[Chimera-users] reset/stereo

Tom Goddard goddard at sonic.net
Mon Nov 29 16:32:42 PST 2010

Hi Matt,

   We discussed control of stereo parameters (eye separation, focal 
plane depth, ...) at today's Chimera meeting.  Here is what we covered.

   1) Chimera savepos and reset commands don't currently save and 
interpolate stereo camera parameters, although it is pretty easy to do 
and may be put into Chimera 1.6, but not into Chimera 1.5 which will be 
out in a week.

   2) We talked about adding sliders to the Viewing Controls (Side View) 
dialog Camera pane.  Currently you can type in numbers for eye 
separation, screen distance, ....

   3) It was pointed out that you can already control stereo parameters 
using mouse drags in the Chimera "top view" window.  Middle or right 
vertical mouse drags on the "eye" control eye separation, with 
horizontal drags controlling angular field of view, and left mouse 
button drag on the dotted focal plane line controls it's position 
(whether models appear in front of or behind physical display).


   4) We know you are interested in having a dial box or other USB 
device control stereo parameters in Chimera.  Can you suggest how 
Chimera would get events from such a device?  Would we have to include a 
specific library in Chimera?  Would it be Mac specific?  Would it use 
AppleScript?  Would the window system simply generate events that come 
to Chimera just like mouse or key click events?

   5) We discussed a need to save different named sets of stereo 
parameters, for example, for a flat panel LCD versus a large projection 

   6) With an enhanced savepos/reset you could smoothly transition 
stereo parameters in a Chimera demo, but how would you record a stereo 
animation for playback on YouTube, or on consumer 3d devices.  Know how 
to do that might motivate us to enhance the commands since distributed 
animations might be a more common use of 3d than live Chimera 


> thanks.  Yes, seeing the strength of the stereo effect dynamically changing will essential to getting the optimal parameters through test animations.
> I just got through doing some stereo animations for someone in Japan, to be played back on a large projector; so I did not get to see the final product on the big screen.  I was being directed as to stereo parameter values, which ended up being non-obvious such as extremely large eye separation (24cm)  which means it might be good to rename that parameter to encourage people to test the waters and explore the envelope.
> Another thing that would be good is a dial box that could adjust these parameters on the fly, or some kind of dedicated USB/HID like a wacom tablet pen pressure/angle.
> ________________________________________
> From: Tom Goddard
> Sent: Wednesday, November 24, 2010 3:39 PM
> To: Dougherty, Matthew T
> Cc: chimera-users at cgl.ucsf.edu BB
> Subject: Re: [Chimera-users] reset/stereo
> Hi Matt,
>     Adding the stereo parameters (eye separation, screen distance, screen
> width) to the savepos command and having the reset command linearly
> interpolate it and also the fly command using cubic interpolation would
> be quite easy.  It would be neat to see the strength of the stereo
> effect dynamically changing.
>     Darren Weber who works on Chimera animation capabilities can look
> into this.
>       Tom
>> Hi Elaine,
>> Getting these parameters in is critical to stereo animation production.
>> Without it, it becomes cumbersome for simple animations.  One set of stereo parameters that has to be typed in every time.  One stereo camera parameter set fits all camera movements of an image sequence.
>> And impossible for anything complex, such as camera transitions.
>> So in the interim it looks like one would need to generate python commands to set non-interpolated parameters and mix that with chimera script commands.  So all transitions would need to be cuts.
>> matt
>> ________________________________________
>> From: Elaine Meng
>> Sent: Wednesday, November 24, 2010 2:45 PM
>> To: Dougherty, Matthew T
>> Cc: chimera-users at cgl.ucsf.edu BB
>> Subject: Re: [Chimera-users] reset/stereo
>> Hi Matt,
>> My understanding is that a "position" (what is saved with savepos and restored with reset) includes only the following, and not any stereo parameters:
>>    *   the transformations of models (their rotations and translations relative to input coordinates)
>>    *   the overall scale
>>    *   clipping plane<http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/clipping.html>   status, locations, and orientations
>>    *   the center of rotation method<http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/sideview.html#rotation>
>> Thus the question of how stereo parameters would be interpolated is moot, since they are not even saved. This  understanding is based on explanations from the other staff and my own experiments, but perhaps the programming members of the team will have more detailed insights. Also, it may be possible to better integrate stereo parameters with position- or keyframe-saving in the future, so it is good that you are bringing up these issues.
>> Best,
>> 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 Nov 24, 2010, at 12:29 PM, Dougherty, Matthew T wrote:
>> I had a couple questions about using the reset command.
>> Let's say I have two keyframes (e.g.,  kf0,kf1) such that the stereo parameters are different between the two.
>> 1) If I do a "savepos kf0" are the stereo parameters saved as part of the keyframe?
>> 2) If I start at kf0 and do a "reset kf1 100", should the stereo parameters be interpolated across the 100 frames?
>> thanks, Matt
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