[Bf-committers] DOF camera parameters.

[Jonathan Merritt]

Matt Ebb wrote:

>> These parameters truly "belong" to the camera, rather than to the 
>> scene or exporter settings.  This is because it makes sense for 
>> different cameras to have different settings, and for the settings to 
>> be animated with the camera itself.
>
>
> Interesting! Am I right to assume that these parameters are 
> Aqsis-specific? As in, they have no utility when rendering from within 
> Blender, and would only be shown when Aqsis is selected as a renderer?


Well, they *could* be hidden if Aqsis is not selected as a renderer.  
I'm not entirely opposed to that idea, if overwhelming opinion is to get 
rid of them the rest of the time.  However, these parameters should be 
useful to any renderer that implements DOF.  I'd be in favour of having 
these parameters visible all the time.

btw: The "Aqsis export" is *currently* Aqsis-specific, in that it calls 
Aqsis directly.  However, nothing that we've done so far is outside of 
the RenderMan specification, and hence all of the exported files should 
render in any RenderMan-compliant renderer.  I'm currently working 
through some issues to get Pixie working with the exporter as well.  I 
still go round calling it the "Aqsis exporter" though, because those of 
us currently working on it are Aqsis developers.

> The first thing that personally comes to mind for showing the in-focus 
> area is using 3 circles, as a kind of metaphor for the circles of 
> confusion in the DOF effect - 
> http://mke3.net:9000/blender/ui/controls/camera_circ_conf.png


That's got good potential - I like the way the CoCs relate to a relevant 
parameter in the final image.  In addition to the camera display size, 
there could be another size control to select the CoC diameter that the 
user wishes to view.  The positions of the CoCs would then move to the 
appropriate locations for the given diameter...

>> PS -
>> Q: Why do we need "FocalLen" when "Lens" apparently contains the same 
>> information?
>> A: Lens in Blender controls the angular field-of-view of the camera, 
>> whereas FocalLen is the camera focal length expressed in Blender 
>> scene units.  The alternative to this scheme would be to use the Lens 
>> setting in combination with a less-intuitive scale factor to find the 
>> focal length in scene units.  I thought it was best to separate these 
>> two so that the settings were available in the most straightforward 
>> fashion.
>
>
> Would the 'FocalLen' operate independently of Blender's 'Lens', or 
> would changing the 'FocalLen' actually change the zoom when looking 
> through the camera? If so, this seems a little confusing to me, having 
> two controls that change the same property, but with different scaling.


My idea is to have FocalLen operate entirely indepenently of Lens (it 
does in my current setup).  Hence, there isn't a need for another 
scaling factor.  The Lens parameter is then more correctly a "field of 
view", whereas FocalLen is "focal length".

Jonathan Merritt.