Dancing on The Ceiling with a Halfdome

Have you ever wondered how you could create an amazing light show that would fill an entire room with just a mirror?

The thought hadn’t really crossed my mind until I saw this amazing geodesic dome at the Chaos Communication Camp in the summer of 2023:

Photo of a geodesic dome which is illuminated from the inside by a video projection of a banana floating around behind a backdrop of black triangles that appear to be connected together

I discovered that you can achieve this kind of effect using something called a halfdome mirror. Halfdome mirrors are normally used for safety and security, e.g. attached to walls or ceilings to give extra visibility at entries and exits. They look like this, although the geodesic dome tent is optional…

Photo of a halfdome mirror in a geodesic dome tent. There is a projector pointing at it and some reflected blue light which looks like laser beams. If you look really closely you might see a middle aged person crouched down on the floor taking a photo with their phone

It turns out that if you point a light source (such as a projector playing a video) at a halfdome pushed up against a wall, it produces the most wonderfully distorted reflections which can pretty much fill up an entire room. Like this clip of the video for Dreamsicle Bomb by Black Moth Super Rainbow in my living room:

Video showing colourful artistic graphics being projected onto the walls and ceiling of a room from a projector which is reflecting off a halfdome. Two sock-clad feet are visible at the bottom of the frame if you look closely.

OK, so you do need that light source - but if you have access to a projector or something else that produces interesting patterns and colours then the halfdome mirror is fairly inexpensive at around £30-£40. Alternatively, you could make your own wonky mirrored surface and really lean into the whole DIY aesthetic!

Note that further processing is required to take an normal image or video and warp it to display well when mirrored inside a dome type structure. Paul Bourke has produced a highly detailed writeup and also created some software in case you’re interested.

Check out Paul Bourke's site