Most often, a 3D tour is a series of 360° images, also called photospheres, panoramas, or panos, where a user can navigate from one 360° image to another. There is an opinion that simply using 360° images without an underlying 3D mesh, or 3D point cloud collected by a camera, is not enough for such a presentation to be called a 3D tour, so an explanation is needed.
The term 3D, shorthand for three dimensional, means having three degrees of freedom in which a user can move. In each 360° image a user can look left-right and up-down and these degrees of freedom add up to two dimensions. In addition, a user can move between 360° images, zooming in and out of the images during such transitions. This degree of freedom adds yet another dimension, resulting in the experience of moving through 3D space. Because of that, the term “3D tour” is well justified for tours made using connected 360° images.
Another way to show a 3D tour is to use a 3D mesh with image textures applied to it. This approach is generally not used in a web browser for rendering real physical spaces captured with a camera, due to the high complexity of 3D mesh for the limited resources of a web browser. However, computer-generated 3D environments are often rendered in web browsers using the textured 3D mesh approach because in such cases the 3D mesh is a lot simpler.
The representative 3D tour technologies we will examine in this article are produced by iGUIDE, Matterport, Leica, Cupix, InsideMaps, Ricoh, Insta360, Immoviewer, and Zillow.