computeTriangleMeshArea() : calculate the area of a triangle mesh

PointCloudLibrary · Sep 9, 2023 · 12d02bb · 12d02bb
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diff --git a/surface/include/pcl/surface/gp3.h b/surface/include/pcl/surface/gp3.h
@@ -513,6 +513,51 @@ namespace pcl
       }
   };
 
+   /** \brief Calculate the area of a triangle mesh
+   * \param[in] cloud the point cloud to which the mesh is applied
+   * \param[in] triangleMesh a triangle mesh
+   * \return the mesh area
+   * \note example of use:
+   * pcl::GreedyProjectionTriangulation<PointN> gp;
+   * ...
+   * gp.setInputCloud(cloud_with_normals)
+   * ...
+   * pcl::PolygonMesh pm;
+   * gp3.reconstruct(pm);
+   * calculatePolygonArea(cloud_with_normals, pm.vertices);
+   * gp.reconstruct(pm);
+   * float functArea=computeTriangleMeshArea(cloud_with_normals, pm.polygons);
+   * \ingroup
+   * common
+   */
+  template <typename PointT>
+  inline float
+  computeTriangleMeshArea(const shared_ptr<pcl::PointCloud<PointT>>& cloud,
+                          std::vector<pcl::Vertices>& triangleMesh);
+
+   /** \brief Calculate the area of a triangle mesh
+   * \param[in] cloud the point cloud to which the mesh is applied
+   * \param[in] indices of the point cloud
+   * \param[in] triangleMesh a triangle mesh
+   * \return the mesh area
+   * \note example of use:
+   * pcl::GreedyProjectionTriangulation<PointN> gp;
+   * ...
+   * gp.setInputCloud(cloud_with_normals)
+   * ...
+   * pcl::PolygonMesh pm;
+   * gp.reconstruct(pm);
+   * float functArea=computeTriangleMeshArea(cloud_with_normals, pm.polygons);
+   * \ingroup
+   * common
+   */
+
+  template <typename PointT>
+  inline float
+  computeTriangleMeshArea(const shared_ptr<pcl::PointCloud<PointT>>& cloud,
+                          const shared_ptr<Indices>& indices,
+                          std::vector<pcl::Vertices>& triangleMesh);
+
 } // namespace pcl
 
 #ifdef PCL_NO_PRECOMPILE

diff --git a/surface/include/pcl/surface/impl/gp3.hpp b/surface/include/pcl/surface/impl/gp3.hpp
@@ -1667,6 +1667,59 @@ pcl::GreedyProjectionTriangulation<PointInT>::getTriangleList (const pcl::Polygo
 #define PCL_INSTANTIATE_GreedyProjectionTriangulation(T)                \
   template class PCL_EXPORTS pcl::GreedyProjectionTriangulation<T>;
 
+template <typename PointT>
+inline float
+pcl::computeTriangleMeshArea(const shared_ptr<pcl::PointCloud<PointT>>& cloud,
+                             std::vector<pcl::Vertices>& triangleMesh)
+{
+  const pcl::PointCloud<PointT>::ConstPtr input_ = cloud;
+  double area = 0;
+  for (auto& triangle_ : triangleMesh) {
+    if (triangle_.vertices.size() == 3) {
+      const Eigen::Matrix<double, 3, 1> P(
+          (*input_)[triangle_.vertices[0]].x - (*input_)[triangle_.vertices[2]].x,
+          (*input_)[triangle_.vertices[0]].y - (*input_)[triangle_.vertices[2]].y,
+          (*input_)[triangle_.vertices[0]].z - (*input_)[triangle_.vertices[2]].z);
+      const Eigen::Matrix<double, 3, 1> Q(
+          (*input_)[triangle_.vertices[1]].x - (*input_)[triangle_.vertices[2]].x,
+          (*input_)[triangle_.vertices[1]].y - (*input_)[triangle_.vertices[2]].y,
+          (*input_)[triangle_.vertices[1]].z - (*input_)[triangle_.vertices[2]].z);
+      area += 0.5 * P.cross(Q).norm();
+    }
+  }
+  return area;
+}
+
+template <typename PointT>
+inline float
+pcl::computeTriangleMeshArea(const shared_ptr<pcl::PointCloud<PointT>>& cloud,
+                             const shared_ptr<Indices>& indices,
+                             std::vector<pcl::Vertices>& triangleMesh)
+{
+  const pcl::PointCloud<PointT>::ConstPtr input_ = cloud;
+  double area = 0;
+  for (auto& triangle_ : triangleMesh) {
+    if (triangle_.vertices.size() == 3) {
+      const Eigen::Matrix<double, 3, 1> P(
+          (*input_)[(*indices_)[triangle_.vertices[0]]].x -
+              (*input_)[(*indices_)[triangle_.vertices[2]]].x,
+          (*input_)[(*indices_)[triangle_.vertices[0]]].y -
+              (*input_)[(*indices_)[triangle_.vertices[2]]].y,
+          (*input_)[(*indices_)[triangle_.vertices[0]]].z -
+              (*input_)[(*indices_)[triangle_.vertices[2]]].z);
+      const Eigen::Matrix<double, 3, 1> Q(
+          (*input_)[(*indices_)[triangle_.vertices[1]]].x -
+              (*input_)[(*indices_)[triangle_.vertices[2]]].x,
+          (*input_)[(*indices_)[triangle_.vertices[1]]].y -
+              (*input_)[(*indices_)[triangle_.vertices[2]]].y,
+          (*input_)[(*indices_)[triangle_.vertices[1]]].z -
+              (*input_)[(*indices_)[triangle_.vertices[2]]].z);
+      area += 0.5 * P.cross(Q).norm();
+    }
+  }
+  return area;
+}
+
 #endif    // PCL_SURFACE_IMPL_GP3_H_