GreedyProjectionTriangulation

Describe the bug

I use GreedyProjectionTriangulation to create trainglular mesh from a point cloud. However, there are many triangles' normal direction are in opposite direction compared to the others. I have try to change input parameters but it always has the same issue.

Context

try to reconstruct surface from a scanning point cloud.

Expected behavior

All traingles' normal direction should be consistent in reconstructed mesh.

Current Behavior

Many triangles' normal direction are in opposite direction compared to the others.

What happens instead of the expected behavior?

To Reproduce

data.zip

1. load surf_moving.pcd in attached zip file.
2. The point cloud is point normal cloud.
3. use the code snippets for GreedyProjectionTriangulation
4. The result is shown as surf_moving.ply

Screenshots/Code snippets

• screenshots of the GUI issues
  
• code snippets:

		pcl::GreedyProjectionTriangulation<pcl::PointNormal> gp3;
		pcl::PolygonMesh mesh;

		gp3.setMu(2.5);
		gp3.setMaximumNearestNeighbors(100);
		gp3.setMaximumSurfaceAngle(M_PI / 4); // 45 degrees
		gp3.setMinimumAngle(M_PI / 18); // 10 degrees
		gp3.setMaximumAngle(2 * M_PI / 3); // 120 degrees
		gp3.setNormalConsistency(false);
		gp3.setInputCloud(cloud_normals);
		gp3.setSearchMethod(tree);
		gp3.reconstruct(mesh);

Your Environment (please complete the following information):

• OS: Windows 10
• Compiler: Visual Studio 2017 C++
• PCL Version 1.9

Start with the GreedyProjectionTriangulation usage shown in the issue and reproduce it with surf_moving.pcd from the attached data.zip, using the provided code and PCL 1.9 environment. Compare the generated surf_moving.ply with the input point normals and investigate why triangle directions differ; done means the reconstructed mesh has consistent triangle normal directions.