Hi, jms:
It looks like Oppy might have to go down a hill or dip before it gets to Vostok. There seems to be a small somewhat circular valley where Vostok is. Notice the change in lighting/reflected light off the rims of the craters in Vostok's viscinity. The rims of the craters to the left reflect more light than those at the bottom right.
There are features that have that shape in other sections of this photo, but it's bright enough that you can see the surface. That triange is either a deeper depression, darker soil (our question is why, right? :) or it is being shaded by that hill.
We'll find out.
I found some interesting MOLA images in this pdf (interesting paper reading too).
I like the aerial, oblique 3D perspective in this night time Themis infrared image of Meridiani (West is to the top left hand corner):
Space/Science » in reply to Vostok
re: Vostok