The invention relates to a solution wherein a bitstream defining a presentation is generated, the presentation comprising an omnidirectional visual media content and a visual overlay. A first relative distance of the omnidirectional visual media content and a second relative distance of the visual overlay are indicated in the bitstream. Metadata indicative of a scale applicable to convert the first relative distance and the second relative distance to real-world distance units is also associated with the generated bitstream, wherein the scale is for deriving a binocular disparity for the visual overlay. The invention also concerns a solution for decoding the bitstream to obtain data for deriving binocular disparity for the visual overlay.