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

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

Like this article? We recommend

Fire

Synthesizing fire from scratch remains an advanced topic within the upper reaches of visual effects research and development. I was employed at The Orphanage during its work on Hellboy, a story featuring a leading character whose preternatural gift is to create lots and lots of fire when upset. There was no way to use photographed fire for those shots because they required too much interaction with the rest of the scene. I was amazed at what the team responsible for these effects was able to pull off.

Within After Effects, fire synthesis is way too hot to handle. If fire is at all prominent in a shot, it will require elements that come from somewhere else—most likely, shot with a camera. Let's take a look at what's involved.

Creating and Using Fire Elements

Figure 16 shows fire elements filmed for effects usage. The big challenge when compositing fire is that it doesn't scale very realistically. You might think that any fire that you shoot with a camera will look better than something you create on a computer, but a fireplace fire looks like it came straight from your hearth, no matter how it's scaled or retimed.

The bigger the fire you need to shoot, however, the more expensive it's likely to be because you really need the fire to be shot in negative space—against a black background—so that you can composite it using Blending modes. Fire is obviously capable of illuminating the entire environment around it, so if that environment has specific detail, it can be all but impossible to isolate the fire from the environment.

Figure 16

Figure 16 Fire elements typically are shot in negative (black) space, or occasionally in a natural setting requiring more careful matting. By adjusting Input Black in Levels, you can control the amount of glow coming off the fire as it's blended via Add mode, lending the scene interactive lighting for free. (Images courtesy of Artbeats.)

This, then, is a case where it's worth investing in proper elements. In many cases, stock footage companies such as Artbeats have anticipated your needs. Whether you require burning half-height miniature trees or a flamethrower, you're sure to find solutions for a wide variety of shots in these stock collections. As a result, the scale and intensity may be more correct than what you can easily shoot on your own.

Hang Fire

When employing a fire element shot against black, it's best in 8 bpc mode to employ Screen or Add Blending modes (not a luma matte) to permit the background to be seen behind the fire. The Unmult plug-in from Knoll Light Factory will also effectively transform the black background into transparency. Neither of these methods by itself, however, is enough for a final composite (see Figure 17).

Figure 17

Figure 17 Using luma matte fire—for example, with Extract (top left)—will never look good. Add mode tends to appear oversaturated in 8 bpc mode (top right), while it and Screen (bottom left) both are initially more transparent than they should be. Unmult gets the transparency more correct by removing black pixels, but the result lacks contrast (bottom right). (Fire courtesy of Artbeats.)

If you simply lay the fire layer over the background and apply Screen mode, the effect may look rather weak. There are several ways to strengthen it, but this is a case where linear blending and Add mode are ultimately the best combination. To firm up a fire, flare, or other bright element, you could try this:

  1. Apply Unmult in addition to setting a Blending mode (Screen or Add).
  2. Fine-tune the result with a Levels effect, pushing in on Input White and Black (as well as color-matching overall).
  3. Overlap multiple occurrences of the fire element to create a raging inferno.

However, the more elegant solution is to switch your project to 32 bpc linear and use Add; the result is far more natural and less of a kludge. Additionally, as with fog elements, the "secret sauce" is a Compound Blur effect on the background, using the Luminance of the fire element (see Figure 18).

Figure 18

Figure 18 Add mode behaves more naturally with linear blending via 32 bpc mode (top left). To really sell the effect, however, requires the addition of a compound blur effect to the background (top right). The combination is immediately more believable (bottom).

Of course, a final composition will often involve multiple fire elements as well as smoke (see Figure 19). As always, things go better in linear floating-point.

Figure 19

Figure 19 The background plate was stock footage of a raging fire (left), but it wasn't raging quite enough. Layering extra raging inferno footage helped the opaque look of such intense fires to break through the overlaid extra layers of smoke (right, courtesy of ABC-TV).

Light Interaction

Provided that your camera isn't moving too much, a 2D fire layer should read adequately as being fully three-dimensional. If it's not looking believable in your scene, the problem is likely a lack of interactive light. As mentioned earlier, fire tends to illuminate everything around it with a warm, flickering glow.

There are a few ways to add this glow. First of all, as Figure 20 shows, your fire element may include a certain amount of glow that you can use. Raising Input Black when adjusting Levels tends to eliminate this glow, so that control is an effective way to dial the glow in and out.

Note, however, that fire glow isn't anything particularly unique or special; you can re-create it either via a heavily blurred duplicate of the source fire or by using a masked and heavily feathered orange solid, with perhaps a slight amount of wiggle added to the glow opacity to cause a bit of interactive flickering.

Figure 20

Figure 20 Depending on the Levels settings applied to the source fire element (specifically Input White and Black on the RGB and Red channels), you can end up with a lot of extra glow or omit the glow entirely.

Into the Third Dimension (and Beyond!)

You can pull off the illusion of fully three-dimensional fire, especially if the camera is moving around in 3D space, directly in After Effects. I was frankly surprised at how well this worked in the shot featured in Figure 21. The background plate is an aerial flyby of a forest. Because of the change in altitude and perspective, this shot clearly required 3D tracking. The keys to making this shot look fully dimensional were to break up the source fire elements into discrete chunks and then stagger those chunks in 3D space so that, as the plane rose above them, their relationship and parallax changed (see Figure 22).

Figure 21

Figure 21 Before-and-after sequential stills of a flyover shot. Because of the angle of the aerial camera, the shot required 3D motion tracking, originally done using http://www.2d3.com/product/?v=1". (Images courtesy of ABC-TV.)

Figure 22

Figure 22 A top view of the 3D motion-tracked camera from Figure 21 panning past one set of fires (of which the final composition had half a dozen). The pink layers contain fire elements, the gray layers smoke.

It's easy to get away with any individual fire element being 2D in this case. Because fire changes its shape constantly, there's nothing to give away its two-dimensionality. Borders of individual fire elements can overlap freely without being distracting, so it doesn't look cut out. The eye sees evidence of parallax between a couple dozen fire elements, and doesn't think to question that any individual one of them looks too flat. The smoke elements were handled in a similar way, organized along overlapping planes. Smoke's translucency aids in the illusion that overlapping smoke layers have dimensional depth.

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.

Overview


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.

Surveys

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.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email ask@peachpit.com.

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.

Security


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

Children


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

Marketing


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 customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


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: www.peachpit.com/u.aspx.

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 NevadaDesignatedRequest@pearson.com.

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.

Links


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