26.1183GPPRelease 17TSVirtual Reality (VR) profiles for streaming applications
Equirectangular mapping is the most commonly used mapping from spherical video to a 2D texture signal. The mapping is bijective, i.e. it may be expressed in both directions and is illustrated in Figure A.2.
Figure A.2: Mapping of spherical video to a 2D texture signal
ERP has only one face and the face index f for ERP is always set to 0. The sphere coordinates (ϕ, θ) for a sample location (i, j), in degrees, are given by the following equations:
ϕ = (0.5 – i/pictureWidth)*360
θ = (0.5 – j/pictureHeight)*180
Finally, (X, Y, Z) can be calculated from the equations given above.