Lately we’ve been working with schools across North America who want to create an interactive wall in their gym or recreational activity room. These walls are created by projecting images in a wall, and using a camera to detect things like balls hitting the wall.
With Lumo Play software, you can turn a large area of wall into a game that many children can play together by throwing balls or soft objects at the wall. Here’s an example of one of our interactive wall games being tested in our demo room:
Most schools already own most of the equipment needed to do this, but setting up a system is a little bit more challenging, and there are a few questions that come up frequently when we’re discussing these systems with our customers. Hopefully this information will help clarify how interactive wall systems work, and how you can bring on into your classroom or school.
How Does It Work?
An interactive wall projection system requires three main things:
You can learn more about Lumo Play’s recommended hardware and find shopping lists on our Help website.
Lumo Play software is installed on a Windows computer, and connected to a projector. The software allows you to calibrate a 3D camera so it will detect and respond to motion directly in front of the wall.
When balls or other objects are thrown at the wall, the game will react.
Objects and people that are not in the detection range will not cause the game to react. However, these things may cause shadows.
The easiest way to avoid shadows is to use an ultra short throw projector, but this is not a good idea if kids are throwing harder objects at the wall, you will need to install a metal enclosure over the projector to prevent it from accidentally being hit and damaged. because the projector will be in the line of action and may be hit. The cage can be hand-made in a metal or woodworking shops class, or purchased from an audio visual supply company like Chief.
If you are unable to permanently mount an ultra short projector to the wall with a protective cage, you can use a short throw projector (with a throw ratio of as close to 1:1 as possible - this means the projected image will be 1 ft diagonal when the projector is 1 ft from the wall, 2ft diagonal at 2ft etc...).
You should look for a projector that includes lens shift and keystone features. This will enable you to set up your system so the bottom of the projected image will sit exactly at or just above a direct line from the lens to the wall.
In a gym, you will mount the projector upside down, either directly to a ceiling, to a column ceiling mount (which can also be purchased from Chief), or to a portable lighting stand. The top of the projection should be in direct line with the lens, and the rest of the image is cast at an angle.
Portable lighting stands can be purchased inexpensively from DJ and theatre supply stores, but they require special mounting equipment to connect the projector to the stand pipe. You can use a custom mount bracket like this one, or you can modify a regular projector mount pretty easily by attaching the mount to a piece of plywood, and getting a few hose clamps (usually used to tighten plumbing or ducting) to attach the plywood to the lighting truss bar.
You should always build in a safeguard in case these attachments fail, so It’s recommended that you also use a chain around the top of the bar as well, which is firmly secured to the projector mount in at least two corners.
Lastly, if you use a portable lighting stand, it’s very important that you use weights (typically sandbags) to ensure the entire stand does not topple over accidentally. Sandbags can cost $15 - $30 each, but you can easily make your own sandbags.
The largest area that recommended 3D cameras can track with precision is around 10'-12' diagonal. For wall installations where you want the tracking to respond to thrown objects, 12' max is recommended.
Projector and Camera
Position the projector and the camera about 12' from the wall, raised above the heads of the tallest child standing. This will also help with shadow control.
You should mount the camera either to the same mounting bracket as the projector, or onto the lighting stand, depending on you chosen mount solution.
The computer will need to be within 4 - 6 feet of the projector and the camera, because using a USB extension cable for your 3D camera can cause latency. Luckily, there are many clever ways to make a suspended laptop shelf, as seen in the picture above. If you prefer to install something more professional, you can purchase a laptop shelf designed to clamp to a mounting stand, and attach it to the same support that your projector is mounted to.
How Much Does It Cost?
Lumo Play software can be downloaded from www.lumoplay.com. There is a free 30 day trial. We sell a $99 Personal software license at-cost. This is intended for schools, not for profits, and small business who cannot afford the Pro license ($599).
The typical cost for the hardware in these types of installations is between $1200 - $5000, depending on how bright the projector is, how fast a computer you buy, and what mounting solution you choose.
If you decide to hire a company to perform the installation for you, expect to pay 25% - 50% more. Installing interactive projection systems yourself will save you a lot of money. :)