Début de discussion sur identification des doigts

diff --git a/tex/3-input.tex b/tex/3-input.tex
index 826d598f6bfb344195de3d5dc0df7fbebac32c14..33916637e6c5d3b27817a08bceb1a910ecce3125 100644 (file)
--- a/tex/3-input.tex
+++ b/tex/3-input.tex
@@ -624,7 +624,7 @@ The \reffig{fig:hotfingers} shows how we applied this principle to multi-touch i
 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.
+In this example pressing 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.
@@ -645,7 +645,22 @@ Another crib sheet shows an icon representing this constraint.
 
 \subsubsection{Discussion}
 
-Discoverability
+One of the key issues of this kind of system is the discoverability of the available commands.
+The \reffig{fig:hotfingers-helps} shows the visual feedforward items we use to promote the discoverability of commands.
+On the left, when all fingers touch the surface, bubbles show all the possible chords associated with modifiers or commands.
+On the left, crib sheets represent the visual icons of available commands or or constraints for the current chord of the left hand.
+
+Linear menus and toolbars in desktop application show, in principle, all the available commands of an application.
+In our case, the visual representation of commands is only available on demand.
+The command mapping and constraints change in real time as the users press or releases fingers.
+It encourages users to explore the system and discover the available commands.
+This exploration would be an issue if the explorable input space was too large.
+However, we essentially use one-hand chords.
+There are therefore $C_k^5$ possible chords with $k$ fingers, which gives 5 combinations of one or four fingers, and 10 combinations of 2 or 3 fingers.
+Therefore there are $5+10+10+5=30$ modifier chords for a maximum of $150$ single finger commands with the right hand.
+We assume this is a reasonnable size for an explorable input space.
+However, we did not conduct a user study to evaluate this aspect.
+
 \begin{figure}[htb]
   \centering
   \includegraphics[height=3.3cm]{figures/hotfingers-help}
@@ -657,6 +672,8 @@ Discoverability
   \caption[Discoverability features for FingerCuts.]{Discoverability features for FingerCuts. Users can see all the available commands when touching the surface with all their fingers. Crib sheets show the avaiable commands and constraints when fingers of the left hand are touching the surface.}
 \end{figure}
 
+
+
 \subsection{Interaction in VR}
 \label{sec:interactionvr}