When I compute normals from CloudCompare software for the PLY file I created from PCL, I am seeing the faces as shown in the picture. The normals are flipped. This issue is similar to the one mentioned in https://github.com/PointCloudLibrary/pcl/issues/1659 . I observed the same in Meshlab as well. Meshlab has the option to turn on BackFace as double to visualize it similar to PCL visualizer.
This issue occurs when the mesh is generated using pcl Concave Hull method. Not when using the Poisson Surface reconstruction. How do I get it corrected for the concave hull based surface reconstruction?
There is a MeshLab filter named ‘Re-Orient all faces coherently that will re-orient in a consistent way all the faces of the mesh.
The filter visits a mesh face to face, reorienting any unvisited face so that it is coherent to the already visited faces. If the surface is orientable it will end with a consistent orientation of all the faces. If the surface is not orientable (e.g. it is non manifold or non orientable like a moebius strip) the filter will not build a consistent orientation simply because it is not possible. The filter can end up in a consistent orientation that can be exactly the opposite of the expected one; in that case simply invert the whole mesh orientation using the filter ‘Invert Faces Orientation’