[Chimera-users] savepos/reset

Elaine Meng meng at cgl.ucsf.edu
Tue Dec 9 09:30:40 PST 2008

Hi Matt,
I agree with most of what Tom said, except that "match" in the Model  
Panel is not the same as using "matrixcopy" - the "matrixcopy" command  
applies the current transformation of one model to another, whereas  
"match" in the Model Panel calls MatchMaker.  MatchMaker constructs a  
sequence alignment and uses the pairings in the alignment to  
superimpose the structures.

In the morphing case, it generally does not work to use "matrixcopy"  
after resetting the original models to some saved position, because  
the untransformed position of the morph corresponds to the transformed  
positions of the input models at the time the morph was created.  For  
example, if you use "reset" without arguments to untransform all  
models right after creating the morph, the morph will stay put whereas  
the other models will go back to their starting positions, no longer  
sensible relative to the morph position.  Initially I thought  
"matrixcopy" would work... then I actually tried it.  8-(

That still leaves the other approach Tom described:  reset to saved  
position, use MatchMaker (or matchmaker command) to superimpose the  
new model onto one of the old ones included in the saved position, re- 
save the position.   I can imagine one variant, which may not be any  
better:  after using matchmaker, write out the new model "relative to"  
the old model, close it, read it back in.  Then after resetting to the  
various saved positions, you could use "matrixcopy" to apply the old  
model's transform to the new model, since their untransformed  
coordinates are now in sync.

Perhaps all this babbling is incomprehensible - if so, I apologize!
Elaine C. Meng, Ph.D.                          meng at cgl.ucsf.edu
UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab
Department of Pharmaceutical Chemistry
University of California, San Francisco

On Dec 8, 2008, at 11:08 PM, Tom Goddard wrote:

> Hi Matt,
>  Yeah, the savepos/reset commands is pretty unfriendly.  I think the
> sensible fix is that "reset" should be changed to move unknown  
> models in
> some sensible way instead of just leaving them where they lie.  The
> common case is that the transformation of all remembered models is the
> same, so position any new model using that same transformation.  If  
> some
> models have different saved transformations then it might be  
> reasonable
> to look just at the models with the same current transformation as the
> new model -- if all those end up with the same transform then apply  
> that
> to the new model as well.  If there is some real ambiguity (models  
> with
> the same current transform match the new model and then move to
> different relative positions in the saved position) then obviously you
> have to specify how to incorporate the new model in that saved
> position.  I won't have time to work on this for probably a few  
> months.
> Perhaps another Chimera developer will look at it.
>  As things currently work I think the only approach is quite painful.
> You have to reset to a saved position then use the Model Panel  /  
> Match
> button to align your new model with one of the existing models, then
> reuse the "savepos" command with the original name to augment it.   
> Ugh.
> The matrixcopy command does the same think as the Match button and may
> be easier.
>    Tom
> Matthew Dougherty wrote:
>> Let's say I have 5 models and I save a number of positions (savepos).
>> Then I later create some morphs between the models.
>> When I do a reset of a position, the morph model's position does not
>> correspond with the other model positions.
>> This is partially due to the method of camera control in chimera of
>> moving the models and keeping the camera position pointing in the z
>> direction.
>> Is there a way to incorporate the morph model into the saved  
>> positions
>> that were created prior to the creation of the morph model?
>> having similar problem with models I open after the positions are  
>> saved.
>> thanks, Matt
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