The impression that you get when you watch the film is that the Tantive is drawn into the Star Destroyer Bay with everything at right angles...
well, it turns out the whole thing was kind of catty-wompus...
fig. 1 photomatch results
The green lines are the geometry of my models, overlaid on a still from the movie, and with the perspective of the still matched in-program.
looks fairly straight forward, right?
the Tantive is pitched down 12 degrees from horizontal, and yawed to port about 14.
fig. 2 elevation view of photomatch results
fig. 3 plan view of photomatch results
Ultimately I don't think this was supposed to be the case, but is an unintended artifact of the effects composite. The production department didn't perfectly match the appropriate angles when the photographed the ships separately, and instead made it look passable. Still, it's kind of interesting... if you're deeply obsessed that is.