Merge pull request #14411 from ostarling:3.4_fix_for_14242

* Fix for Homogenous precision #14242:
 - moved scale computation to an inline function
 - use std::numeric_limits<float>::epsilon() instead of != 0.0

* Fix for Homogenous precision #14242:
 - fixed warnings for type conversion

* Fix for Homogenous precision #14242:
 - use float epsilon() for truncation of doubles

modules/calib3d/src/fundam.cpp

@@ -909,6 +909,14 @@ void cv::computeCorrespondEpilines( InputArray _points, int whichImage,
     }
 }
 
+static inline double scaleFor(double x){
+    return (std::fabs(x) > std::numeric_limits<float>::epsilon()) ? 1./x : 1.;
+}
+static inline float scaleFor(float x){
+    return (std::fabs(x) > std::numeric_limits<float>::epsilon()) ? 1.f/x : 1.f;
+}
+
+
 void cv::convertPointsFromHomogeneous( InputArray _src, OutputArray _dst )
 {
     CV_INSTRUMENT_REGION();
@@ -967,7 +975,7 @@ void cv::convertPointsFromHomogeneous( InputArray _src, OutputArray _dst )
             Point2f* dptr = dst.ptr<Point2f>();
             for( i = 0; i < npoints; i++ )
             {
-                float scale = sptr[i].z != 0.f ? 1.f/sptr[i].z : 1.f;
+                float scale = scaleFor(sptr[i].z);
                 dptr[i] = Point2f(sptr[i].x*scale, sptr[i].y*scale);
             }
         }
@@ -977,7 +985,7 @@ void cv::convertPointsFromHomogeneous( InputArray _src, OutputArray _dst )
             Point3f* dptr = dst.ptr<Point3f>();
             for( i = 0; i < npoints; i++ )
             {
-                float scale = sptr[i][3] != 0.f ? 1.f/sptr[i][3] : 1.f;
+                float scale = scaleFor(sptr[i][3]);
                 dptr[i] = Point3f(sptr[i][0]*scale, sptr[i][1]*scale, sptr[i][2]*scale);
             }
         }
@@ -990,7 +998,7 @@ void cv::convertPointsFromHomogeneous( InputArray _src, OutputArray _dst )
             Point2d* dptr = dst.ptr<Point2d>();
             for( i = 0; i < npoints; i++ )
             {
-                double scale = sptr[i].z != 0. ? 1./sptr[i].z : 1.;
+                double scale = scaleFor(sptr[i].z);
                 dptr[i] = Point2d(sptr[i].x*scale, sptr[i].y*scale);
             }
         }
@@ -1000,7 +1008,7 @@ void cv::convertPointsFromHomogeneous( InputArray _src, OutputArray _dst )
             Point3d* dptr = dst.ptr<Point3d>();
             for( i = 0; i < npoints; i++ )
             {
-                double scale = sptr[i][3] != 0.f ? 1./sptr[i][3] : 1.;
+                double scale = scaleFor(sptr[i][3]);
                 dptr[i] = Point3d(sptr[i][0]*scale, sptr[i][1]*scale, sptr[i][2]*scale);
             }
         }