Gigapixel Challenges: Vignetting part 2

As you saw in the previous post vignetting in the individual frames and layers can be very obvious. Since the photo was shot at different exposures, I can use the HDR merge features of the stitching tool Autopano. After making some adjustments to the configurations to prioritize reduction in vignetting and a 2nd stitch yielded this pano. The vignette artifacts are still evident on the left side of the picture, and throughout the sky, but the majority of the foreground from the center to the right side is now clean enough to pass. At this point I will resort to a pre-processing filter that makes a lens and camera specific adjustment to all the pictures prior to stitching, unfortunately this process is not multi-threaded, so it will likely run in the background for at least 24 hours before I can do another stitch.