when applying position 0,0 to center the object in the middle of the frame, it moves to the very top lefthand corner.
after effects uses a pixel based coordinate system which most CG software use where the origin [0,0] is at the top left.
if you have applied [0,0] to the position and your shape is now way up left, this probably means you have changed the transform position to [0,0]. instead of the shape group's position or parametric path's position. transform position is relative to the composition that contains it. shape's group's position is relative to the layer that contains it.
shape layer's position can be confusing because you can find yourself managing different positions all in the same layer.
so if you want you shape to be in the center you need to make sure your path is centered in a group that is centered in a layer that is centered in a composition . a good practice is that first focus on modifying the shape's group's position, and later modify the position transform of the layer.
Let's see what we have in the first screenshot (the names you have could be different). we have 3 position parameters (there could be more):
- Rectangle Path 1* - parametric path position is your path's position in relation to the shape group that contains it. it will always default at [0,0] which is the center.
- Transform: Rectangle 1 - shape group position is your shape group's position in relation to the layer that contains it. it will be where you dragged your path in relation to the layer that contains it. so if you drew to the side of the layer - it will have certain values offset, and if you drew to the center - it will be close to [0,0] which is the center.
- Transform - this position is the layer's position in relation to the composition that contains it. the dimension of a composition and a layer are from the top left corner. so [0,0] is at the top left - add a ruler (ctrl+r) and see for yourself.
* if you drew you shape with the pen tool or imported an Ai file and converted to shape then the pen path shape will not have a parametric path's position but only a shape group's position that will default at [0,0]. you should then move on to centering your position and anchor point of the layer (not by setting them to [0.0]) but through a shortcut that's available later in this post.)
Here are ways to center your shape in the middle of the screen:
1. if you created a parametric shape (not with the pen tool) you can press UU to reveal all modified properties and reset your transform:shape position by right clicking and reset:
2. if you created a shape using the pen tool you already have a [0,0] in the position for the group so to center your shape you should center the anchor point and position for the layer by using the shortcuts one after the other:
Ctrl+Alt+Home - center anchor point
Ctrl+Home - center in composition