Properly stitching a set of panoramic images to produce a VR movie or super-sized panorama requires, among other things, a perfectly level horizon. To obtain this, a device like this Jobu Design VR Panning Base is extremely useful. It has fine micro-adjustments and a easy to read bubble level to achieve a horizontal plane. The VR Base can be inserted between a tripod and its head so it fits seamlessly into your current camera support system.
Bubble level for precision levelling of your camera or tripod head