In this work we were interested \defword{finger identification}.
It is an additional hand gesture property, which says which finger of which hand produced a given contact point.
There is currently no technology that sense this property directly in consumer electronic products.
-A workaround is to ask users to press all finngers before releasing some of them \cite{lepinski10}.
+A workaround is to ask users to press all fingers before releasing some of them \cite{lepinski10}.
Some projects use a different processing of sensed data.
For example, the old generations tabletops used an infrared projector under a translucent surface, pointed towards the user.
An infrared camera sensed the reflection of the infrared light that created blobs at contact points.
This is particularly useful because multitouch applications typically cannot provide as many commands as desktop applications.
For example, in 2014 Wagner \etal report that there were 648 commands in Adobe Photoshop’s menus compared to 35 commands on the tablet version.
Interaction techniques that use finger identification is a solution.
-However the input space is huge: $2^{10}$ combinations of fingers, to which we can add gestures.
+However the input space is huge: $2^{10}-1$ fingers chords, to which we can add gestures.
We will discuss how we leverage this new input space in a systematic way.
\subsubsection{Prototyping apparatus}
-This project is a typical HCI project in which we investigate the benefits and limitation of an interaction paradigm befoer the technology is ready to implement it in consumer electronics products.
+This project is a typical HCI project in which we investigate the benefits and limitation of an interaction paradigm before the technology is ready to implement it in consumer electronics products.
The advantage is that research for such a technology will happen only if and when the benefits will balance the cost.
Even if such technology is not ready yet, the HCI community regularly uses alternative technologies that necessarrily make compromises.
In some cases we just imagine the technology is there and works perfectly.
\caption[Finger identification prototypes.]{Three implementations of finger identification prototypes. The first one uses gametracks to locate fingers on a tabletop. The two other ones use color markers with a camera to track fingers on a tablet and a smartphone.}
\end{figure}
-The \reffig{fig:hotfingers-prototypes} shows the three prototypes.
+The \reffig{fig:hotfingers-prototypes} shows our three prototypes \cite{goguey14,goguey14a,goguey17}.
The tabletop prototype combines two sources of information.
The first one is the 2D coordinates of the contact points.
The second one is the 3D position of every finger that we sense with GameTraks\footnote{\href{https://en.wikipedia.org/wiki/Gametrak}{https://en.wikipedia.org/wiki/Gametrak}}.
\subsubsection{Input vocabulary}
+In this project we leveraged the input vocabulary of finger identification for command selection as well as the direct manipulation of the command parameters \cite{goguey14,goguey14a,goguey17}.
+Without finger identification, the input space is just the number of contacts, between 1 and 10 for one user, and coordinates for each contact point.
+With finger identification, the theoretical input space much larger: each finger can either be pressed or not, which leads to $2^{10}-1$ possibilities.
+However, chords with too many fingers are less likely used.
+For a given number of fingers $k$ there are still $C_k^{10}$ possible combinations.
+This leads to 45 combinations of 2 fingers and 120 combinations of 3 fingers.
+People cannot perform all chords efficiently because of biomechanical constraints~\cite{ghomi13}.
+However, this input space remains still high therefore the design of a command selection technique requires a systematic approach.
+
+The inspiration for our design rationale stems from command selection with keyboard shortcuts.
+They use modifier keys and an alphanumeric key.
+Different combinations of modifier keys change the command activated with a given alphanumeric key.
+Then, when the associated action is being executed the users can apply constraints with modifier keys.
+The \reffig{fig:hotfingers} shows how we applied this principle to multi-touch interaction with finger identification.
+The users start with touching the surface with their left hand.
+Some of the possible chords enable the selection of commands with the right hand.
+A crib sheet shows icons representing the five commands mapped to each of the five fingers of the right hand.
+In this example prressing both the thumb and index finger maps drawing commands to fingers.
+The user draws a rectangle by using the command associated to the middle finger.
+The initial contact point of the middle finger of the right hand defines one corner of the rectangle, and the opposite corner is adjusted continuously with direct manipulation.
+During this step, the users can lift their left hand and continue to adjust the rectangle.
+Now, they may want to apply constraints.
+To do so, they touch the surface with the left hand.
+In this example the middle finger sets the initial contact point as the center of the rectangle rather than the first corner.
+Another crib sheet shows an icon representing this constraint.
+
+%users can lift the right hand during this process but also put it back to apply constraints, like perfect shape, etc.
-FingerCuts \cite{goguey14,goguey14a,goguey17}
-
-Leverages finger identification for command selection and direct manipulation of parameters.
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projects / hdr.git / commitdiff