Adobe After Effects Basics Tutorial – Parenting

Parenting in Adobe After Effects

In today’s tutorial we will take a closer look at another very important basic technique available in Adobe After Effects: parenting. Parenting is used to link one or more layers to a single parent layer. Moving, scaling or rotating the parent layer will then automatically affect all of its children.

Parenting allows you to easily control a number of layer by linking them to a common parent. This is very useful for motion tracking and for managing more complex visual effects.

Let’s start by creating a simple rotating star! Start with an empty composition and then, with the star mask tool, simply drag in the centre of the preview window to create a new shape layer containing a star shape. I’ve set mine to use a red fill colour with a white outline and called the layer ‘Large Star’.

Open up the layer settings and alt-click on the stopwatch icon for the Rotation property. This will open up the After Effects Expression editor. In the editor, enter

time * 30

This will cause the star to continuously rotate around its anchor point.

Now create a second star, smaller than the central one and off to the side. Give it any colour you like and call it ‘Small Star’.

Let’s parent these two layers together. In the layer properties window you will find a column called ‘Parent’. Press F4 on your keyboard if you cannot see this column; it might just be hidden.

To parent the small star to the large star, drag the pick whip icon from the small star layer onto the name for the Large Star layer.

Alternatively you can select the Large Star layer from the parent dropdown menu on the Small Star layer.

If you scrub through your composition now, you will see that the little star is ‘pulled along’ as the large star rotates. This is happening because the Small Star layer is a child of the Large Star layer so the rotation to the parent is also applied to the child.

Now that we’ve got a hang of the basics, let’s move on to a few more complex examples!

Advanced Parenting in Adobe After Effects

Create a few more little stars and lay them out around the central, big star. Select all the small star layers and then select the Large Star as the parent from the dropdown menu. Note that you can bulk assign or unassign parent layers.

You can even bulk assign using the pick whip icon. Just make sure all the child layers are selected and drag from a pick whip icon for any of the children to the target parent layer’s name.

Play back your animation and you should see all the little stars spin around the central star.

Let’s get a bit more complicated. I’ve set up a number of stars to build me a little galaxy. The two red stars to the side rotate around the one in the center and the blue small stars rotate around their respective parent.

Playing this back you will get all of the stars rotating nicely around their respective parent. You can create some pretty awesome effects just using parenting and some clever animations.

Parenting and 3D in Adobe After Effects

There is an important thing to watch out for and that is when using parenting in combination with 3D. Set up a little galaxy again, but this time, line up all your small stars below the big red central one. Turn all of the stars into 3D layers and lay them out in a circle around the large star in 3D space. Be sure to use the top down view to arrange them correctly.

If you now rotate the large star around its y-axis you will see that all of the little stars are following along nicely in 3D space. They are rotating in a nice circle around the center.

If you decided to pre-composed your little stars into a separate composition and then parented that to the central star, this rotation would look rather different. The composition with the little stars would rotate around the parent, but the stars themselves would remain flat because they are simply part of that composition.

You can work around this problem by enabling the Collapse Transformations switch on the composition containing your individual layers. This will transfer the 3D information from the nested composition into the current one and all the stars will rotate around the central star as they did before.

You may wonder what all these examples have to do with creating real visual effects. Let me show you a real world application for parenting when trying to set a farm on fire!

Real World Application for Parenting in Adobe After Effects

Parenting is not just used to create spinning galaxies. It is extremely useful, especially when combined with motion tracking and Null objects. When you track a moving shot, you will usually end up with a few animated null objects that follow some visual elements in your scene. In the example below I tracked the telephone pole throughout the movement of the shot.

If you wanted to add some other visual element into the scene, say we wanted to set the fields on fire, you can use parenting to make sure the fire follows the camera’s movement correctly.

First, add the fire element into your scene. You can find free stock footage of fire at detonationfilms.com or and footagecrate.com also has some free fire elements. Once you’re done, parent the fire element to the Null object.

This will cause all transformations on the Null object to also be applied to the fire element and since the Null object is animated to follow the camera’s movement, the same now happens with the fire.

I hope this tutorial has shown you a few of the great things that you can do with parenting and is giving a feeling for how powerful this simple technique really is. You will use it very extensively when you start working with more complex visual effects.