  It was found that, in an isotropic coordinate system, the tunneling approach
brings a factor of 1/2 for the Hawking temperature of a Schwarzschild black
hole. In this paper, we address this kind of problem by studying the relation
between the Hawking temperature and the deformation of integral contour for the
scalar and Dirac particles tunneling. We find that correct Hawking temperature
can be obtained exactly as long as the integral contour deformed corresponding
to the radial coordinate transform if the transformation is a non-regular or
zero function at the event horizon.
