Light on Walls: Projection Mapping and LED Screens for a Village
A Ghost in a Ride
In 1969, Disneyland opened a ride called the Haunted Mansion. Near the end, the cars pass a graveyard where a group of stone busts sing a cheerful song about ghosts. The busts are blank, featureless sculptures. The faces, the moving eyes and mouths, are film footage of real singers projected onto them from hidden projectors. Because the film matches the shape of the sculpture, the faces appear to live inside the stone.
That's widely cited as one of the earliest examples of what is now called projection mapping. Projecting images onto something that isn't a flat screen, and shaping the image so it fits the object perfectly. Today it's how cathedrals come alive at light festivals, how car launches make vehicles appear to melt and reform, and how stage sets change from forest to city in a second.
It's also the most obvious, most dramatic thing you can do with the Hippos in the haul. So this episode is about how projection mapping actually works, what equipment you'd need, how LED walls compare, and what would make sense at the scale of a village in Jämtland rather than a stadium in London.
Projectors, the Three Numbers That Matter
When you shop for a projector, there are dozens of specifications. For mapping, three numbers matter most.
The first is brightness, measured in lumens. Projected light has to compete with whatever other light is around. A dark living room needs very little. A stage under show lighting needs a lot. A barn wall outdoors at dusk in August needs a great deal more than you'd expect. Home cinema projectors are typically a few thousand lumens. Event projectors used for mapping buildings go from around ten thousand into the tens of thousands, and big festivals stack several together.
There's a useful twist here. Big rental companies replace their projectors regularly, and older ten thousand lumen units come up secondhand at prices that would have sounded absurd a few years ago. Much like the Hippos, they've fallen off the professional cliff and landed in hobbyist territory.
The second number is throw ratio. It tells you how far back the projector needs to be for a given picture width. A throw ratio of 2 means that to make a picture 3 metres wide, the projector stands 6 metres away. Short throw projectors can make a big image from close up, useful indoors. Long throw lenses let you stand far back, useful for a building facade. If you plan to map the side of a barn, the throw ratio decides where the projector has to stand, and whether that spot is in a field, a car park or the middle of a road.
The third is resolution, but it matters less than you might think. A huge projected image viewed from across a field looks sharp even at modest resolution. Brightness and placement beat pixels almost every time.
Why Black Is Invisible
Here is the single most important idea in projection mapping. Black doesn't project.
A projector can only add light. Wherever the image is black, the projector sends nothing, and the surface just looks like itself. That means the content for a mapping project is designed around the surface, not on a rectangular canvas. You build a picture that is mostly black, with light falling only where you want it. Light on the window frames. Light along the roofline. A glow that crawls up one corner. The building itself provides the rest.
You're not putting a video on a wall. You're painting the wall with light, and the wall is half the artwork.
The workflow is straightforward. Put the projector where it'll be on the night. Project a plain white image and photograph the surface from right next to the projector lens, so the photo sees exactly what the projector sees. Bring that photo into the media server or a design program, and draw shapes, called masks, over every window, door, beam and edge. Then make content that fits those shapes. When it plays back, the light lands precisely on the architecture.
Media servers like the Hippos were built for exactly this. They can warp an image to fix distortion from an angled projector. They can mask out areas. And they can blend two or more projectors together, overlapping the edges and fading each one smoothly into the next so the join disappears. That's called edge blending, and it's how a wall too wide for one projector becomes one continuous picture.
Content, Where the Real Work Is
The hardware is the easy part now. The content takes the time. Professional mapping shows are made by animators, often in tools like Cinema 4D, Blender or After Effects, rendered to fit the exact shape of the building. A five minute show on a cathedral can take a small team weeks.
But at village scale, you can cheat beautifully. Simple ideas land best. Outline every edge of a building in a line of light that draws itself around. Fill the windows one by one as if people are moving through the house. Make the wall look as if it's cracking and falling away, revealing a starry sky behind. Project slow falling snow on a summer night. Or a giant moose that walks across the barn and looks at the audience. None of these needs advanced animation, and all of them make people gasp.
And if you want the lazy option that still impresses, project live content. A camera feed of the crowd, a real-time weather visual, the scores from a Game Fair competition, all mapped onto the wall. The Hippos can take live inputs through those capture cards, which brings the whole haul together.
LED Walls, the Other Way to Make Light
The alternative to projection is an LED wall. Instead of throwing light at a surface, you build the surface out of light. Modular panels, called cabinets, each typically around half a metre square, covered in tiny red, green and blue LEDs, bolted together into a wall of any size.
The key number for LED is pixel pitch, the distance between the centres of two neighbouring pixels, measured in millimetres. Small pitch means more pixels and a sharper picture up close, and a much higher price. Large pitch is cheaper and looks fine from further away. A rough rule of thumb used in the industry is that the comfortable minimum viewing distance in metres is about the same as the pitch in millimetres. A 4 millimetre wall looks good from about 4 metres back. A 10 millimetre wall is for audiences across a field.
The other big difference is brightness. Indoor LED panels are comfortably brighter than most projectors. Outdoor panels are dramatically brighter, bright enough to fight direct sunlight, which no projector can do. That's why festival main stages use LED and light festivals at night use projection.
An LED wall has its own hidden electronics. A sending card or video processor takes the picture from a computer or media server and splits it into data for each cabinet. Each cabinet has a receiving card that drives its own LEDs. Names like Novastar and Colorlight dominate that world. And LED walls are heavy, power hungry and need proper rigging, which is why rental companies charge serious money for them.
What Makes Sense for Kall
So, projector or LED, for a village with a garage full of Hippos?
For a night event, projection wins on almost every count. It's cheaper, it's lighter, it can cover a whole building, and it has the magic of transforming something real. One good secondhand event projector, a Hippo, a laptop and a weekend of making content could give Game Fair or a midwinter event something genuinely memorable.
For daylight events, or for PartyPär rentals where a screen needs to be bright and reliable, a small LED wall is the more practical product. Even a modest one, a few cabinets wide, is something rental customers understand and want. The Hippos would drive it perfectly.
Projection is a show. LED is a screen. Decide which one you're building before you buy anything.
And there's a middle path that costs almost nothing. Start indoors. A cheap projector in the garage, aimed at a pile of white boxes stacked in an interesting shape. Map them, light them, make them pulse to music. It's how most mapping artists started, and it teaches every skill you'd need for a barn or a church. All you need is already in your car, except the projector, and Tradera has plenty.
Painting a Village With Light
There's something fitting about this kind of technology ending up in a small place. Projection mapping has always been about making people look again at buildings they walk past every day. In a city, that's a cathedral on a light festival weekend. In Kall, it could be the bygdegård, a barn, the old school, a cliff above the lake.
The tools to do it used to belong only to touring productions and TV studios. Now some of them are sitting in a Hyundai somewhere in Norrland, still smelling faintly of a Stockholm equipment room. The Haunted Mansion busts sang for the first time in 1969. With a bit of patience, a moose could walk across a Jämtland barn wall next summer, and the whole village would come out to watch.