Coordinates and Object Position in Space
The location of an object in Motion can be described in these terms as well. The coordinate
system used by Motion specifies the center of the Canvas as 0, 0, 0. Moving an object to
the left subtracts from the X value, while moving to the right adds to the X value. Moving
an object up adds to the Y value, and moving an object down subtracts from the Y value.
Moving an object closer adds to the Z value, while moving further away subtracts from
the Z value. The main difference between a 2D scene and a 3D scene is that in a 3D scene,
you can change your point of view, so that moving an object up doesn’t always mean
increasing its Y Position value.
Note: In a new project, the Canvas is oriented with the Z axis pointing straight at you.
This orientation preserves the traditional two-dimensional orientation of the X and Y axes,
which span the default Canvas from left to right (X) and top to bottom (Y).
3D Conventions
There are a few conventions commonly used to discuss and display three-dimensional
environments.
• Object movement is along an axis.
• Object rotation is around an axis.
• Each axis is color-coded: X is red, Y is green, and Z is blue.
• Positive rotation is counterclockwise around an axis.
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Chapter 21
3D Compositing