[Bf-committers] DOF camera parameters.

[Jonathan Merritt]

Hi Everyone,

I considered posting this to the functionality board, but since it's 
code I've already written, I thought I'd post it to bf-committers... :-)

As part of the Aqsis RenderMan exporter that I've been hard at work on 
over the last two weeks, I've added some new parameters to the Blender 
camera:
    1. Focal length ("internal" camera parameter).
    2. Focal distance (distance to point of perfect focus).
    3. f-stop (traditional photographic measure of the aperture size).
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.

In the Aqsis CVS version of Tuhopuu, these camera parameters are 
completely finished, hooked up to IPOs, etc.  Here's a screenshot 
showing them in action:
    http://www.warpax.com/temp/screenshot-new-camera.png

Given that it's all set up for people to play with, I have a few 
questions.  These are probably best answered by those who are the true 
"custodians" of Blender (probably most of whom are active on this list):
    1. Are there any changes I should make?
    2. I'd like to display focal distance (the distance to the point of 
perfect focus) in the scene.  Currently, I do this with a simple cross 
along a line from the camera, which is displayed when "ShowLimits" is 
selected.  Should this display be improved?  Should it perhaps include 
some indication of the depth of field: ie, some kind of "in focus 
range", over which the focal blur is always within some arbitrary 
value?  Any ideas (or mockups) for how this should look?

Thanks, :-)

Jonathan Merritt.

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.