see also:

• example images at sphericalpanoramas.com
• stereographic projection in fisheye lenses
• panorama

• 360 degree panoramas can be:
  • cylindrical - eg. not include detail high or low - as with most stitched panoramas
  • spherical - includes everything - usually requires stitched images taken with fisheye lenses
  • Little Planet style - converted into a circular image

• Joe Reifer's tutorial
• https://www.ptgui.com/info/spherical_panorama.html
• howtoshoot360.com's video tutorial by Florian Knorn

• generally start with 360 degree cylindrical panoramic image with at least 2:1 aspect ratio and left and right edges matching but can use any image where left and right edges match up (eg. islands)
• ensure bottom quarter of image has little detail eg. sand
• ensure upper quarter of image has little detail eg. blue sky
• ensure horizon is exactly horizontal
• then post-process:
  • stretch image to 1:1 ratio so it is a perfect square
  • rotate image 180deg so it is upside down
  • in PS, apply polar filter (Filter > Distort > Polar Coordinates) and select Rectangular to Polar
    • or in Gimp, use Filters > Distorts > Polar Coords
  • rotate as desired
  • adjust contrast, etc

Image courtesy of PTgui

• PTgui software
• [[http://content.photojojo.com/tutorials/create-your-own-panorama-planets/|