Early experiments on “Portal Pictures
A way to display (semi)spherical panoramas

A few days ago I got contacted by several people about the following reel, showing Portal Pictures by the TikTok user Omnisteven. They asked me if this particular kind of display can only work with paintings or also with photographs and there was a fruitful discussion in the 360º photographers community I am a member of.

Portal Pictures presents a way to display panoramas in “analog VR”, able to show an immersive image without distortion on the inner surface of an hemisphere. When the image is drawn or printed with the right distortion, the viewer can enjoy the anamorphosis from zenith to nadir. This effect can be achieved with any spherical panorama by extracting half a hemisphere from the 360º image or by projecting it onto a circular 180º fisheye projection with specialized panoramic software.

I made a test with one of my drawings, using a half hemisphere in sinusoidal-interrupted projection printed on an A4 paper. Although the template uses an origami folding method that is supposed to work on the outside, it is possible to fold it sideways and get the “portal image” effect.

The idea of having an immersive view of a painted hemisphere is very intriguing and it could be a good solution for displaying panoramas in an immersive installation.

I also post an article by Paul Bourke, who has been experimenting with a hemispheric dome projection called iDome, which uses a convex mirror to project images onto a hemispheric concave surface. This system allows to have multiple panoramas on the same dome. However, it is not a fully circular projection because it lacks zenith and nadir.