'Factors to rescale the triangulation into a unit square.
Returns *k*, tuple of 2 scale factors.
Returns
k : tuple of 2 floats (kx, ky)
Tuple of floats that would rescale the triangulation :
``[triangulation.x * kx, triangulation.y * ky]``
fits exactly inside a unit square.'

@property
def scale_factors(self):

    compressed_triangles = self._triangulation.get_masked_triangles()
    node_used = (np.bincount(np.ravel(compressed_triangles), minlength=self._triangulation.x.size) != 0)
    return ((1 / np.ptp(self._triangulation.x[node_used])), (1 / np.ptp(self._triangulation.y[node_used])))
