[Chimera-users] Map Oddities

[Albion Baucom]

Thanks Tom. That is a very thorough responce, and very enlightening.

I guess my last question is then how to figure out how Chimera  
computed the new origin. It appears after closer inspection that my  
file is an older MRC file in fact.

According to the Volume Viewer the origin in Chimera of this map is  
(-224,-224,-224). Could you briefly explain how that was computed  
from the data below? I can't seem to figure out from the map header  
info how that origin would have been computed (other than header info  
I can't see, and then maybe you can suggest how I could dump ALL the  
header data). Other than reading it directly from the file it appears  
that mrc_format.py may also apply a "scale_and_skew" operation (from  
griddata.py) to the origin data. Im not sure what that is doing, but  
it might explain how the origin Chimera computed was derived from the  
data below ...

Thanks again.

Albion

Grid        =         96        96        96
Origin      =        -48       -48       -48
Extent      =         96        96        96
Cell        =    213.423   213.423   213.423    90.000    90.000
90.000
UVW         =          1         2         3
Spcgrp      =          1      Nr of points =     884736
Density min = -6.915E-01      Max          =  2.397E+00
Average     =  7.247E-11      Sigma        =  2.290E-01
Variance    =  5.243E-02
Mappage Prod=  8.257E+01      Plus         =         57
Dyn. range  = -6.903E-01      To           =  2.398E+00
Cell vol.   =  9.721E+06      Voxel vol.   =  1.099E+01
Grid vol.   =  9.721E+06      %Cell vol.   =     100.00
Origin frac =   -0.50000  -0.50000  -0.50000
Origin Cart =   -106.712  -106.712  -106.712
Top frac    =    0.48958   0.48958   0.48958
Top Cart    =    104.488   104.488   104.488
Spacing     =      2.223     2.223     2.223
Top         =         47        47        47
Changes     = F