At this moment you should notice the arrow object does not align to the Maya render even though you had the focal length value set to 35, the same value back in Maya. This is where I have yet to find out why, (hopefully someone could let me know) but for now we would have to tweak the focal length number inside BodyPaint to match it to the Maya render. To make things easier, we will set the Display on the viewport to Lines and start tweaking.

After much tweaking with focal length numbers, I came a conclusion that you need to take the focal length value from Maya and multiply it by 1.5. Which means, in this case, its 52.5 for the focal length inside BodyPaint3D. That's about it really.

What you could do with this setup is that, at times you may need to model based on the photographs and the alignment you did could then be used to have perfect texture projection onto the model. Thus saving a lot of times on texture creation at the same time achieving realistic result.

Hope you find the information useful.