This panorama is interactive, this isn't.
How do I make my panorama interactive? I guess it's either an EXIF flag or a specific format. Ideally I'm looking for something free which works on Linux. Hugin does not seem to have a setting for this.
I've tried the following command:
exiftool \
-ProjectionType=equirectangular \
-FullPanoWidthPixels'<$ImageWidth' \
-FullPanoHeightPixels'<$ImageHeight' \
-UsePanoramaViewer=True \
-out test1.jpg \
original.jpg
And verified the result:
$ exiftool test1.jpg | grep -e Pano -e Projection
Full Pano Height Pixels : 1061
Full Pano Width Pixels : 22902
Projection Type : equirectangular
Use Panorama Viewer : True
Unfortunately Flickr still shows test 1 as a normal image.
OK, I'm getting somewhere. I tried also resizing it to 2:1 using:
convert -resize 2:1 test1.jpg test2.jpg
Test 2 does show up as a panorama, but looks completely messed up, probably because the original image does not have 180° vertical range.
I then tried to tweak the "Full Pano" pixel settings, but test 3 doesn't look any different. In fact, as you can see in test 4 these settings don't seem to change anything.