Ruahrc -- I don't know what you used to level this image. I do know the horizon is perfect. The perspective gives great depth to the image. Well done.
Thanks. I do most of my stitching in Hugin so I align the images and adjust the horizon in the preview window carefully before I execute the final stitch. Sometimes I will also stitch small versions of the picture to check for things like exposure consistency and leveling before I do the full-size stitch with the slow algorithms. This is one of the reasons I kind of want to get one of them new i7 iMacs
Just to comment on the scene, it was the 2nd day we had gotten up at sunrise to shoot photos in this location. The first day the fog on the river was a lot better (there was more of it, covering more of the valley floor) but we could not shoot this location due to wildlife presence (rutting Bison) therefore we had to go to another location. We came back the 2nd day and although there were no wildlife the fog was not quite as pronounced. Not entirely a bad thing though as there is still enough for you to follow the course of the river as it meanders down and also to see what is on the valley floor. I have other panos of the area which I like a lot too but this one in particular the colors really came out well.
If anyone visits North Dakota, a stop at the North Unit of the Theodore Roosevelt NP is
highly recommended. When we were there they were re-doing all the roads in the park with stimulus money so perhaps next year the road will be perfect and freshly paved as well- not half gravel like we had it.
Ruahrc