharmaceutical Chemistry
> University of California, San Francisco
>> On Jul 21, 2019, at 5:36 AM, Dieter Blaas 
>> <dieter.blaas at meduniwien.ac.at> wrote:
>> Hi,
>>     Trying to color a volume according to "volume data" I get the same 
>> numerical values for all colors and a speckled appearance. When using 
>> "volume data gradient norm" I get the expected colors, i.e. strong 
>> local changes of the volume data are red and spots where there is 
>> essentially no change are in blue. How is this possible? If I 
>> understand correctly, "volume data gradient norm" colors according to 
>> the first derivative of "volume data" or is this wrong?  Do I need 
>> something like a normalization?
>> Thanks a lot for explanations,
>> best, Dieter

Dr. Dieter Blaas
Max F. Perutz Laboratories,
Inst. Med. Biochem.,
Med. Univ. Vienna
Dr. Bohr Gasse 9/3
A-1030 Vienna, Austria
Tel. 0043 1 4277 61630
Fax  0043 1 4277 9616
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