Bounce is an augmented reality installation, allowing the user to interact with the system by throwing balls at a projection on the wall.

It was developed as a student project using OpenFrameworks and the included OpenCV-Addon.

Programming and functionalities are quite prototypical.

watch video

• experience with OpenFrameworks
• camera
• projector
• microphone
• balls

In order to compile Bounce you have to:

• download Openframeworks with addons(FAT), compatible to your IDE
• in the OF directory, go to apps/addonsExamples/ and make a copy of allAddonsExample, rename it bounce
• add the source-files from this repository to bounce/src/
• get the media and include it in bounce/bin/data/

Notice: The current version is not able to adapt to size change after being compiled. All buttons and graphics are measured to 1280 x 800, and need to be modified in position and size otherwise. To change the window's size you need to change the windowWidth and windowHeight at main.cpp (line 13 and 14).

• use a projector to throw a screen-projection on a wall. The picture needs to be rectangular, no trapezoidal effect.
• than darker the room and than lighter the projection than better.
• it's not necessary that the camera is directly beside the projector.
• make sure that the camera gets the full screen, but few from the surrounding.
• fasten the microphone as near as possible at the projection, directly on the wall, a contact microphone is best.
• test if you get a sound when throwing a ball against the wall.
• use black beanbags or tennisballs in black duct tape.

start:

• Windows: When starting the program, a console window is opened and gives you a list of camera devices. Type in the ID of the device you want to use.

• MacOS: If you want to choose a device, start from Terminal, otherwise the first available device is chosen.

• Linux: not tested

menu:

• After the start you see the menu
• Mouseclicking has the same effect as a bounce of a ball.
• You can click or bounce on the buttons to start games or calibration.

games:

• The games start immediately or after the first bounce.
• after the game is finished you see a scores table
• on the left side are all-time highscores, on the right side the scores of the last ten players.
• if you get inserted in the highscores, you have to type in your name.
• the highscores get saved in game.txt in the bounce directory

After the launch of Bounce it is nessesary to calibrate before the balls get recognised.

• Click on the calibrate button in the menu.
• Now you see the picture of the camera, if not, no camera is available.
• Direct the camera to the screen or projection, the full application window has to be inside the picture.
• click again and the calibration will start, make sure that nothing moves in the image of the camera.
• at first the system tries to see 4 circles, one in each corner.
• then every single cornerposition gets measured from the application.
• after that you can see the audio-plot of the microphone, make some noise and you see an effect.
• now the application is able to recognise balls thrown at the projection, if not read error-handling.

It is also recommended to calibrate while playing.

• SPACE - pauses/proceeds the game
• M - back to menu
• F - fullscreen
• S - open camera settings window
• C - shows/hides the Console (see console)
• 1 to 5 - shows processed images
• 0 - reset calibration
• ESC - end program

used to change specific values (left bottom)

press 'c' to show/hide

use LEFT and RIGHT arrow to navigate between values and UP and DOWN to change the value

values:

• screenStoreSize - regulates how much pictures from screen get stored, neccessary because cameraImage and screenImage have temporal difference
• camWaitFrames - sets how many frames the system waits from sound to picture, because the microphone is faster than the camera
• threshold - sets how high the brightness difference of a pixel has to be at least between camera- and screenImage to be recognised
• bangLevel - how much energy-change in the audiosignal a bounce has to make to be recognised, symbolised by the red line at the end of calibration mode

bang of ball not loud enough:

• do the calibration as described, till the audioplots appear.
• throw a ball and see if the audioplot goes above the red line.
• if not change the bangLevel at the console, till the ballsound is above the red line.

ball not detected:

• after calibration, throw a ball against the wall
• press '5' to see a gray picture from the camera with the ball on it
• if there is no ball on the picture, you have problems with the microphone maybe
• press '3' to see a black picture whera all differences between screen and camera are white
• the ball should be a white blob in this picture
• if there is more white than the ball, increase the threshold in the console
• if there is no white, decrease the treshold in the console, until you see the ball after throwing.
• if the white is not controllable, adapt the lighting of your room.

projector or camera was moved:

• do the calibration once again