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Commit 9f793b02 authored by Taddeus Kroes's avatar Taddeus Kroes
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Improved report based on feedback.

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docs/data/diagram.tex
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\node [impl, right of=eventserverdots] (tuioserver) {TUIO server};
\node [block, below of=eventserver] (gestureserver) {Gesture erver};
\node [block, below of=eventserver] (gestureserver) {Gesture server};
\path [line] (eventserver) -- node {trigger events of all touch points}(gestureserver);
% Window
......
docs/report.tex
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......@@ -9,7 +9,7 @@
\hypersetup{colorlinks=true,linkcolor=black,urlcolor=blue,citecolor=DarkGreen}
% Title Page
\title{A universal detection mechanism for multi-touch gestures}
\title{A generic architecture for the detection of multi-touch gestures}
\author{Taddeüs Kroes}
\supervisors{Dr. Robert G. Belleman (UvA)}
\signedby{Dr. Robert G. Belleman (UvA)}
......@@ -47,50 +47,44 @@ provides the application framework here, it is undesirable to use an entire
framework like Qt simultaneously only for its multi-touch support.
% Ruw doel
The goal of this project is to define a universal multi-touch event triggering
mechanism. To test the definition, a reference implementation is written in
The goal of this project is to define a generic multi-touch event triggering
architecture. To test the definition, a reference implementation is written in
Python.
% Setting
To test multi-touch interaction properly, a multi-touch device is required.
The University of Amsterdam (UvA) has provided access to a multi-touch table
from PQlabs. The table uses the TUIO protocol \cite{TUIO} to communicate touch
events.
\section{Definition of the problem}
% Hoofdvraag
The goal of this thesis is to create a multi-touch event triggering mechanism
for use in a VTK interactor. The design of the mechanism must be universal.
The goal of this thesis is to a create generic architecture for a
multi-touch event triggering mechanism for use in multi-touch applications.
% Deelvragen
To design such a mechanism properly, the following questions are relevant:
To design such an architecture properly, the following questions are relevant:
\begin{itemize}
\item What is the input of the mechanism? Different touch drivers have
different API's. To be able to support different drivers (which is
highly desirable), there should probably be a translation from the
\item What is the input of the architecture? Different touch drivers
have different API's. To be able to support different drivers
(which is highly desirable), there should be a translation from the
driver API to a fixed input format.
\item How can extendability be accomplished? The set of supported events
should not be limited to a single implementation, but an application
should be able to define its own custom events.
\item How can the mechanism be used by different programming languages?
A universal mechanism should not be limited to be used in only one
language.
\item Can events be shared with multiple processes at the same time? For
example, a network implementation could run as a service instead of
within a single application, triggering events in any application that
needs them.
\item How can extendability be accomplished? The set of supported
events should not be limited to a single implementation, but an
application should be able to define its own custom events.
\item How can the architecture be used by different programming
languages? A generic architecture should not be limited to be used
in only one language.
\item Can events be shared with multiple processes at the same time?
For example, a network implementation could run as a service
instead of within a single application, triggering events in any
application that needs them.
% FIXME: gaan we nog wat doen met onderstaand?
%\item Is performance an issue? For example, an event loop with rotation
% detection could swallow up more processing resources than desired.
\item How can the mechanism be integrated in a VTK interactor?
%\item How can the architecture be integrated in a VTK interactor?
\end{itemize}
% Afbakening
The scope of this thesis includes the design of a universal multi-touch
triggering mechanism, a reference implementation of this design, and its
integration into a VTK interactor. To be successful, the design should
allow for extensions to be added to any implementation.
The scope of this thesis includes the design of a generic multi-touch
triggering architecture, a reference implementation of this design, and its
integration into a test case application. To be successful, the design
should allow for extensions to be added to any implementation.
The reference implementation is a Proof of Concept that translates TUIO
events to some simple touch gestures that are used by a VTK interactor.
......@@ -99,7 +93,7 @@ events.
\section{Structure of this document}
% TODO: pas als het klaar is
% TODO: pas als thesis af is
\chapter{Related work}
......@@ -144,7 +138,7 @@ events.
\section{Processing implementation of simple gestures in Android}
An implementation of a detection mechanism for some simple multi-touch
An implementation of a detection architecture for some simple multi-touch
gestures (tap, double tap, rotation, pinch and drag) using
Processing\footnote{Processing is a Java-based development environment with
an export possibility for Android. See also \url{http://processing.org/.}}
......@@ -155,69 +149,13 @@ events.
the complexity of this class would increase to an undesirable level (as
predicted by the GART article \cite{GART}). However, the detection logic
itself is partially re-used in the reference implementation of the
universal gesture detection mechanism.
\chapter{Preliminary}
\section{The TUIO protocol}
\label{sec:tuio}
The TUIO protocol \cite{TUIO} defines a way to geometrically describe
tangible objects, such as fingers or fiducials on a multi-touch table. The
table used for this thesis uses the protocol in its driver. Object
information is sent to the TUIO UDP port (3333 by default).
For efficiency reasons, the TUIO protocol is encoded using the Open Sound
Control \cite[OSC]{OSC} format. An OSC server/client implementation is
available for Python: pyOSC \cite{pyOSC}.
A Python implementation of the TUIO protocol also exists: pyTUIO
\cite{pyTUIO}. However, the execution of an example script yields an error
regarding Python's built-in \texttt{socket} library. Therefore, the
reference implementation uses the pyOSC package to receive TUIO messages.
The two most important message types of the protocol are ALIVE and SET
messages. An ALIVE message contains the list of session id's that are
currently ``active'', which in the case of multi-touch a table means that
they are touching the screen. A SET message provides geometric information
of a session id, such as position, velocity and acceleration.
Each session id represents an object. The only type of objects on the
multi-touch table are what the TUIO protocol calls ``2DCur'', which is a
(x, y) position on the screen.
ALIVE messages can be used to determine when an object touches and releases
the screen. For example, if a session id was in the previous message but
not in the current, The object it represents has been lifted from the
screen.
SET provide information about movement. In the case of simple (x, y)
positions, only the movement vector of the position itself can be
calculated. For more complex objects such as fiducials, arguments like
rotational position is also included.
ALIVE and SET messages can be combined to create ``point down'', ``point
move'' and ``point up'' events (as used by the \cite[.NET
application]{win7touch}).
TUIO coordinates range from $0.0$ to $1.0$, with $(0.0, 0.0)$ being the
left top corner of the screen and $(1.0, 1.0)$ the right bottom corner. To
focus events within a window, a translation to window coordinates is
required in the client application, as stated by the online specification
\cite{TUIO_specification}:
\begin{quote}
In order to compute the X and Y coordinates for the 2D profiles a TUIO
tracker implementation needs to divide these values by the actual
sensor dimension, while a TUIO client implementation consequently can
scale these values back to the actual screen dimension.
\end{quote}
generic gesture detection architecture.
\section{Analysis}
\section{The Visualization Toolkit}
\label{sec:vtk}
% TODO
\chapter{Experiments}
\chapter{Problem analysis}
% testimplementatie met taps, rotatie en pinch. Hieruit bleek:
% - dat er verschillende manieren zijn om bijv. "rotatie" te
......@@ -235,6 +173,17 @@ events.
% Proof of Concept: VTK interactor
\section{Introduction}
% TODO
TODO: doel v/h experiment
To test multi-touch interaction properly, a multi-touch device is required.
The University of Amsterdam (UvA) has provided access to a multi-touch
table from PQlabs. The table uses the TUIO protocol \cite{TUIO} to
communicate touch events. See appendix \ref{app:tuio} for details regarding
the TUIO protocol.
\section{Experimenting with TUIO and event bindings}
\label{sec:experimental-draw}
......@@ -260,7 +209,7 @@ events.
\end{figure}
One of the first observations is the fact that TUIO's \texttt{SET} messages
use the TUIO coordinate system, as described in section \ref{sec:tuio}.
use the TUIO coordinate system, as described in appendix \ref{app:tuio}.
The test program multiplies these with its own dimensions, thus showing the
entire screen in its window. Also, the implementation only works using the
TUIO protocol. Other drivers are not supported.
......@@ -277,16 +226,13 @@ events.
using all current touch points, there cannot be two or more rotation or
pinch gestures simultaneously. On a large multi-touch table, it is
desirable to support interaction with multiple hands, or multiple persons,
at the same time.
at the same time. This kind of application-specific requirements should be
defined in the application itself, whereas the experimental implementation
defines detection algorithms based on its test program.
Also, the different detection algorithms are all implemented in the same
file, making it complex to read or debug, and difficult to extend.
\section{VTK interactor}
% TODO
% VTK heeft eigen pipeline, mechanisme moet daarnaast draaien
\section{Summary of observations}
\label{sec:observations}
......@@ -297,7 +243,8 @@ events.
\item Gestures that use multiple touch points are using all touch
points (not a subset of them).
\item Code complexity increases when detection algorithms are added.
\item % TODO: VTK interactor observations
\item A multi-touch application can have very specific requirements for
gestures.
\end{itemize}
% -------
......@@ -319,22 +266,26 @@ events.
that can be used in gesture detection algorithms.
% events toewijzen aan GUI window (windows)
\item An application GUI window should be able to receive only events
occuring within that window, and not outside of it.
occurring within that window, and not outside of it.
% scheiden groepen touchpoints voor verschillende gestures (windows)
\item To support multiple objects that are performing different
gestures at the same time, the mechanism must be able to perform
gestures at the same time, the architecture must be able to perform
gesture detection on a subset of the active touch points.
% scheiden van detectiecode voor verschillende gesture types
\item To avoid an increase in code complexity when adding new detection
algorithms, detection code of different gesture types must be
separated.
% extendability
\item The architecture should allow for extension with new detection
algorithms to be added to an implementation. This enables a
programmer to define custom gestures for an application.
\end{itemize}
\section{Components}
Based on the requirements from section \ref{sec:requirements}, a design
for the mechanism has been created. The design consists of a number of
components, each having a specific set of tasks.
for the architecture has been created. The design consists of a number
of components, each having a specific set of tasks.
\subsection{Event server}
......@@ -353,11 +304,12 @@ events.
placed on the screen, moving along the surface of the screen, and being
released from the screen.
A more extended set could also contain the same three events for a
surface touching the screen. However, a surface can have a rotational
property, like the ``fiducials'' type in the TUIO protocol. This
results in as $\{point\_down, point\_move, point\_up, surface\_down,
surface\_move, surface\_up,\\surface\_rotate\}$.
A more extended set could also contain the same three events for an
object touching the screen. However, a object can also have a
rotational property, like the ``fiducials'' type in the TUIO protocol.
This results in $\{point\_down, point\_move, point\_up, object\_down,
object\_move, object\_up,\\object\_rotate\}$.
% TODO: is dit handig? point_down/object_down op 1 of andere manier samenvoegen?
An important note here, is that similar events triggered by different
event servers must have the same event type and parameters. In other
......@@ -367,8 +319,9 @@ events.
The output of an event server implementation should also use a common
coordinate system, that is the coordinate system used by the gesture
server. For example, the reference implementation uses screen
coordinates in pixels, where (0, 0) is the upper left corner of the
screen.
coordinates in pixels, where (0, 0) is the upper left corner and
(\emph{screen width}, \emph{screen height}) the lower right corner of
the screen.
The abstract class definition of the event server should provide some
functionality to detect which driver-specific event server
......@@ -376,11 +329,15 @@ events.
\subsection{Gesture trackers}
A \emph{gesture tracker} detects a single gesture type, given a set of
touch points. If one group of points on the screen is assigned to one
tracker and another group to another tracker, multiple gestures, an be
detected at the same time. For this assignment, the mechanism uses
windows. These will be described in the next section.
Like \cite[the .NET implementation]{win7touch}, the architecture uses a
\emph{gesture tracker} to detect if a sequence of events forms a
particular gesture. A gesture tracker detects and triggers events for a
limited set of gesture types, given a set of touch points. If one group
of touch points is assigned to one tracker and another group to another
tracker, multiple gestures can be detected at the same time. For the
assignment of different groups of touch points to different gesture
trackers, the architecture uses so-called \emph{windows}. These are
described in the next section.
% event binding/triggering
A gesture tracker triggers a gesture event by executing a callback.
......@@ -402,7 +359,7 @@ events.
trackers can be saved in different files, reducing the complexity of
the code in a single file. \\
% extendability
Because tacker defines its own set of gesture types, the application
Because a tracker defines its own set of gesture types, the application
developer can define application-specific trackers (by extending a base
\texttt{GestureTracker} class, for example). In fact, any built-in
gesture trackers of an implementation are also created this way. This
......@@ -415,7 +372,7 @@ events.
A \emph{window} represents a subset of the entire screen surface. The
goal of a window is to restrict the detection of certain gestures to
certain areas. A window contains a list of touch points, and a list of
trackers. A window server (defined in the next section) assigns touch
trackers. A gesture server (defined in the next section) assigns touch
points to a window, but the window itself defines functionality to
check whether a touch point is inside the window. This way, new windows
can be defined to fit over any 2D object used by the application.
......@@ -490,7 +447,12 @@ events.
start server
\end{verbatim}
\section{Network protocol}
\section{\emph{hier moet een conslusie komen die de componenten aansluit op de requirements(?)}}
% TODO
%
%\section{Network protocol}
% TODO
% ZeroMQ gebruiken voor communicatie tussen meerdere processen (in
......@@ -503,6 +465,12 @@ events.
\chapter{Integration in VTK}
\section{The Visualization Toolkit}
\label{sec:vtk}
% TODO
% VTK heeft eigen pipeline, architectuur moet daarnaast draaien
% VTK interactor
%\chapter{Conclusions}
......@@ -526,6 +494,56 @@ events.
\bibliographystyle{plain}
\bibliography{report}{}
%\appendix
\appendix
\chapter{The TUIO protocol}
\label{app:tuio}
The TUIO protocol \cite{TUIO} defines a way to geometrically describe tangible
objects, such as fingers or objects on a multi-touch table. Object information
is sent to the TUIO UDP port (3333 by default).
For efficiency reasons, the TUIO protocol is encoded using the Open Sound
Control \cite[OSC]{OSC} format. An OSC server/client implementation is
available for Python: pyOSC \cite{pyOSC}.
A Python implementation of the TUIO protocol also exists: pyTUIO \cite{pyTUIO}.
However, the execution of an example script yields an error regarding Python's
built-in \texttt{socket} library. Therefore, the reference implementation uses
the pyOSC package to receive TUIO messages.
The two most important message types of the protocol are ALIVE and SET
messages. An ALIVE message contains the list of session id's that are currently
``active'', which in the case of multi-touch a table means that they are
touching the screen. A SET message provides geometric information of a session
id, such as position, velocity and acceleration.
Each session id represents an object. The only type of objects on the
multi-touch table are what the TUIO protocol calls ``2DCur'', which is a (x, y)
position on the screen.
ALIVE messages can be used to determine when an object touches and releases the
screen. For example, if a session id was in the previous message but not in the
current, The object it represents has been lifted from the screen.
SET provide information about movement. In the case of simple (x, y) positions,
only the movement vector of the position itself can be calculated. For more
complex objects such as fiducials, arguments like rotational position is also
included.
ALIVE and SET messages can be combined to create ``point down'', ``point move''
and ``point up'' events (as used by the \cite[.NET application]{win7touch}).
TUIO coordinates range from $0.0$ to $1.0$, with $(0.0, 0.0)$ being the left
top corner of the screen and $(1.0, 1.0)$ the right bottom corner. To focus
events within a window, a translation to window coordinates is required in the
client application, as stated by the online specification
\cite{TUIO_specification}:
\begin{quote}
In order to compute the X and Y coordinates for the 2D profiles a TUIO
tracker implementation needs to divide these values by the actual sensor
dimension, while a TUIO client implementation consequently can scale these
values back to the actual screen dimension.
\end{quote}
\end{document}
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