PresenterMouse LASER-Pointer Tracking System

PresenterMouse
LASER-Pointer Tracking System
Evgeny Popovich (I.D.: 319204103)
The Faculty of Computer Science – Technion I.I.T.
Joint work with Zachi Karni
Supervised by Prof. Craig Gotsman
Figure 1: The PresenterMouse system at work.
Abstract
We present a novel LASER-Pointer tracking system for use in interactive presentations. The LASER-Pointer’s red dot is meant to draw the audience’s attention to a specific place in a slide. Our system enables presenters to use the LASER-Pointer as they
would a regular mouse cursor. The system detects the red dot on the screen and
automatically brings the cursor to it. This feature paves the way for highly interactive
and dynamic presentations.
1. INTRODUCTION
Computer-based presentations are today the most common way to teach courses and
make scientific and business presentations. To support this, most university classrooms and business conference rooms are equipped with high-resolution projectors
and computers.
In order to control their presentations, presenters must use the computer keyboard and
mouse. Operations such as forwarding to the next slide or handling the presented application anchor presenters to their computers instead of permitting them to face and
address audiences. The development of cordless mice has given presenters some degree of freedom by allowing them to control presentations from a distance, yet they
are still required to place the mouse on a hard surface in order to use it.
LASER-Pointers are small gadgets that are able to generate a narrow red light beam
and project a red dot onto almost any surface. Presenters usually use them to draw the
audience’s attention to important issues on the screen. Logitech® Cordless-Presenter
combines a LASER-Pointer with a cordless mouse. Although using such a device en-
ables the presenter to control a simple presentation (going back and forward between
slides), it cannot be used for complex applications, for example: manipulating 3D objects in 3D viewers.
Our project enables the presenter to perform any mouse task using only the LASERPointer’s red beam and the mouse buttons, by moving the mouse cursor to the position
of the red LASER point.
This document is organized as follows: Section 2 lists the system components, Section
3 briefly describes the system algorithm, Section 4 describes the installation procedure, Section 5 describes the PresenterMouse daemon initialization and Section 6
briefly describes the puzzle application, which was developed to demonstrate the PresenterMouse system.
Figure 2: Zachi Karni is using the PresenterMouse system.
2. SYSTEM COMPONENTS
The PresenterMouse system includes the followings components:
Computer: It must run a Windows®1 operating system and host the presentation and
the PresenterMouse daemon application. The PresenterMouse daemon is optimized
and on Pentium III 1000Mhz processor, it uses less than 20% of the CPU time.
Projector: A wide-screen projector must be connected to the computer.
USB-Camera: A simple web-cam must be connected to the computer using a USB
interface. We used two web-cams: 3Com®HomeConnectTM and IBM UltraPort. Each
of them uses the USB 1.1 interface and can deliver up to five 320×240 True-Colors
images per second. Modern cameras use the USB 2.0 or FireWire interface. Such
cameras are able to deliver high-resolution images at high frame rates. Using such devices will enhance the PresenterMouse performance and will increase its accuracy.
LASER-Pointer: Any simple red-beam LASER-Pointer commonly used in presentations is suitable. However, we used the Logitech® Cordless-Presenter, which combines a LASER pointer together with a cordless mouse. This allowed us to use the
mouse buttons in order to control the presentation.
(a)
(b)
(c)
(d)
Figure 3: PresenterMouse components: (a) The complete system (b) the projector screen (c) Logitech® Cordless-Presenter (d) IBM ThinkPad T22 with the IBM UltraPort Camera
1
PresenterMouse was tested under Windows XP Pro, XP Home and 2000.
3. ALGORITHM
The heart of the PresenterMouse system is the LASER red dot recognition algorithm,
which is based on a high-pass filter. We consider only the red component of each
frame image. (We found out that although the LASER point is red, its center pixels
are usually captured as white (due to surface reflection and camera saturation)).
Each new frame image, I rt , is differentiated from a mean frame M rt , which is the
mean of the previous frames (we used ten previous frames):
Drt = I rt − M rt , M rt =
10
1
10
∑I
i =1
t −i
r
We consider the pixel with the highest value in Drt as the candidate for the new position of the LASER point. We found that when a LASER point exists, the highest value
in Drt locates it. However, even when there are no LASER points in the image the
highest value locates arbitrary points.
In order to distinguish between the two cases we set the mouse cursor to the candidate
position only if the following two conditions take place:
The difference between the highest value in Drt and the mean of the ten successive
highest values is higher than a threshold (the user specified sensitivity value):
D rt = sort − descending ( Drt )
11
D rt (1) − 101 ∑ D rt (i ) ≥ Threshold
i =2
The distance between the candidate point position and the previous LASER point position is smaller than 20 pixels.
After locating the LASER point in the captured image, it must be correlated to its position in the computer screen space. Since, usually, the image on the computer screen
fills only a portion of the captured images (the camera’s lens takes in more than the
computer screen), a registration-process must be preformed to correlate between the
two (as described in Section 5.4). In the Calibration stage, the user specifies the positions of the four corners of the computer screen in the captured image and the correlation is done using the following two equations:
u=
a⋅ x + b⋅ y + c
g ⋅ x + h ⋅ y +1
v=
d ⋅ x + e⋅ y + f
,
g ⋅ x + h⋅ y +1
where (x,y) is the LASER point in the captured image and (u,v) is the same point on
the computer screen. In order to find the constants a to f, the following linear equation
needs to be solved after the Calibration stage.












x0
x1
y0
y1
1
1
0
0
0
0
0
0
0
−W ⋅ x1
x2
x3
y2
y3
1
1
0
0
0
0
0
0
−W ⋅ x2
0
0
0
0
0
0
0
0
0
0
x0
x1
x2
y0
y1
y2
1
1
1
0
0
− H ⋅ x2
0
0
0
x3
y3
1
− H ⋅ x3
0  a  0 
−W ⋅ y1   b  W 
    
−W ⋅ y2   c  W 
    
0  d   0 
⋅
=
0  e  0 
    
0  f 0
− H ⋅ y2   g   H 
    
− H ⋅ y3   h   H 
where (xi,yi) i=0..3 are the calibration points the user specifies during this stage and
(W,H) are the computer screen’s resolution (width and height).
4. INSTALLATION
4.1.
Download
The PresenterMouse wizard and demo applications can be downloaded from then project web page: http://www.cs.technion.ac.il/~zachik/projects/presentermouse or from the
FTP site: ftp://ftp.cs.technion.ac.il/pub/misc/zachik/projects/PresenterMouse.exe.
4.2.
Unpack
After downloading PresenterMouse.exe, double click on the file and unpack its contents into a temporary folder of your choice.
4.3.
Install
After unpacking PresenterMouse, double click on the setup.exe file to start the Installation wizard. Follow the wizard instructions through to the end of the installation.
You can abort the installation by pressing Cancel during each of the wizard's stages.
4.3.1.
Welcome Stage
Greets new users.
4.3.2.
Select Installation Folder Stage
Select the folder in which to install the PresenterMouse wizard and the demo applications. You can also choose to make the the wizard and applications visible only to you
or enable all the computer users to see it.
4.3.3.
Confirm Installation Stage
This is the final stage before the installation. Selecting Next will start the installation.
Selecting Cancel will abort.
4.3.4.
Installation Complete Stage
The PresenterMouse wizard and applications were successfully installed. Selecting
Close will end the Installation wizard.
4.4.
Uninstall
Use Add and Remove Programs from the Control Panel to remove PresenterMouse
and its demo applications.
5. ACTIVATION
Once installed PresenterMouse can be activated by choosing the PresenterMouse application from the Start menu. The following screen will appear:
5.1.
Choosing and Setting the Camera
Pressing Next in the About page will take users to the camera selection and setting
page.
5.2.
Choosing the Camera
Clicking on Choose Camera will provide a list of all installed cameras in the computer. Choose the one you wish to use.
5.2.1.
Setting the Video Format and Properties
Each camera has its own Video Format and Video Properties wizards. Selecting one of
them will open the proper window. In most of our tests we used a 320x240 color image format with automatic camera gain control. It was our experience that using the
default camera parameters gave us acceptable results.
5.3.
Positioning the Camera
In order for PresenterMouse to work well, the camera needs to see the entire computer screen. To best position the camera, follow the stages listed on the Camera Position page.
5.4.
Calibration
In most cases the camera will display more than the computer screen. In order to improve PresenterMouse performance and to position the mouse correctly on the screen,
it is necessary to specify the screen boundary in the camera image. To do so, follow
the instruction on the Calibration page.
5.5.
Finalizing the Wizard
Pressing Start on the final wizard page will start the PresenterMouse application. Follow the instructions on this page to fine-tune PresenterMouse performance.
5.6.
Enabling and Disabling PresenterMouse
Ctrl+Shift+E and Ctrl+Shift+D can be used to enable and disable PresenterMouse
activities. It does not stop the application from running, but only causes the cursor
(temporarily) from moving to the new LASER point on screen.
5.7.
Setting the Sensitivity
After pressing Start on the final wizard page, an icon will be placed on the Task Bar.
Right-clicking on it will open the application menu. In order to set the proper sensitivity we recommend Enabling the application and testing it with a LASER-pointer. In
case it does not function properly (the LASER's red point is not recognized), Disable
the application, increase the sensitivity and Enable it again. Repeat these stages until
the application is working properly.
6. DEMO APPLICATIONS
The puzzle demo application will demonstrate the PresenterMouse system as it was
used together with the Logitech® Cordless Presenter. The application receives an image and partitions it into rectangular pieces (the user can choose the number of
pieces). The user is required to rearrange the pieces by dragging and dropping them
into their original place in the image.
Beside presentations and the puzzle demo application, PresenterMouse can be used to
handle any Windows®-based application. For example in the Virtue®Optimizer application, PresenterMouse can perform 3D object manipulations such as rotate, translate
and scale.