Thank you two for your answers.
Vishwas: It's true, the player create a VR stereoscope from a single image. And that gives you a 2D "flat" VR. On the Krpano VR demo page, there is also 3D panoramas. Those are 3D, you can see the depth of things the same way you do when you watch a 3D movie in cinema. As far as I know, to do that, you need to caputre two pictures. One for the left eye and one for the right eye. A little about stereoscropie here:
https://fr.wikipedia.org/wiki/St%C3%A9r%C3%A9oscopie
But I haven't found a satisfying method to do it with krpano yet.
I'll pursue my little research.
Cheers !