The coordinate system Autograph uses differs from those found in other compositing software that generally define the origin of the coordinate system at the top left or bottom left of the composition. Autograph uses the system that every school in the world uses when teaching geometry on a 2D plane:
- The origin of the coordinate system (0,0) is always at the center of the composition. The composition size in pixels is defined by the composition Format.
- Defining an element’s position in this coordinate system is done through two parameters:
- The horizontal position (defined by the letter x)
- The vertical position (defined by the letter y)
- Values to the right and above the origin will be positive on x and y
- Values to the left and below the origin will be negative on x and y
- Autograph's coordinate system uses Pixels as units.
Advantages of this coordinate system
There are many advantages to having the origin of the coordinate system at the center of the composition:
- No matter the composition definition (FullHD, QHD, 4K) or ratio (16:9, 4:3, square, 9:16), the elements positioned at (0,0) will always be at the center of the composition. This is a huge advantage for easily generating multi-format videos.
- To replace a layer in the center of the composition after having moved it, you can just reset the position values to (0,0).
- Using expressions and placing/displacing another graphic element is done simply, avoiding additional calculations to find the center of the composition.
- When using both 2D and 3D elements in the same composition, the original coordinate system is identical in both dimensions. (0,0) is always considered the center.
- When animating two elements that are mirrored in relation to the center of the screen like two logos when two sports teams face each other in a match for example, simply animate the position of one of the logos, then use the same Position values for the other logo, multiplying them by (-1).
In Autograph, compositions have an infinite size by default. Graphic elements can be placed anywhere in compositions, even outside of the composition format. Using a coordinate system with an origin in the center allows you to change formats at any time without having to reposition graphic elements according to the new format. If the format is larger, layers will have more surrounding space. If it’s smaller, layers will be cropped by the format border. In any case, their position in relation to the center will remain unchanged.
After Effects defines the origin of its coordinate system at the top left of the composition. This derives from the way CRT screens used to work by drawing an image from the upper left corner.
Nuke defines the origin of its coordinate system at the bottom left of the screen.