How to do projection mapping with Raspberry Pi

Learn how to use the Pi Cap to do projection mapping with the Raspberry Pi

man demonstrating Raspberry Pi projection mapping using a Pi Cap

Chances are you have seen projection mapping either in a video or in real life. There are some amazing videos of projection mapping and always in a different environment: either at corporate events, at music festival or concert or even in public, like this one in iconic New York City. Wherever projection mapping is done, it’s unique and never fails to amaze the viewers.

Interactive projection mapping with Electric Paint is our favorite immersive experience that makes use of our technology. We’ve seen so many exciting projects, done either with the Touch Board or the Pi Cap, but in this tutorial, we explain how to create projection mapping with the Pi Cap. We are using Electric Paint to design sensors on the wall and when these sensors are touched, they are registered by the Pi Cap, which triggers the animation.

You can use any Raspberry Pi that has a 40-pin GPIO, but we use the Raspberry Pi Zero W as it allows us to connect directly to the Pi Cap on a flat surface and cold solder to the Pi Cap. The Raspberry Pi Zero W is connected to a computer via SSH and takes OSC commands via Processing. These OSC commands are sent to the projection mapping software, in this case, MadMapper. You can download Processing for free from the Processing website and a trial version of the mapping software MadMapper from the MadMapper website.

The Pi Cap has the benefit that it is a Raspberry Pi add-on and therefore has wireless communication. You don’t need the computer connected to the Raspberry Pi for this project. However, in comparison to the Touch Board and Interactive Wall Kit, it is less stable and trickier to set-up.

Our community has produced many stunning projection mapping installations and depending on the venue and the audience, they have changed the experience. Find out more in our Blog section.

Step 1 Set up the Pi Cap and computer

Attach the Pi Zero W to the Pi Cap and to power. If this is your first time using a Pi Cap, make sure to have it set up first by using the set-up tutorial. Throughout this project, we are connected to the Pi Cap from our laptop via SSH.

The code we are running is “datastream-osc.py”. Before you can run it, you need to know the hostname of the computer that is going to run the projection mapping software and is receiving the commands from the Raspberry Pi. The hostname depends on which operating system you are using, so we recommend doing a quick Google search in order to find out the name. Once you have the name, run the code on the Raspberry Pi Zero W with

./PiCapExamples/Python/picap-datastream-osc-py/run -h HOSTNAME

where “HOSTNAME” is the hostname of your computer.

Step 2 Set up Processing and run the code

Next, you need to download Processing, if you haven’t installed it yet. Once downloaded, open Processing, and check its default document folder under

Processing→Preferences…

Then, download the Processing sketch. Unzip the file and move the folder “picap_madmapper” to the location you just looked up and open the file. Head to

Sketch→Import Library→Add Library…

In the search field, look for “oscP5” then click “Install”. Once you have installed the libraries, click on run to launch the sketch. When you touch electrodes 0 or 1 on your Pi Cap, it should write “Electrode 0 was touched” and “Electrode 1 was touched” in the console window.

Step 3 Connect the Pi Cap to MadMapper

Next, you need to set-up your projection mapping software. We’re using MadMapper, for which you can download a trial version from the MadMapper website. If you want you can download two sample animations.

Change the play setting of the videos to “Play the movie to the end of the loop and pause”. Touch the electrode E0 and E1 again, you should see the animation play in MadMapper!

Step 4 Prepare the surface

With most of the hardware done, we now need to make art and create the interactive surface, where you want projection mapping to take place. In this example, we use a piece of white cardboard. We are going to paint the artwork with the help of two stencils, which we attach to the wall.

Before we apply the paint, we need to create a connection to the back and to the Pi Cap. In order to do so, we use two black nails and pierce the cardboard somewhere within our stencils. On the backside of the cardboard, we need to connect the nails to the Pi Cap with a conductive material.

Attach the Pi Cap somewhere along the bottom of the wall where you can still connect it to power later. We use copper tape to connect to the Pi Cap; pierce the tape through the screws, and add a bit of Electric Paint to hold the connection. Cold solder the other end of the copper tape to the Pi Cap with Electric Paint.

We can now paint the sensors with Electric Paint by simply painting the stencils with a brush. Leave the paint to dry and in the meantime, we can transform the animations in MadMapper. You can find full instructions for creating stencils in our how to stencil with Electric Paint tutorial.

Step 5 Prepare the animations in MadMapper

Back on your computer, position the projector so that it shines onto your surface and connect it to your computer. Open MadMapper and enter the “Full Screen Mode” of MadMapper. Move and scale the video to your liking, checking with the output of the projector if the visual is fitting nicely with the sensor.

Step 6 Touch the paint and watch the animation

Now everything has been assembled and we can give the projection mapping a test. Remember, at this point, we should have the OSC code running on the Pi Cap, the Processing sketch running on your computer and have MadMapper open with the animations. Try touching the paint on your surface and watch the animation unfold!

Step 7 Next steps

If you want to change one video animation or more, then have a look inside the Processing sketch. If you look inside the code you can find the lines “mediasList[0] = “bubble_animation.mp4″;” and “mediasList[1] = “bubble_animation.mp4″;”. The number inside the square bracket corresponds to the electrode that is touched, so for example when touching electrode 0, MadMapper will play “bubble_animation.mp4”. If you want to use your own animation, you need to change the name in Processing. Therefore, if you want to include “animation1.mp4”, you need to include this filename in the Processing sketch, e.g. “mediasList[0] = “animation1.mp4″;”.

If you want to add sound to the project, just add the sound to the animation and let the projection mapping software play it.

There are so many possibilities to take this project further, for example, instead of having the surface vertically, you can have it horizontally, and have an interactive table. You could even embed the paint in a sculpture!

We would love to see what you make, so please share your projects with us on social media, either via Instagram or Twitter or send us an email at info@bareconductive.com.