How do I level/straighten a panorama using horizontal / vertical line control points?
Besides straightening a panorama manually in the Panorama Editor, it’s also possible to level a panorama using ‘horizontal line’ and ‘vertical line’ control points. Such control points indicate points that should end up on a horizontal or a vertical line in the panorama. PTGui is able to modify the orientation of the panorama in such a way that the horizontal / vertical line control points are aligned on a horizontal or vertical line, respectively, in the panorama. Vertical line control points can be placed on any vertical feature in the panorama, such as the side of a building. Horizontal line control points should only be placed on the horizon itself: in a spherical panorama, all horizontal lines are curved, except for the horizon itself. For most panoramas (in particular cityscapes) it’s easiest to use only vertical line control points. One exception would be a panorama of a sea shore: here you could place horizontal line control points on the horizon. To add horizontal / vertical l
