Impact of $-family

Recognizers: $1 • $N • $P • $P+ • $Q • Impact of $-family
Tools: GECKo • GREAT • GHoST • AGATe

Impact of $-family

Gesture recognition used to be difficult, arcane, and specialized. Then in 2007 came the $1 recognizer and the $-family that followed. Now gestures are easy to add to any user interface.

The $-family recognizers, of which $1, $N, $P, and $Q are canonical members, along with enhancements Protractor and $P+, have had significant impact on the deployment of gestures in interactive prototypes. The $1 paper, published at ACM UIST 2007, is the 3rd most-cited UIST paper according to the ACM Digital Library. Google Scholar shows the $1 paper being cited 818 times. Beyond citations, $1 has been implemented in scores of projects. Its use has gone beyond its initial intent for stroke-gesture recognition to things like hand-pose recognition.

The $1 paper and its siblings led to numerous follow-ons by other researchers, leading to the "extended $-family" of technologies. All adopt the same philosophy espoused by the original $1 paper: to take what are typically complex, arcane technologies understood only by specialists and make them easy to convey, implement, and deploy on any platform for non-specialists whose objective is quickly enhancing interactivity. Accordingly, the $1 paper began a trend, followed by other $-family publications, of putting the entire pseudocode necessary for implementation directly in their publications.

Beyond academic impact, $1 and the $-family have been rapidly absorbed into industry prototypes. For example:

Within a year of $1's publication, Mr. Spiff's Revenge by POW Studios won Best Windows Game in the 2008 Dr. Dobb's Challenge. It used $1 for creating shields (circles), launching fireballs (arcs), drinking potions (hearts), and smashing all enemies ("pow").
In the same year, $1 was reviewed by Make:, a popular DIY website for hackers and hobbyists.
Microsoft used $N to recognize multistroke gestures on their PocketTouch device, which enabled gesture-sensing through a pants pocket for quick, ambient interactions.
German firm Prefrontal Cortex employed $P for gesture control in Ombre Fabula, a gesture-controlled interactive shadow play. The prototype won 2nd place at the 2014 Intel RealSense App Challenge.

The extended $-family

$1 and the other canonical $-family recognizers inspired other researchers to develop follow-ons that share the $-family motivation. We and their authors consider the following to be the "extended family" of the $-family recognizers. They are listed in chronological order:

$3 by Kratz & Rohs (2010)
Protractor3D by Kratz & Rohs (2011)
Quick$ by Reaver et al. (2011)
1¢ by Herold & Stahovich (2012)
1€ by Casiez et al. (2012)
1F by Vatavu (2012)
Penny Pincher by Taranta II & LaViola, Jr. (2015)
$-family prototype selection by Pittman et al. (2016)
3¢ by Caputo et al. (2017)
Jackknife by Taranta II et al. (2017)
CircGR by Balcazar et al. (2017)

Some examples of the $-family in industry prototypes

The $-family recognizers have been used in industry prototypes. Below are five nice examples:

Mr. Spiff's Revenge by POW Studios ($1, 2008)
AlphaCount by Olivier Brand ($N, 2010)
PocketTouch by Microsoft Research and CMU ($N, 2011)
Ombre Fabula by Prefrontal Cortex ($P, 2014)
MageVR by Binh Vo ($P, 2018)

Some examples of the $-family in others' research projects [Google Scholar for $1]

Many research projects have used the $-family recognizers, especially $1. Below are six projects by others:

Eden by Kin et al. ($1, 2011)
Air+Touch by Chen et al. ($1, 2014)
Expanding the Input Expressivity of Smartwatches... by Xiao et al. ($1, 2014)
PalmGesture by Wang et al. ($N, 2015)
Using hand gestures to fly a drone by Qorashi ($P, 2015)
Finger-Aware Shortcuts by Zheng & Vogel ($1, 2016)

$-family implementations by others

Over the years, many developers have sent their own implementations of our $-family recognizers in various programming languages. We make no representation of the correctness or completeness of these implementations, but offer them here "as is." (Have one to add? Email wobbrock@uw.edu.)

$1

github $-family repositories in many languages
MotionCAPTCHA jQuery plugin, by Joss Crowcroft
GLGestureRecognizer, an Objective-C version for iPhone, by Adam Preble
$1 for VVV, by motzi
Flash Actionscript version, by Christoph Ketzler
Flash Actionscript 3 demo, by Felix Raab
Processing version, by Darius Morawiec
Java SE/ME version, by Alex Olwal [YouTube]
MicroDollar: $1 in C++ w/optimizations for embedded hardware, by Alex Olwal
Java version, by Norman Papernick
C# version for Windows 7, by Kevin Marshall
Python version, by Charlie Von Metzradt
Python version, by Shaun K. Kane
Python version, by Mike O'Brien
C++ version, by Baylor Wetzel
C++ version, by Ishikawa
X3D version, by Michael Zöllner
JSXGraph demo, by Alfred Wassermann

$N

Sketch uses a C# version, by Aaron Wolin et al.
WTMGlyph, a version for iOS by Brit Gardner
jQuery gesture, a version in JavaScript by Adrien Gibrat
C++ version, by Rajat Goyal
Java version, by Jan Sonnenberg

$P

C# version for Unity, by Da Viking Code
$P for VVV, by ethermammoth
Python version, by Simon Waloschek
Objective-C version, by Felix Raab
Objective-C version for LeapMotion, by qorashi
Java version, by David White
Java version, by Michael D. Manson
Java version for Android, by Michael D. Manson
JavaScript version for npm, by Francois Laberge