If you’re one of those audience members who sits through the credits on a Marvel film — and usually there’s every reason to, in order to catch the post-credits tag — you have noticed the largest “blocks” of credits that scroll up the screen: the visual effects artists.

VFX is, obviously, a huge component of the making of giant blockbusters. On Avengers: Infinity War, for example, only around 80 shots were untouched by the visual effects team, out of a total of more than 2,500 shots.

But who exactly are all these VFX artists, and what do they do? Because so few of them actually receive individual acknowledgment for their contributions, Twitter user DradakVFX tried to lift the lid on just who makes up the long list of effects credits in Avengers: Endgame by sifting through the credit block of artists and heads of departments for VFX studios Framestore, Industrial Light & Magic, and Cinesite, and color-coding each person into their respective roles, from jobs such as texturing and compositing to rotoscoping.

That helps you understand the breadth of work that goes into a movie like Endgame, but if you’re a casual moviegoer, the job descriptions may not mean much. It might seem obvious that VFX artists build creatures and characters in CG and place them into shots, but there’s so much more involved. Scenes are often crafted with stand-ins, or actors in motion capture suits or partial costumes, that then need to be replaced or painted out. All of this is incredibly painstaking VFX work.

It’s important to remember that different VFX studios have different names for certain positions, which may be one reason why the credits list so many people under the generic titles of “artists” or “digital artists.” Also, what ends up in the credits roll is often a matter of negotiation. Sometimes not all the VFX artists who work on a film are even listed, as there can be a maximum number allowed for each VFX studio.

Likewise, all the work involved in bringing visual effects to life tends to happen concurrently, so there’s not necessarily an “order” to these roles in the production of shots for a movie, and there are certainly other crucial visual effects roles that may not be touched on here. But based on DradakVFX’s breakdown, here’s what you need to know for the next time you’re reading through names in anticipation of one more MCU clip.

Rotoscoping/Prep

Need Robert Downey Jr.’s Tony Stark to appear as if he is fighting on the alien world Titan, as he did in Infinity War? All that starts with live-action photography, often against green screen or just a partial set. Rotoscope artists — regularly dubbed the true heroes of VFX for the meticulous work involved — then have to cut Downey Jr. out of the photography. This allows other things to be placed behind him, or for the actor to be properly integrated against digital environments or with CG characters.

Tracking/matchmove

Like rotoscoping, this is another role in the “prep” phase of visual effects, and it’s crucial for films with tons of CG imagery. What happens here is that a tracking or matchmove artist will track — often frame by frame — the motion of the camera or a live-action actor, vehicle, or prop so that it can match the motion of other CG elements. Without it, things can appear to incorrectly “float” in a scene (i.e., they don’t “track” to the motion of something else).

Modeler

All the CG characters, creatures, ships, environments, and even clothing in the Marvel films need to be created, or modeled. You can think of modelers just like sculptors or even set builders. CG modeling tends to happen in specialized 3D software, sometimes starting from scratch or from concept art, and sometimes with the aid of reference photography and 3D scans.

Rigging

Once a CG model is made, it will need to have motion, and that begins with the job of riggers. These artists provide an underlying digital skeleton to give CG characters the most realistic (or sometimes deliberately unrealistic) motion possible. They really get under the hood, and often need to have an intimate understanding of anatomy.

Animator

With a rigged CG model in their possession, animators take on the task of providing animation for CG characters, vehicles, or just about anything else that has to move. These artists might use on-set reference, motion capture, or even film itself in order to do so, or go with a completely “key-framing” approach. That means moving the model into key poses to form the final performance.

Texturing

Now we move to the surface of these CG models, such as the skin or clothing of a character, or a ship’s paint job. All these things need to be painted, which is the job of texture artists, who use digital brushes to do just that. Where do they get these textures from? Often from the real world, or from vast libraries of materials.

Grooming

Rocket simply isn’t Rocket, say, without his unique furry features. But simulating CG hair is still one of the hardest things to do in visual effects, so grooming artists work to both craft the look of the hair and work out how it should behave. In many cases, there are millions and millions of individual pieces of hair that need attention.

Creature FX

This is somewhat of a catch-all term for all the kinds of extra pieces of motion and simulation that can be added to a creature beyond modeling, texturing, and rigging. For example, underlying muscle and flesh simulations can add just the right kind of wobble and jiggle as Thanos walks or speaks. Hair, fur, and clothing simulations also come under this role.

FX

Explosions! Water! Superhero magic! This is the domain of FX artists, who replicate real-world phenomena or create other kinds of effects that need enormous amounts of particles or fluids. When Doctor Strange fires off his astral and mystical powers, they tend to come alive thanks to careful artist choreography of complex simulation software.

Environment/DMP

Before the days of digital visual effects, environments that couldn’t be filmed for real were often done as matte paintings: literally, paintings on glass. That name — matte painters — is still used to describe the role, with digital matte painting (DMP) covering what they now do with the aid of digital tools. No longer, however, are environments just 2D paintings; often, they’re complex 3D assets or extensions of live-action photography.

Lighting

Many of the roles in VFX are about asset creation, but once these assets move into real shots in the movie, they need to be “lit,” just like a cinematographer lights a set or an actor. Maybe Groot needs to appear in shadow, or in an overcast environment — lighters will dial in all the different scenarios. In visual effects, lighting also often goes hand in hand with rendering.

Compositing

Think back to the Tony-Stark-on-Titan example. The actor needs to be combined with a background environment, with his Iron Man suit, with other characters and assets, and with lasers, explosions, and all manner of other effects layers. These layers are put together by compositors, who are often involved toward the end of the process to form the final shots, where they also fine-tune lighting and extra effects elements. Seamless compositing can make a scene look like no visual effects are actually involved at all.

Pipeline TD

Just as these Marvel movies have become huge productions, so too have the pipelines employed by VFX studios to handle so many shots. A pipeline TD, or technical director, is charged with fitting together the different toolsets, code sets, communication links, and processes behind bringing VFX elements from almost nothing to their final form.

Editorial

There’s editing in VFX? There sure is. VFX editors are often the go-between for VFX studios and the main production, placing work-in-progress or completed scenes in context, moving footage through the facility and running shot reviews. They are also regularly the artists behind those killer visual effects breakdowns you see, especially during awards season.

Those are the main VFX roles highlighted by DradakVFX in his color-coded Endgame credit observations. Next time you’re enjoying the credits for one of these films, take a moment to think of the long hours these artists might have endured in bringing your favorite characters to the screen. It certainly takes an army.

Ian Failes is a journalist based in Sydney specializing in visual effects and animation. He recently launched his own VFX and animation publication called Befores & Afters. He also writes for Cartoon Brew, VFX Voice, 3D Artist and 3D World. Ian is the author of the book, Masters of FX. Find him on Twitter at @vfxblog.