cylindrical projection image courtesy of:
https://www.eso.org/public/images/eso0932a/

Blender.org method of rendering skybox:
https://www.katsbits.com/tutorials/blender/render-skybox.php
- blender tips to create skybox
Additional steps:
	a) more details on blender order of subimages in 3x2:
        top row:     left  front  right
        bottom row: bottom  top   back
    b) use gimp box select with 512 pixel chucks to extract 6 sub images
	c) flip all 6 sub images horizontally in gimp