Hugin Optimiser tab
As explained on the Hugin Photos tab, hugin uses a photo alignment scheme where it adjusts image orientation and lens settings of source photos until the control points line-up. This process is called (geometric) optimisation. Normally you will use the Hugin Assistant tab where control points are automatically generated, or use the Feature matching option from the Hugin Photos tab to generate control points.
The pre-set optimisation options are useful for most situations, but sometimes it is necessary to switch to Custom parameters.
For example, when shooting hand-held panoramas, some of the position variation between shots can be resolved by using different d and e Image Center Shift parameters for each shot. Select Custom parameters, and pick the d and e parameters for optimisation on this hugin Optimiser tab.
Similarly, the translation parameters could be used to correct a wonky shot. However, they were meant for linear panoramas which expand to infinite distance at 180 degrees field of view, so you must make sure any images with non-zero translation (X, Y, or Z parameters) are in the middle of the panorama (y and p should all be around zero, and the field of view shouldn't be large enough to make them expand more than 180 degrees). This can be used to patch in the floor after you have removed the tripod that was obscuring it. You can take a shot of the floor where the tripod was at an angle (therefore you can avoid casting a shadow on the image in most cases). You can then optimise X,Y,Z on only this image. However, the floor must be flat for this to work, and this shot must be in the middle of the panorama. You can make down the middle by rotating the panorama on either of the previews.