According to the release notes, only flat surfaces can be transformed into 3d space and that HMTL5 only supports cubicle panoramic images:
Viewer support - Cubical only
The krpano HTML5 Viewer itself currently only supports cubical panoramic images.
Why? ⇒ With the HTML5 CSS 3D transforms it is only possible to transform flat html surfaces in 3D space. And this only allows to the usage of panoramic formats with flat surfaces like the six flat sides of a cubical pano.It also mentions that spherical, cylindrical and cubical images can be converted to cubes, though on if they have hfov=360
Tools support - Spherical, Cylindrical and Cubical
To be able to use also other formats like spherical or cylindrical, the krpano Tools and Droplets can be used. They can convert such images (only images with hfov=360) automatically to cubical images and also set automatically viewing-range-limitations to avoid seeing the unused parts of the converted cubical images.
What I would really love to know is when single flat images will be supported, or if there is a way to already convert them now? They are not Spherical, Cylindrical or Cubical, so I would imagine they should work.
Thanks,
D