Vanguard: Slow Motion Effect & Compositing

Introduction

My name is Josh Harrison. I'm originally from Houston, Texas, and am currently finishing up the VFX program at Gnomon here in Hollywood. My background is mainly in architecture. I did an undergraduate degree at Cornell before heading out to California for work. I had it in my mind to transition to film and VFX eventually. While I always found architecture interesting, I never felt passionate about it during school or work. It was during my thesis project, where I did a traditional 2D animation as opposed to a conventional architectural project, that I decided to pursue animation and VFX as a career. It was a eureka-like moment for me when I realized how fun and exciting work could be.

At Gnomon

Going to Gnomon has been one of the most rewarding artistic experiences I've ever had. They have really streamlined their curriculum for the 2-year program. While classes cover a huge range of topics, the skills they cultivate largely build on one another and the overall pacing of the material keeps you on your feet. At times it feels like it's sink-or-swim, but there's also a strong support system, as teachers and other students are always eager to help you and collaborate. On that note, I also think one of Gnomon's strongest features is that the professors are either working professionals or have immense professional experience. It gives you a lot of confidence as a student knowing you're learning current practices, software, and pipelines. I genuinely feel that I'm getting prepared not only for my first job but also how the industry will change over the years. Gnomon actively trains its students to be self-sufficient and well-rounded. They want their alumni to be set up for the long run.

Vanguard project

I had a lot of fun with Vanguard. It started as the final project for my Dynamics class, which focused on fluid simulations, but I eventually combined it with my Houdini class, where we created our own custom RBD solver. Originally, the main character was supposed to throw a 'black-hole' grenade that would activate once hitting the tank, causing it to violently implode. For the assignment, we had to pitch an idea for a fluid effect to our teacher, David Stripinis. Unfortunately, in the end, I had to cut it in order to make the Best of Term contest deadline. I didn't want to rush the effect. It's something that I could've spent a whole term on by itself. I wanted to do it justice and might revisit it later.

Working in Houdini

Houdini is an incredibly robust program. It gives you so much power as an effects artist. Our teacher, Peter Claes, does such a fantastic job spoon-feeding complicated systems to us. During the term, we covered several of his RBD and liquid explosion setups, which I tried to customize and integrate into this scene. While all of the effects were done in Houdini, in terms of proceduralism, the tree explosion took the most finessing. I went through multiple iterations of varying tree geo, constraint systems, collision geo, fracture shapes, custom forces, etc before I landed on an approach that yielded the result I wanted. Often it would look fine during the sim but wouldn't visually match the pace or angle of the scene, so being able to change several parameters in earlier nodes and have it all update automatically was a godsend. Just knowing I always had the availability to return to any part of the setup allowed me to focus on creating wedges that conformed to my aesthetic.

Slow Motion

The slo-mo with the tree explosion was inspired by the forest scene in 'Sherlock Holmes 2: A Game of Shadows'. It's always been one of my favorite scenes and franchises. The way they integrated slow motion into their otherwise fast-paced, dynamic scenes was masterfully done, and I wanted to try my hand at it. One of the issues I ran into was with managing the collision geometry and the shape of the crater. I knew that a bullet or laser was going to be the driver of the effect, but introducing collision geometry did more harm than good, as the collider would push the fractured pieces into one another, causing them to intersect and creating unwanted artifacts and jittering. As I wanted the laser to leave a crater rather than cleaving the tree in two, I had to find a way to avoid sandwiching the geo in between the passive parts of the tree from one end and the bullet collider hitting it from the other. Dealing with wood splinters was also tricky because their teeth-like shape would sometimes trap interior ones causing fragments to bounce around locally or shimmy in one place.

My solution was to have a force explode it first from the interior, pushing all the pieces away from one another and giving them some breathing room, and then having a second force/collider push the pieces in the direction of the laser. The whole effect was simulated at a tenth of real speed too because I needed to anticipate the time warp. In the end, it took so much time for all the pieces to get momentum and form the plume shape I desired that I had to fix the impact moment in comp, otherwise the laser would pass through and it would take a second or two before the tree reacted.

Help from Megascans

I got a Megascans subscription a year back, and I couldn't be happier. As an FX Artist, it's luxurious to be able to get photo-real assets and propagate them into your scene, allowing you to focus on the actual animation and effects. For this project, all the rocks and trees (minus the ones I blew up) were from Megascans. Because the scene was set in a forest I used a fair amount of their woodland flora. Though they don't have many full tree options, with leaves and everything from root to stem, so I had to make do with their trunk assets. It's funny, because initially when I was incorporating camera shake into the scene, there were moments where you would notice I was almost only using incomplete tree trunks. So before I rescaled them, it was as if the firefight was occurring in a forest where all the trees were cut in half just above head height.

Lighting

Lighting was actually one of the trickiest aspects of this project. I knew from the get-go that I wanted the lasers to spice up the atmosphere of the piece. Having all these bright, neon lights whiz by really would add to the overall theme of chaos and brutality. Each laser is actually a single fire sim that was instanced multiple times all over. You don't notice it as much with motion blur, but during the time-warped moments, you can definitely see the individual lasers oscillate and distort. It wasn't feasible to drive the lighting solely by the emission property of the fluid, so I ended up attaching two different cylinder lights to each laser as well. One, affected meshes in the immediate vicinity, creating strong, harsh reflections on the characters and assets. The other was a softer light with a larger decay reach, which was intended to actually light the scene.

Comp

I'm a huge fan of fixing things in comp. It's been ingrained into me by my teachers here that a VFX artist should get to the rendering stage as early as possible because until you see the actual image/composition, you don't know exactly where you should spend your time or what aspects you can ignore. There's a decent amount of stock footage overlayed in the scene to help spice it up. All the dust motes, sparks, and explosion embers are from free stock footage that I've found online. Most of the gun flares were also free, green-screened images, although I did go back and add lights in the scene so that the muzzle flares also lit up the environment and affected the reflections of the scene. It's these final, polishing steps that really add to the cohesiveness of the scene in my opinion. When having a complex scene with multiple, separate elements, it's important to have them interact with one other as much as possible. It's crucial for grounding them in the same world and making CG animation credible and vivid.

Josh Harrison, Gnomon student

Interview conducted by Kirill Tokarev