[Bf-docboard-svn] bf-manual: [9031] branches/blender-3.1-release/blender_docs/manual/render/cycles/object_settings/cameras.rst: Cycles: document Fisheye Lens Polynomial

[Brecht Van Lommel]

Revision: 9031
          https://developer.blender.org/rBM9031
Author:   brecht
Date:     2022-02-25 19:56:18 +0100 (Fri, 25 Feb 2022)
Log Message:
-----------
Cycles: document Fisheye Lens Polynomial

Modified Paths:
--------------
    branches/blender-3.1-release/blender_docs/manual/render/cycles/object_settings/cameras.rst

Modified: branches/blender-3.1-release/blender_docs/manual/render/cycles/object_settings/cameras.rst
===================================================================
--- branches/blender-3.1-release/blender_docs/manual/render/cycles/object_settings/cameras.rst	2022-02-25 05:03:24 UTC (rev 9030)
+++ branches/blender-3.1-release/blender_docs/manual/render/cycles/object_settings/cameras.rst	2022-02-25 18:56:18 UTC (rev 9031)
@@ -60,6 +60,20 @@
    Field of view angle, going to 360 and more to capture the whole environment.
 
 
+Fisheye Lens Polynomial
+-----------------------
+
+Match a real world camera by specifying the coordinates of a 4th degree polynomial.
+A position :math:`(x, y)` on the camera sensor in mm is mapped to a direction with
+spherical coordinates :math:`(1, \theta, \phi)` in radians as follows: 
+
+.. math::
+  & r = \sqrt{x^2 + y^2}\\
+  & \theta = k_0 + k_1 r + r^2 k_2 + r^3 k_3 + r^4 k_4\\
+  & \phi = acos(x/r)
+
+This can be used to model both fisheye and perspective cameras.
+
 Mirror Ball
 -----------