|The Image Warper|
|Navigation Toolbar||The Image Warper is a Windows that supports
exploratory learning and enjoyable activities involving geometric transformations
and image distortion. The mathematics involved in the activity is richer
and more complicated than that of the Pixel Calculator. At the same time,
the mathematics is somewhat more hidden from the student, and needs to
be brought out through structured activities and teacher-initiated discussions
about translation, rotation, axis stretching, and invertibility of transformations.
The Image Warper uses a transformation method developed by programmers at Pacific Data Images, Inc. (as reported in the SIGGRAPH'92 Conference Proceedings), and used to produce a well-known Michael Jackson video that includes "morphing" sequences. This algorithm permits user specification of geometric transformations by drawing a set of line segments and moving them to indicate desired changes to particular parts of the image.
Simple transformations such as rotation, translation or scaling can be specified with single line segmentss. Users can create more complicated transformations by using two or more control segments at a time. Students quickly realize that each control segment has a global effect, but that "anchor lines" can help to limit that effect.
To see what the program is like, check out this picture of the Image Warper user interface. The interface includes a status bar which displays the current location of the cursor, as well as the location, length and angle of the last selected control line. This information can be used in activities designed to teach coordinate systems, angles, and geometry.
Last modified: Monday, 19 May 1997.