this image has just popped up online apparantly snapped from an advanced screening of T4.
We all know Arnold was reportedly going to be cgi'd on to Roland Kickingers body but going by this picture if it is legit they have just decided to crop Arnold from his arrival scene in T1 and superimpose him into T4.
I found a clip of T1 on youtube which was poor quality and captured almost exactly the same frame and placed it next to this new shot.
Despite it being poor quality and the fact the new pic is a photo of a screen you can clearly see the lighting is the same across the whole body as is the structure.