INTRO. Understanding the Photodex rotation system is very useful. It means you can choose a rotation direction without a lot of trial and error. Earlier versions of ProShow have always included the Rotate function. It has always represented rotation around the Z-Axis, the one axis we could never use. Since ProShow is a two dimension (2D) program, Photodex had invent a way to simulate a three-dimension (3D) environment. Their answer to that challenge was Tilt, rotation simulation about the X (Tilt-Vertical) and Y (Tilt-Horizontal) axes.
3D Simulation. Tilt simulates a 3D environment by the clever manipulation of a layers’ two sets of outside edges (i.e., top and bottom sides and/or the left and right sides). If the distance is increased between one side’s two opposing corners and decreased between the opposite sides two opposing corners, movement into and out of the screen is simulated (along the Z-axis). This size contrast of opposing layer sides tricks the brain into seeing a third dimension. That’s because the wider side “appears” closer than the narrower side.
ROTATION DIRECTION. When it comes to determining the rotation direction about an axis, which direction is associated with positive or negative values (as represented in the associated rotation box for Tilt-Horizontal, Tilt-Vertical, or Rotate)? The answer is fairly simple but requires a little explanation. To start with, a rotation around an axis is
- Positive, if rotation is clockwise (to the right),
- Negative, if rotation is counterclockwise (to the left; also known as anti-clockwise)
An easy way to remember it is to use the Left Hand rule. If you curl the fingers of your left hand and point the thumb pointing toward your face, you will note that the fingers curl in a clockwise direction.
DETERMINING ROTATION DIRECTION
All axes derive from a central point called the “origin.” All axes meet there. Let us assume that the thumb points along the axis in which you are interested. A positive axis direction for the
- X axis is LEFT,
- Y axis is UP, and
- Z axis is OUT of the screen (directly toward you)
So, for positive rotation values, if you point your left thumb
- UP, the curl of the fingers indicate that the layer will rotate to the left (Tilt-Horizontal)
- LEFT, the curl of the fingers indicate that the layer will rotate down (Tilt-Vertical)
- OUT (toward your face), the curl of the fingers indicate that the layer will rotate to the right (Rotate).
The following graphic might help:
TECHNICAL NOTE: Normally, a positive axis is to the right for X, up for Y, and OUT for Z. The representation of these axes might be a little different depending on your application. However, the relative orientation between each axis will remain the same. Photodex experienced a little faux pax that wasn’t discovered until it was too late to change. That’s why the X axis is giving clockwise (positive) rotations on a negative value axis. No big deal as long as things are consistent. But, still good to know.
TILT ORDER CONSIDERATION:
Here’s another helpful hint when dealing with rotations. If you want to know a layer’s correct orientation for a given set of rotations, consider each rotation type in the following order:
Or the following order:
Never start out with Tilt-Vertical … it will throw you off every time!
© 2012 Fenimore’s PhotoVideo Productions LLC