ENH: use external function to compute earth-sun distance from OTB-atmo project

Code/Radiometry/otbImageToReflectanceImageFilter.h

@@ -22,6 +22,7 @@
 #ifndef __otbImageToReflectanceImageFilter_h
 #define __otbImageToReflectanceImageFilter_h
 
+#include "otbVarSol.h"
 #include "otbUnaryImageFunctorWithVectorImageFilter.h"
 #include "otbImageToLuminanceImageFilter.h"
 #include "otbLuminanceToReflectanceImageFilter.h"
@@ -315,12 +316,8 @@ protected:
         {
         if (m_Day * m_Month != 0 && m_Day < 32 && m_Month < 13)
           {
-          otb_6s_doublereal dsol = 0.;
-          otb_6s_integer    day = static_cast<otb_6s_integer>(m_Day);
-          otb_6s_integer    month = static_cast<otb_6s_integer>(m_Month);
-          //int               cr(0);
-          otb_6s_varsol_(&day, &month, &dsol);
-          coefTemp = vcl_cos(m_ZenithalSolarAngle * CONST_PI_180) * static_cast<double>(dsol);
+          double dsol = VarSol::GetVarSol(m_Day, m_Month);
+          coefTemp = vcl_cos(m_ZenithalSolarAngle * CONST_PI_180) * dsol;
           }
         else
           {

Code/Radiometry/otbLuminanceToReflectanceImageFilter.h

@@ -22,7 +22,7 @@
 #ifndef __otbLuminanceToReflectanceImageFilter_h
 #define __otbLuminanceToReflectanceImageFilter_h
 
-#include "otb_6S.h"
+#include "otbVarSol.h"
 #include "otbUnaryImageFunctorWithVectorImageFilter.h"
 #include "otbVectorImage.h"
 #include "otbMath.h"
@@ -297,12 +297,8 @@ protected:
         {
         if (m_Day * m_Month != 0 && m_Day < 32 && m_Month < 13)
           {
-          otb_6s_doublereal dsol = 0.;
-          otb_6s_integer    day = static_cast<otb_6s_integer>(m_Day);
-          otb_6s_integer    month = static_cast<otb_6s_integer>(m_Month);
-          //int               cr(0);
-          otb_6s_varsol_(&day, &month, &dsol);
-          coefTemp = vcl_cos(m_ZenithalSolarAngle * CONST_PI_180) * static_cast<double>(dsol);
+          double dsol = VarSol::GetVarSol(m_Day, m_Month);
+          coefTemp = vcl_cos(m_ZenithalSolarAngle * CONST_PI_180) * dsol;
           }
         else
           {

Code/Radiometry/otbVarSol.h

+/*=========================================================================
+
+  Program:   ORFEO Toolbox
+  Language:  C++
+  Date:      $Date$
+  Version:   $Revision$
+
+
+  Copyright (c) Centre National d'Etudes Spatiales. All rights reserved.
+  See OTBCopyright.txt for details.
+
+
+     This software is distributed WITHOUT ANY WARRANTY; without even
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+     PURPOSE.  See the above copyright notices for more information.
+
+=========================================================================*/
+#ifndef __otbVarSol_h
+#define __otbVarSol_h
+
+#include "otbMath.h"
+
+namespace otb
+{
+
+/** \class VarSol
+   * \brief VarSol operations.
+   *
+   * Call VarSol main function
+   *
+   * [1] Vermote, E., Tanré, D., Deuze, J., Herman, M., Morcette, J., 1997. 
+   * Second simulation of the satellite signal in the solar spectrum, 6S: An overview. 
+   * IEEE Transactions on Geoscience and Remote Sensing 35
+   * \ingroup Radiometry
+   *
+ */
+  class ITK_EXPORT VarSol
+  {
+  public:
+    
+    /** Call the varSol function*/
+    static double GetVarSol(const int day, const int month)
+    {
+      /* System generated locals */
+      double d__1;
+      
+      /* Builtin functions */
+      //double acos(double), cos(double);
+      
+      /* Local variables */
+      int j;
+      double pi, om;
+      
+      /* calculation of the variability of the solar constant during the year. */
+      /* day is the number of the day in the month */
+      if (month <= 2) 
+	j = (month - 1) * 31 + day;
+      else if (month > 8) 
+	j = (month - 1) * 31 - (month - 2) / 2 - 2 + day;
+      else
+	j = (month - 1) * 31 - (month - 1) / 2 - 2 + day;
+      
+      pi = acos(0.) * 2.;
+      om = (double) (j - 4) * .9856 * pi / 180.;
+      /* Computing 2nd power */
+      d__1 = 1. - cos(om) * .01673;
+      return 1. / (d__1 * d__1);
+    }
+  };
+} //end namespace otb
+#endif
+