Manually create horizon line
Not all photographs have the obvious horizon line that you use in your tutorials. However, as the photographer sometimes you know where it is. It would be great if you could manually insert a horizon line where you know that it is and have it use that. i.e. just draw a horizon line on the photograph that you have used.
Great suggestion! You do still have the manual camera controls in the upper-right corner of the viewport, but drawing a horizon does seem like it would help speed that up. :)
If trying to align the perspective to an background picture (the auto align function is great but works not always good) it would be helpful one can trace pathes like an own perspective grid around a plane in the picture. For example a livingroom with a table is the background picture. Now you can trace a path/or lines around the table corners, hit a button and the Objects are then aligned to this perspective grid / perspective..
Sorry my english is bad. i hope you understand what i mean..
Being able to draw a perspective grid for the camera to adjust itself to would be great.
Ian Watts commented
So for example, I have a clear horizon line in a picture, but partially obscured by trees, so I know where I want it, but Felix cannot find it because of the trees. If I could draw it in, then the auto functions in felix would speed things up.