Planet London

Been trying this technique on a few subjects recently but not all of them work.

Technique:
1. Take a panorama with the horizon level - it's best with a uniform foreground and clean sky (see extra)
2. Run the off-set filter to make sure the L and R edges line up
3. Adjust the proportions so the image is square
4. Flip the image vertically
5. Run the Polar Coordinates filter