[REF] Use DiscretisedDensity's index <-> physical space conversions i…

…n ProjMatrixByBinUsingRayTracing

src/buildblock/ProjDataInfo.cxx

@@ -652,5 +652,22 @@ operator>=(const ProjDataInfo& proj_data_info) const
   return (proj_data_info == *smaller_proj_data_info_sptr);
 }
 
+CartesianCoordinate3D<float>
+ProjDataInfo::
+get_bed_position() const
+{
+  return CartesianCoordinate3D<float>
+    (bed_position_horizontal, bed_position_vertical, 0);
+}
+
+CartesianCoordinate3D<float>
+ProjDataInfo::
+get_centre_of_gantry_vector_in_relative_coordinates() const
+{
+  double middle_of_first_ring_to_middle_of_last
+    = (scanner_ptr->get_num_rings() - 1) * scanner_ptr->get_ring_spacing();
+  return CartesianCoordinate3D<float>(middle_of_first_ring_to_middle_of_last / 2.F, 0, 0);
+}
+
 END_NAMESPACE_STIR
 

src/include/stir/DiscretisedDensity.h

@@ -41,6 +41,7 @@
 #include "stir/CartesianCoordinate3D.h"
 #include "stir/Array.h"
 #include "stir/IO/ExamData.h"
+#include "stir/ProjDataInfo.h"
 #include "stir/shared_ptr.h"
 #include <string>
 
@@ -253,6 +254,16 @@ template<int num_dimensions, typename elemT>
   inline BasicCoordinate<num_dimensions,int>
   get_indices_closest_to_LPS_coordinates(const CartesianCoordinate3D<float>& coords) const;
 
+  inline CartesianCoordinate3D<float>
+  get_relative_coordinates_for_gantry_coordinates
+  (const CartesianCoordinate3D<float>& coords,
+   const shared_ptr<ProjDataInfo> proj_data_info_sptr) const;
+
+  inline BasicCoordinate<num_dimensions, float>
+  get_index_coordinates_for_gantry_coordinates
+  (const CartesianCoordinate3D<float>& coords,
+   const shared_ptr<ProjDataInfo> proj_data_info_sptr) const;
+
   //@}
 
   //! Allocate a new DiscretisedDensity object with same characteristics as the current one.

src/include/stir/DiscretisedDensity.inl

@@ -304,4 +304,29 @@ get_indices_closest_to_LPS_coordinates(const CartesianCoordinate3D<float>& coord
   return round(this->get_index_coordinates_for_LPS_coordinates(coords));
 }
 
+template<int num_dimensions, typename elemT>
+CartesianCoordinate3D<float>
+DiscretisedDensity<num_dimensions, elemT>::
+get_relative_coordinates_for_gantry_coordinates
+(const CartesianCoordinate3D<float>& coords,
+ const shared_ptr<ProjDataInfo> proj_data_info_ptr) const
+{
+  // gantry coordinates are like relative coordinates, but the (0, 0, 0)
+  // point is at the center of the gantry
+  return coords
+      + proj_data_info_ptr->get_centre_of_gantry_vector_in_relative_coordinates();
+}
+
+template<int num_dimensions, typename elemT>
+BasicCoordinate<num_dimensions,float>
+DiscretisedDensity<num_dimensions, elemT>::
+get_index_coordinates_for_gantry_coordinates
+(const CartesianCoordinate3D<float>& coords,
+ const shared_ptr<ProjDataInfo> proj_data_info_ptr) const
+{
+  return this->get_index_coordinates_for_relative_coordinates
+    (this->get_relative_coordinates_for_gantry_coordinates
+     (coords, proj_data_info_ptr));
+}
+
 END_NAMESPACE_STIR

src/include/stir/ProjDataInfo.h

@@ -33,6 +33,7 @@
 
 #include "stir/VectorWithOffset.h"
 #include "stir/Scanner.h"
+#include "stir/CartesianCoordinate3D.h"
 #include "stir/shared_ptr.h"
 #include "stir/unique_ptr.h"
 #include <string>
@@ -364,7 +365,14 @@ class ProjDataInfo
 
   //! Get vertical bed position
   float get_bed_position_vertical() const { return bed_position_vertical; }
-
+
+  //! Vector represention bed position in 3D
+  CartesianCoordinate3D<float> get_bed_position() const;
+
+  //! Vector from image frame of reference (centre of first ring) to gantry centre
+  CartesianCoordinate3D<float>
+  get_centre_of_gantry_vector_in_relative_coordinates() const;
+
 protected:
   virtual bool blindly_equals(const root_type * const) const = 0;
 

src/include/stir/recon_buildblock/ProjMatrixByBinUsingRayTracing.h

@@ -199,7 +199,8 @@ public :
   CartesianCoordinate3D<int> min_index;
   CartesianCoordinate3D<int> max_index;
 
-  shared_ptr<ProjDataInfo> proj_data_info_ptr;
+  shared_ptr<ProjDataInfo> proj_data_info_sptr;
+  shared_ptr< DiscretisedDensity<3,float> > density_info_sptr;
 
 
   virtual void