I recently took a series of 27 photos to form a hdr panorama of the grand tetons in the states. Unfortuanetly despite my best efforts some of the shots are not level. (perhaps the fact it was -20'c had something to do with this) I know how to use the ruler etc to fix this but wanted to ask a question. I took this series of photos sitting on the edge of a lake and you can clearly see the opposite side of the lake. So do i run the ruler along the opposite shoreline, or as the lake isn't huge will the roundness of the shoreline effect the leveling? Does that make sense?