YPR- Adjust Horizontal and Vertical Level of the Panorama
Sometimes a problem will occur after you stitch a panorama, the horizon is curved like this:

This happens if the camera is not leveled well, pointing upwards or downwards when source images are shot.
Since panorama is a projection of a sphere (the world around the camera) onto a flat surface, tilting some source images results in the curve in final stitched panorama.
The 'YPR' function in Panoweavre 9.2 Beta can straighten the curved panorama. To achieve this:
Step 1. Click button to enter YPR Mode, in this mode the panorama is divided into many dragable parts;
Step 2.Use the left mouse button to drag the curved part to make the horizon of the panorama match the horizontal line in the Panoweaver editing window.
Step 3: Click button again to save your change.