[Bf-docboard-svn] bf-manual: [9238] branches/blender-3.2-release/blender_docs/manual/render/cycles/object_settings/cameras.rst: Cycles: update fisheye lens description

[Brecht Van Lommel]

Revision: 9238
          https://developer.blender.org/rBM9238
Author:   brecht
Date:     2022-05-03 15:58:08 +0200 (Tue, 03 May 2022)
Log Message:
-----------
Cycles: update fisheye lens description

Add clarification for Fisheye Lens Polynomial section based on the
3.1 release notes. Also corrected a type in the Mirror Ball section.

Contributed by Jacob Baum.

Modified Paths:
--------------
    branches/blender-3.2-release/blender_docs/manual/render/cycles/object_settings/cameras.rst

Modified: branches/blender-3.2-release/blender_docs/manual/render/cycles/object_settings/cameras.rst
===================================================================
--- branches/blender-3.2-release/blender_docs/manual/render/cycles/object_settings/cameras.rst	2022-05-02 08:24:16 UTC (rev 9237)
+++ branches/blender-3.2-release/blender_docs/manual/render/cycles/object_settings/cameras.rst	2022-05-03 13:58:08 UTC (rev 9238)
@@ -64,18 +64,23 @@
 -----------------------
 
 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:
 
+The projection works as follows.
+Pixels in the image are mapped to positions :math:`(x, y)` on the camera sensor in mm.
+A position on the sensor 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 + k_2 r^2 + k_3 r^3 + k_4 r^4\\
   & \phi = acos(x/r)
 
+Incoming light from this direction is then projected onto the corresponding pixel.
+
 This can be used to model both fisheye and perspective cameras.
 
 Mirror Ball
 -----------
 
-Render is if taking a photo of a reflective mirror ball.
+Render as if taking a photo of a reflective mirror ball.
 This can be useful in rare cases to compare with a similar photo taken to capture an environment.