mayavi2: pythonic access from data_set_clipper filter

Question

I've applied a rectangular prism filter to my point cloud data, and would like to access the data contained within the prism. This seems like it should be simple, and probably is.

I have created the clipper and adjusted it

p3d = view_ply_file('data/my_file.ply')  #returns mayavi.mlab.points3d() instance
clip = mlab.pipeline.data_set_clipper(p3d)

#... manual interactive GUI adjustment

clip.outputs[0].points #? is empty.

How do I retrieve the contained points? I'm currently looking into the underlying vtk API, but perhaps someone with VTK or mayavi experience has some insight.

Answer 1

After finding the VTK docs much more useful than the mayavi docs on the matter, I came up with a way to extract the corners from the clipping prism. A point-in-polygon test is still needed. Update: figured the rest out. There are likely many ways to optimize - this is the naivest solution. Hopefully someone will benefit from this.

def get_clip_corners(clip):
    hack_mesh = tvtk.api.tvtk.PolyData()
    clip.widget.widget._vtk_obj.GetPolyData(hack_mesh._vtk_obj)
    corners = hack_mesh.points.to_array()[:8, :]
    return corners, hack_mesh

def get_inside_mask(sep, data):
    is_in = numpy.zeros((data.shape[0],), dtype = numpy.bool)
    for (di, d) in enumerate(data):
        di_in = sep.is_inside_object(d[0], d[1], d[2])
        is_in[di] = di_in
    return is_in

def extract_points_inside_clip(clip, data):
    corners, mesh = get_clip_corners(clip)

    sep = tvtk.api.tvtk.SelectEnclosedPoints()
    sep.initialize(mesh)

    is_in = get_inside_mask(sep, data)
    data_in_box = data[is_in, :]
    return data_in_box