Added a helpful comment on the scale parameter of the spherical

warper.

modules/stitching/include/opencv2/stitching/detail/warpers.hpp

@@ -214,7 +214,8 @@ struct CV_EXPORTS SphericalProjector : ProjectorBase
 
 /** @brief Warper that maps an image onto the unit sphere located at the origin.
 
- Projects image onto unit sphere with origin at (0, 0, 0).
+ Projects image onto unit sphere with origin at (0, 0, 0) and radius scale, measured in pixels. 
+ A 360° panorama would therefore have a resulting width of 2 * scale * PI pixels. 
  Poles are located at (0, -1, 0) and (0, 1, 0) points.
 */
 class CV_EXPORTS SphericalWarper : public RotationWarperBase<SphericalProjector>
@@ -222,7 +223,8 @@ class CV_EXPORTS SphericalWarper : public RotationWarperBase<SphericalProjector>
 public:
     /** @brief Construct an instance of the spherical warper class.
 
-    @param scale Projected image scale multiplier
+    @param scale Radius of the projected sphere, in pixels. An image spanning the
+                 whole sphere will have a width of 2 * scale * PI pixels.  
      */
     SphericalWarper(float scale) { projector_.scale = scale; }