Hotel Transylvania 2: VFX Supervisor Karl Herbst Discusses Animation Challenges and What Audiences Can Expect from the New Film


By: Haylee Fisher (@haylee_fisher)


Dracula is back for an all-new animated comedy adventure in Hotel Transylvania 2. The film follows Drac as he tries to keep daughter Mavis from leaving the hotel by bringing out the monster in her half-human/half-vampire son.


Director Genndy Tartakovsky doesn’t like to see the same thing twice. Because of that, animators ended up pushing the animation style, broadening the range of what is possible with animation software. Visual Effects Supervisor Karl Herbst led that charge, and in a recent interview with The Nerd Machine, discussed the challenges involved in making the movie, but also what made it so much fun.


Can you tell me about your personal involvement with Hotel Transylvania 2?


Sure. I was actually a [CG supervisor] on the first film and then when this film got started, it actually got started under the helm of the visual effects supervisor from the first film. His name is Daniel Kramer and I took over for Dan along the way because he moved on to a live-action film that he was really interested in working on. I became the visual effects supervisor, which means my job is to work with the creative team from Sony Pictures Animation, figuring out what the look of the movie was going to be and then developing a technical team behind me that will actually execute all the work and I’ll oversee all that work, all the way from models and rigs being created through final lighting and compositing and out to theaters.


When I told my 13-year-old cousin I was interviewing you, she and her brother were so excited. She actually had a question for you.


(Laughs) OK!


What was the hardest character to animate?


You know, all the characters are a little hard to animate! Genndy [Tartakovsky, the director]’s style is very, very pushed, and the animation supervision team under Alan Hawkins, they really ended up having to sculpt all the major poses for every character and that’s what makes it really difficult. Genndy doesn’t have a style where you’re seeing the same poses. So you have this character and this is a standard sort of expression for this character and for this particular emotion, [Genndy] pushes it every time he sees it. So in one case it can be something that we’ve seen before but in the next case, it’s something new and very pushed. What makes it hard is we can never develop a rig, the armature that moves the character around, to accommodate all the things that Genndy’s going to ask for. And so the net result is that the animators end up sculpting almost by hand, like they’re pushing clay around to get those poses and that movement to the next pose. Every major moment with a character that you see is work.


For those of us non-animators, when you say “pushed style,” what exactly does that mean?


There are a couple of different ways to do animation, especially in CG. There’s keeping a model. We’ve designed this character, its proportions are this or the arm lengths are always this long, say two feet. And his body, his trunk, is two feet long or whatever. Something like that. So those are the proportions of the character. A pushed style means that we never hold the proportions. We will stretch them and shrink them and grow them all over the place. An example in our movie is Drac’s head. You think of a human character, the skull is pretty thick, pretty straight. Well, Drac’s skull changes shape multiple times per shot and in many cases, [goes] into extreme poses. So we’re basically off-model. We don’t keep to any sort of skeleton shapes in the body. We throw that out the window and every shot, every pose, is designed on the fly so where the elbow joint would be in one shot, it’s in a different location in the next shot.


It seems like the style was even different than how the first film was created.


It’s pretty similar, but in this case, Genndy, on the first film and coming from a 2D background, didn’t know how far he could go. And he really wanted to push things on the first one as well, but we were learning, too, how to even do his style and computer animation. Again, coming from a drawing background, a lot of our conversations were like, “Why’d you draw it this way? Why can’t you do it that way?” And then with 3D, you have to live with some physics, or we try to live to some physics, and we would just find ways to make those two meet.


Yeah, I was wondering how the approach compared between the two films.


The approach was the same other than the fact that when we went through the first film, we learned a lot. So we went back to our development team and came up with some clever tricks on how to help get [Genndy’s] style. For animators who are doing performances, everything was basically the same other than the fact that Genndy does a lot of sketching over what we call our dailies. So the animator will do a first pass and we’ll show that to Genndy and then Genndy will actually sit there and draw on top of it frame-by-frame. “I really want to push this part of the pose or this part of the pose.” We added systems to take those line drawings and play them back for the animator while they’re in their software, which is Maya in this case, to be able to see those poses on the frame Genndy drew it on so they could try to match those silhouettes exactly. That was a new thing there. But down the pipeline, cloth simulation and hair simulation and rendering and lighting would push things as well. On the first one, [we learned] how to do motion blur. Genndy comes from that 2D background and so he likes that sharp, sort of leaning edge on top of something moving, and then all the smear behind it. In real photography, that’s not what would happen. Most lighting software and rendering software is designed around real physics so we actually ended up coming up with a new motion blur methodology that allowed us to what we called “bias” that, so we could keep that sharpness on the edge that Genndy liked, but we left it a little softer than normal and than what he wanted so it didn’t strobe across the screen, but that’s one of the things we ended up doing.


What lessons were learned on this film that you will be able to take to future projects?


(Laughs) Same things, really. The biggest obstacle we continue to have with this style of animation [is that it] doesn’t follow physics. A common phrase in reviews for this movie is about cloth simulation. This is what the cloth simulation could do and he was like, “That’s not right.” And you’re like, “Well that’s the way nature does it!” And he’s like, “No no no, you need to do this and that.” And if we could come up with what we call a solver for how to create simulations for cloth and hair that had his physics in mind, that would be the next step. I don’t know if we’re ever going to get there. What we do right now with [our cloth and hair technical directors] is that they have to understand his sensibilities and they actually simulate and tweak along the way. So they’ll do multiple simulations for one motion and then blend between those along the way. And actually they sometimes blend after the pose ends the animation. So it’s kind of collaborative between the animator and the cloth simulator and the cloth simulation team and trying to find those looks. We go back and forth with Genndy all the time. “Why’d you use that silhouette? Why’d you use that wrinkle?” And again, that’s not how physics works. So all the simulation software is based on physics and in this case, we had to break the rules where we could to try to get that particular look.


I was going to ask about the challenges involved, but it sounds like it was really that fight against physics.


It’s definitely the biggest challenge. Even with the motion blur stuff we did, we often ended up rendering the characters without motion blur and mixing parts of them back in to their motion blurred selves – the whole part of the pose. Some of the characters move so quickly pose to pose. Another example, again in the cloth simulation, is that Johnny would go from standing still to zipping over to another pose and when he would stop, his clothes would fall off his body in the simulation software. And people would ask, “What do I do here?” You have to deal with the frames and figure out how to blend in that moment. A lot of times with simulation software, it’s also the follow-through, meaning you view the movie from left to right, and when you stop on a dime going to the right, your hair would swing to the right a little bit and back to the left and then center. Genndy doesn’t like that at all. “When I stop a pose, I want to stop the pose.” So we’d have to find a way to still get a little bit of the subtlety, so it becomes a lot of artistry and hand-holding and all the stuff through the pipeline.


What do you hope audiences take away from the movie?


I really hope they see the beauty in it. This movie is definitely a step forward for us in terms of look-of-picture and a more realistic lighting style and also smooth blending of Genndy’s 2D past. I think it’s a really great blend of those two things and I hope they notice that. I think from a performance point of view, we definitely move things forward in terms of taking that pushed animation and showcasing it and also still showcasing simulation in terms of cloth sim and hair sim. There are a lot of cases in the first film where shots didn’t have simulation at all because we just couldn’t figure out how to provide it. In this case, we never let a shot go through without it. And I hope they really love the characters. Dennis is a really cute, lovable character who we had a lot of fun making. He’s really great. And Vlad is the character for us that really broke conventions as well with Genndy’s pushed style. We tend to not put a lot of texture detail in the faces, but here’s this old character who has liver spots and wrinkles and everything else, and we really had to find a way to make that work. And going from extreme poses where you would normally tear at the textures and make them stretch and to make that work together. So it was a lot of fun. I hope they enjoy these characters because they work.


And since Halloween is coming up, and I know it’s the favorite holiday for many of us, I have to know: who is your favorite movie monster?


I gotta say, I grew up during the era of Friday the 13th, so I’m gonna have to go with Jason.


I’m a classic Universal monster girl myself.


You are? Who is your favorite?


Probably Frankenstein.


He’s probably second for me. I don’t know if you can put this in movie monster terms, but one of the movies that got me into animation was The Nightmare Before Christmas. Jack Skellington was like, “Wow! That’s something I want to do!” So I’d put that one on there, too.


Hotel Transylvania 2 is in theaters now.

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