Publishers of technology books, eBooks, and videos for creative people

Home > Articles > Digital Audio, Video > Adobe After Effects

Keyframe Interpolation in Adobe After Effects CS4

This chapter explains how you can assign various interpolation methods to keyframes to impart nuance and variation to your animations using the Timeline panel’s Graph Editor. You’ll not only learn to decipher how After Effects depicts the ineffable qualities of motion, speed, and acceleration, but you’ll also see how it harnesses them. In the process, you’ll begin to realize that there’s a big difference between animating something and bringing it to life.
Like this article? We recommend

In Chapter 7, “Properties and Keyframes,” you learned to animate layer properties over time by setting keyframes. By defining only the most important, or key, frames, you assume the role of head animator. After Effects fills the role of assistant animator, providing all the in-between frames, or tweens, using what’s known as an interpolation method to determine their values.

Fortunately, you can instruct your assistant to use a range of interpolation methods. Some methods create steady changes from one keyframe to the next; others vary the rate of change. Movement can take a direct path or a curved route; an action can glide in for a soft landing or blast off in a burst of speed.

Without a choice of interpolation methods, your loyal assistant’s abilities would be severely limited. If animated values always proceeded directly and mechanically from one keyframe to another, all but the most basic animations would seem lifeless and robotic. To create a curved movement would require so many keyframes you’d begin to wonder why you had an assistant at all. Calculating acceleration or deceleration in speed would present an even thornier problem.

This chapter explains how you can assign various interpolation methods to keyframes to impart nuance and variation to your animations using the Timeline panel’s Graph Editor. You’ll not only learn to decipher how After Effects depicts the ineffable qualities of motion, speed, and acceleration, but you’ll also see how it harnesses them. In the process, you’ll begin to realize that there’s a big difference between animating something and bringing it to life.

Understanding Interpolation

The beauty of keyframes is that they save you work. If you set keyframes, After Effects calculates the values for the frames in between, a process known as interpolation. But to truly control animation, you’ll need some power over the interpolated values as well. You can gain this control—without significantly increasing your work—by taking advantage of a type of calculation known as a Bézier curve.

As you’ll see, mask and shape paths, spatial interpolation, and temporal interpolation are just different manifestations of the same Bézier principles. In fact, the ability to copy a mask path to a motion path attests to their shared Bézier heritage (see the sidebar, “Bézier Curves and the Motion Path,” later in this chapter). And as you’ll see in the following sections, most interpolation types (many of which include “Bézier in their names), calculate values in terms of both space and time: in other words, spatially and temporally.

Spatial interpolation

Spatial interpolation refers to how After Effects calculates changes in position, how a layer or its anchor point moves in the space of the composition. Does it proceed directly from one keyframe to the next, or does it take a curved route (Figures 9.1 and 9.2)?

Figure 9.1 Interpolation refers to how After Effects calculates a property’s values between keyframed values. Spatial interpolation determines whether movement proceeds directly from one keyframe to the next...

Figure 9.2 ...or takes a more curved, indirect route.

As you’ve seen, spatial interpolation is represented as a motion path—a dotted line connecting keyframes. Changes in a layer’s position value appear as a motion path in the Composition panel; changes in a layer’s anchor-point value appear in its Layer panel. Effect point paths can appear in both panels. So far, you’ve learned how to set a layer’s position at a keyframe by dragging in the appropriate panel; in this chapter, you’ll learn how to adjust the path between keyframes, or the interpolated values.

Temporal interpolation

Temporal interpolation refers to any property value’s rate of change between keyframes. Does the value change at a constant rate from one keyframe to the next, or does it accelerate or decelerate?

For example, Figure 9.3 shows two rabbits. They both travel the same distance in the same amount of time. However, one proceeds from the first keyframe to the last at a constant rate. The other gradually accelerates, starting slowly and then speeding up. As a result, the second rabbit falls behind at first and then gradually catches up. Both reach their destination simultaneously.

Figure 9.3 Both rabbits have the same keyframes, but they have different interpolation methods.

So far, you’ve viewed keyframes by expanding a layer’s property values in the Timeline. The keyframes’ relative timing and values give you some control of the overall speed of changes. But to see and manipulate the values between keyframes—the interpolated values—you must toggle the view under the time ruler to the Graph Editor. The Graph Editor represents the temporal interpolation as graphs that reflect a property’s rate of change and also lets you control it (Figure 9.4).

Figure 9.4 By toggling the Timeline panel to show the Graph Editor, you can see temporal interpolation represented as a graph. The straight line represents the top rabbit’s speed; the curved line represents the bottom rabbit’s speed.

Incoming and outgoing interpolation

Although interpolation refers to values between keyframes, it’s important to understand that you assign an interpolation type to keyframes themselves. The interpolation type, in turn, determines how values are calculated before the keyframe and after the keyframe—the incoming and outgoing interpolation. Therefore, the values between any two keyframes (the interpolated values) are determined by the first keyframe’s outgoing interpolation type and the next keyframe’s incoming interpolation type. The concept is most easily understood in spatial terms. A motion path consists of at least two keyframes. A tangent extending from the first keyframe determines the outgoing interpolation, while a tangent extending from the second keyframe determines the incoming interpolation. The motion path between keyframes results from their relative positions, as well as the length and angles of their tangents (Figure 9.5).

Figure 9.5 In a motion path, keyframe tangents define the outgoing and incoming interpolation and, hence, the curve of the motion path.

Temporal interpolation also affects a property value’s rate of change before and after the keyframe. In a speed or value graph, ease handles work a lot like tangents in a motion path. But because the graph lines don’t trace a spatial path, they can be a little more difficult to understand and adjust (Figure 9.6).

Figure 9.6 A value graph’s direction lines and a speed graph’s ease handles (shown here) define the incoming and outgoing interpolation. Here, the rate of change gradually accelerates after the first keyframe and then decelerates into the second keyframe.

Peachpit Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Peachpit and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Peachpit products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive:

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020