CLASS 3•
TECHNICAL OBJECTIVES • Page 2
Review Skill
2.3) Grabbing video on screen and grabbing a frame as a cast member
Lingo: on startmovie, on stopmovie, Cleanup(), global TrackObj,
ShowVideo(TrackObj,0,0), GrabToCast(TrackObj, Cast Member number)
Directions:
Before you begin this exercise please complete the following:
- Download the
Sample Movies folder ("All TrackThemColors Mac Samples") from the
www.smoothware.com site.
- Move TrackThemColorsDemo-Fat
XTRA into Macromedia Director XTRAS folder
- Connect Canon
GL-1 video camera to the MacG4 via a 4-6 pin firewire cable. Power on to Camera
Mode and do NOT insert a tape. Use the AC adapter for the camera. (Otherwise
camera will power off while you are trying to track movement and change).
- Open Director
8.5, choose File>Open and find "MacTrack Track A Color.dir" in
the samples folder.
- Choose Modify>Movie>Xtras
and click ADD. Scroll down and find TrackThemColors, select it, add it to
you list and save movie.
- Play with the
movie . Look at the scripts and try to get a sense of how it's working.
Skill 3.3)Tracking
one color using the FollowThisColorPoints() method
*NOTE: None
of the tracking methods work without calling InitVideo() first, and also you
must establish an instance of the xtra in the startMovie script.
The FollowThisColorPoints(TrackObj,
tolerance, size, red, green, blue) method takes seven arguments and it returns
a list with an x and y coordinate. These coordinates are not stage-specific,
rather they are specific to the size of the video. Weirdly, the list is returned
with y-value first and x-value second.
- TrackObj - The
instance number returned from New().
- tolerance -
A number between 0 and 765 defining how close does a pixel in the video have
to be in order to be considered a match. (the larger the number the more points
will be returned).
- Size - A number
defining how far can two points be from each other and still be considered
as one point (the larger the number the less points will be returned)
- red - An integer
between 0-255 defining the red value of the color to be tracked.
- green - An integer
between 0-255 defining the green value of the color to be tracked.
- blue - an integer
between 0-255 defining the blue value of the color to be tracked.
- The FollowThisColorPoints()
method returns a list containing two numbers for each point found. [Horizontal,
Vertical, Horizontal, Vertical...].
Horizontal. The horizontal location, in pixels, of the point . The value
of this number is between 0 and the width of the video source as defined in
the InitVideo() method.
Vertical. The vertical placement, in pixels, of the point . The value of
this number is between 0 and the height of the video source as defined in
the InitVideo() method.
Group Exercises:
Complete in groups of 2-3
NOTE: Probably
it's best to complete these exercises tracking ONE color.
- Create a movie
where a single sprite changes its opacity, or blend in response to the presence
of a the color you are tracking.
- Create a movie
where a sprite moves to follow a the color you are tracking. Turn trails on
once you get this working so you can create a "drawing" by following
that color. Try varying the color and shape of the sprite you are using to
"draw."
- More challenging:
Create an audience survey where a participant answers survey questions, yes
or no, true or false by doing something with their body or by holding up a
card of a particular color.
ART and TECH
LINKS: Video tracking and audience participation
Cinematrix
Camille
Utterbeck
Wolfgang
Muench
Jim Campbell, Experiments
in Touching Color, Ackland
exhibit, series
of stills from Ars Electronica
More multimedia
art than you can imagine-HERE