Trying to create a 180 deg interactive image using PTGui getting curved horizontals

[Simon Anderson]

Have been trying to create a 180 degree interactive image using multiple images capture using a nodal head setup. I can successfully create the pano however when I try and output the image the horizontals are all distorted and curved. I can preview the image in PTGui using the detail viewer and the image looks great with perfectly strait verticals and horizontals. However when I output the image the horizontals alway become curved. Can anyone suggest what setting I should be using to avoid this. 

[John Houghton]

Simon, Probably the explanation for the unwanted  distortions you are seeing is to do with the projections used for a display of the images.  PTGui does its stitching on the surface of a sphere in order to encompass the view in all directions.  The Detail Viewer shows an extracted rectilinear view, in which all straight line features are preserved.  Your output of the entire 180 degree view is probably in equirectangular or cylindrical projection. See  Projections - PTGui Stitching Software for an explanation of the projections.  To get a straight horizon and perfectly upright vertical features, your panorama needs to be levelled, see Part 8 of the video tutorials on the PTGui web site (under the "Learn" heading).

John