ARIEL DIGITIZE PROGRAM
Digitizing
is the first step for analysis after the recorded images have been captured and
stored on the hard disk of the computer.
The APAS 4 SCREEN DIGITIZING APPLICATION (DIGI4) software is a Windows based program for digitizing images to
be analyzed using the Ariel Performance
Analysis System (APAS).
Initially,
the video image is captured and stored in memory. This eliminates any further need for video apparatus. The image sequence is then retrieved from
computer memory and displayed, one image at a time, on the digitizing
monitor. The captured image can be
enhanced or altered in several ways.
These included Zooming the whole frame or a defined, isolated portion of
the view. Changing the size may help
the person digitizing to more accurately determine a particular joint which in
the standard view could not be identified.
Using
the video cursor, the location of each of the subject’s body joints is selected
and entered into the computer. As each
point is selected, it is displayed within the video image on the monitor. This assists the user to evaluate his
current joint selection with the perspective of the previously identified joint
center. Another useful feature is the
“rubber-band” effect. This situation
occurs when the previously selected joint in the current frame is “fixed” while
the next joint center is being located.
The computer connects the preceding joint center with the cursor. As the cursor is moved to establish the
joint center location, a line is created which moves according to the cursor
motion. This assist in digitizing since
the connection between the two points represents the segment between the two
joints.
Digitizing
can be performed in one of two modes, either Manual or Automatic. Manual
digitizing is performed under computer control and the digitizing of video
images is computer assisted. Under
manual control, user participation in the digitizing process provides an
opportunity for error checking and visual feedback which rarely slows the
digitizing process adversely. A trained
operator with a reasonable knowledge of anatomy and a consistent pattern of
digitizing can rapidly produce high-quality digitized images. Automatic
digitizing requires some sort of highly visible markers. These may be reflective markers, LED’s or
simply markers with a high contrast to the immediate background such as black
markers against a white background.
User input is minimal as the computer automatically tracks the markers
based on color, contrast, position, velocity and acceleration.
Full
3-Dimensional integration has also been incorporated. During the digitizing process, 3D stick figures and graphical
information can be displayed simultaneously.
Graphs and stick figure images are updated immediately as the sequence
is digitized.
The
file structure of the APAS also opens the possibility of sharing data with
other users. Since data records are
stored as a file on the hard disk, these files can be transmitted worldwide by
modem or through File Transfer Protocols (FTP) on the Internet for
collaborative purposes.
The
DIGI4 program presents many options and features to the user, however, they are
relatively easy to master once you understand the concepts behind them. This manual is arranged to teach you these
concepts in a logical order by showing you, in step-by-step fashion, how to use
DIGI4.
A
few of the new features you will see in DIGI4 version 1.0
1. Multiple
Screen Digitizing. Up to four
images can be displayed and digitized simultaneously.
2. Multimedia
Compatible Image files can be
displayed in *.AVI format utilizing Intel Indeo technology.
3. Real-Time
Video Capture. Video can be
captured directly from the video source at rates up to 30 frames per second.
4. Real-Time
3D Transformation. 3D data files
can be generated and displayed simultaneously with the digitizing process.
5. Software Support For Panning Camera. Software developed by Ariel Dynamics allows
for “Panning” cameras without additional hardware.
6. Image Enhancement.
Several image processing options have been added to filter and/or adjust
the AVI images.
7. Improved AutoDigitizing. User adjustable spot locator parameters have been added.
8. Zoom Windows.
Static and Dynamics Zoom Windows have been added for improved digitizing
capabilities.
9. APAS Tool Bar.
A toolbar has been added to allow the user to activate individual APAS
modules from within the main programs.
10. Software Support For 120/240 Hz Digital Camcorders. Software developed by Ariel Dynamics has
been added for the JVC 120/240 Hz digital video (DV) camcorders.
The
following table provides the basic guidelines for required hardware to provide
the best possible performance. Required
software includes Microsoft Windows 95/98/NT/ME/2000 or later and APAS2000
Revision 1.0 or later.
Image
Format Required
Hardware/Software
___________________________________________________________
*.PCL(*.PCX) No Additional Hardware
Required
*.AVI Video For
Windows Compliant Video Board
Appropriate
Software Compressor/Decompressor (CoDec) for reading AVI file
1. Double-click the DIGITIZE icon located in the APAS
System window group. The main
DIGITIZE menu will appear. You are now
ready to create a new digitizing Project or restore a previously created
Project.
Prior
to beginning the Digitizing process, you should familiarize yourself with the
screen layouts of the various digitizing menus. Many functions can be selected using the DIGITIZE Tool Bar or by selecting the appropriate command from the Pull-Down Menus.
THE APAS TOOL BAR
You
can activate any of the APAS software modules from within the current program
by selecting the icons located on the APAS tool bar. The tool bar is toggled on/off using the APAS Toolbar command in
the VIEW menu. A check mark in the left
column of the menu indicates that the toolbar is currently active. The toolbar can be re-located anywhere in
the main program window by dragging it with the mouse. The following program modules can be
activated by clicking the appropriate icon.
Icons are pictorial representations of programs, commands or
functions.
THE DIGI4 TOOL BAR
You
can activate many functions by selecting the icons located on the DIGITIZE
program tool bar. The tool bar is located
near the top of the window. Icons are
pictorial representations of commands or functions. You can access the following commands by clicking the appropriate
icon.
THE STATUS BAR
The
status bar provides useful information about the current status of the image
file. The status bar is located at the
bottom of the DIGI4 window. The far
left side of the status bar is divided into five separate fields; Sequence Name Field, Control/Data Point Field, Frame Lock Status Field, AutoDigitizing Status Field and the Current X/Y Position Field.
Sequence Name indicates the
name of the current sequence. A missing
sequence name indicates that the sequence has not been selected.
Control/Data
Points
indicates whether the current display shows sequence data points or the control
frame.
Image Lock
Status
indicates the current state of the Image Lock as specified in the Lock command
of the Images menu. When images are
locked, the advance/reverse command acts on all open view windows. If the images are unlocked, the
advance/reverse command affects only the active window.
AutoDigitizing
Status
indicates the current status of the AutoDigitizing option. When AutoDigitizing is active, the first
frames will display AutoD : LEARN. Afterwards, the AutoD : ON indicator will be visible. When AutoDigitizing in not active the AutoD : OFF will be displayed.
X/Y Cursor
Position
indicates the current X and Y cursor position on the color display.
VIEW WINDOW LAYOUT
When
a View Window is opened, additional windows will be displayed inside the DIGI4
main window. Up to four windows can be
opened simultaneously. The View Title will be displayed at the top
of each View Window. The View Window
title incorporates the *.1t filename along with the IMAGE file being used and
the View information string. The View
Window Status bar is divided into four fields and is located at the bottom of
each View Window. The first field
displays the digitized Image number
and the current Image number of the
file. For example, the Image #
designated as 100/150 would mean that there are 150 images up to the currently
displayed image while only 100 of the 150 images have been digitized. The second field displays the current
sequence Time. This number is calculated based on the FRAME
RATE value specified in the View Information menu. If a frame rate of 60 is used, each time the image is advanced
the Time field will be incremented by a value of 1/60 = 0.01667 seconds. The Next
Point field specifies which point should be digitized next for this
window. The order of the points is
determined by the Point Identification Table.
When all points have been digitized for the current image this field
will display the label COMPLETE. The Bright/Dark field is active only when
AutoDigitizing. This field indicates
whether the markers used for AutoDigitizing are Bright (against a dark background) or Dark (against a light background).
Each individual view can be independently set for Bright or Dark markers.
Scroll Bars located
immediately above the View Status bar and also at the right side of the View
Window allow the image to be scrolled left/right and up/down. The small arrow in the upper right corner of
the View Window can be used to expand the window to the full screen.
The
Digitizing phase of the analysis makes extensive use of the mouse. The arrow keys can be utilized for
“fine-tuning” the digitized point, however, most users rely solely on the
mouse. The APAS computer is supplied
with either a two or three button mouse.
There is a Left (L), Middle (M) and Right (R) button. Several
functions have been incorporated into the mouse buttons to simplify the
Digitizing process. These functions are
listed when you select the ? icon
from the DIGI4 Toolbar.
Left - Selects the
current position of the cursor as the digitized point location
Middle - Corrects
the last digitized point. When a joint
is Digitized incorrectly, the Middle mouse button can be used to correct the
point. The cursor will reverse one
joint for each time the Middle button is pressed.
Right - Moves cursor
to the “estimated” location of the next point to be digitized. Since this requires previous information to
“estimate” the point location, this function has no affect in the first frame
Ctrl-Left
[Drag & Drop] - Press the Control key and Left mouse button
simultaneously to Drag the point nearest to cursor to desired screen location
then release the mouse button. If you
desire to Abort the Drag/Drop feature, simply drag off the client area and
release the mouse button.
Shift-Left [
Redigitize]
- Pressing the Shift key and Left mouse button simultaneously will cause a
Dialog Box to appear selecting a joint.
After a joint is selected, if AutoDigitizing is active, the program will
perform an Initial Locate for the spot associated with the specified joint
starting at the cursor location of the mouse click. If AutoDigitizing is inactive, then the specified joint is
re-digitized at the cursor location of the click.
Double-Click
Right
- . When all the points for the current
frame have been digitized and the Status Bar indicates that the image is
Complete, the Right mouse button can be “double-clicked” to advance to the next
image.