[chimerax-users] Dome projection camera mode

[Tom Goddard]

Hi Tibor,

The Chimera dome camera mode is not available in ChimeraX.  It is not the same as field of view 90 degrees. The dome mode renders a hemisphere (half of a sphere), so the field of view is 180 degrees.  You can't use 180 degree field of view with a perspective projection since it would project onto an infinitely wide plane.  If you use less than 180 degrees, e.g. 179 degrees the radial mapping of a perspective projection will be completely different than the radial fisheye mapping.  In the fisheye rendering typically used by domes, the distance of an image pixel from the image center is proportional to the view angle from the center of view.  A perspective projection is not even close to that.  So in short, you can't simulate a dome projection with current ChimeraX camera modes.

It would take some days of work to add dome camera mode to ChimeraX.  We have no funding for that and very few people will use it so I'm afraid that is not likely to be implemented.

	Tom


> On Mar 26, 2019, at 12:59 PM, Elaine Meng <meng at cgl.ucsf.edu> wrote:
> 
> Hi Tibor,
> As you have seen, ChimeraX does not have a dome camera mode as one of the choices of the “camera” command.
> <http://rbvi.ucsf.edu/chimerax/docs/user/commands/camera.html>
> 
> Unfortunately I do not know if it is possible to simulate it with available parameters, or how likely it is to be implemented — our “expert” in this area is away until mid-April.  Just thought I should let you know it may be a while before you get a more definitive response.
> 
> Just from reading the description of the dome camera mode in Chimera:
> "dome - angular fisheye of the hemisphere in front of the camera, with horizontal field of view locked to 90°”
> 
> …one low-conviction guess is that you could try setting the ChimeraX “fieldofView” parameter to 90 degrees (this is also an option of the “camera” command). However, it’s likely there are other details of the dome camera mode in Chimera that this would not adequately represent.
> Best,
> Elaine
> -----
> Elaine C. Meng, Ph.D.                       
> UCSF Chimera(X) team
> Department of Pharmaceutical Chemistry
> University of California, San Francisco
> 
> 
>> On Mar 26, 2019, at 10:27 AM, Tibor Füzik <tibor.fuzik at ceitec.muni.cz> wrote:
>> 
>> Dear ChimeraX developers,
>> I have not found the "dome" projection camera mode in ChimeraX (as it is in Chimera). Is there any equivalent projection (camera mode) or a workaround to get it? Would it be hard to implement it ChimeraX?
>> Thanks.
>> All the best,
>> 
>> Tibor
> 
> 
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