Creating the Stairs - Unarmed Animset

Behind the Animation: The Making of the "Stairs - Unarmed" Animset

Ever notice how characters in games often struggle with stairs? They might float, skate, or clip right through them. It’s a small detail, but one that can instantly break a player's immersion. At Filmstorm, we saw this as a challenge we wanted to solve definitively.

That’s why we created the Stairs - Unarmed Animation Pack. But this isn't just another set of animations; it's a meticulously crafted solution born from high-end technology and expert artistry. Today, we want to take you behind the scenes and show you exactly how it was made.

Step 1: The Concept – Solving a Notorious Pain Point

Before we even powered on a computer, our goal was clear: create a set of stair animations that were not just visually appealing, but functionally perfect for game development. This meant three things:

1. No Foot Sliding: Every footstep had to be planted firmly and realistically.
2. Seamless Transitions: Getting on and off the stairs needed to feel as natural as the core movement.
3. Game-Ready: The final product had to be easy for developers to implement in Unreal Engine.

The only way to achieve this level of fidelity is with Root Motion. Instead of the character’s capsule component driving the movement, the animation itself dictates the character's position in the world. This was our guiding principle from day one.

Step 2: The Capture – Precision with Xsens Motion Capture

To get the natural, nuanced motion we were after, we turned to our Xsens MVN Link motion capture suit.

Unlike optical systems that rely on cameras tracking markers in a specific volume, Xsens uses a system of Inertial Measurement Units (IMUs). These small sensors are strapped directly to the actor, capturing every subtle rotation and movement of their body, regardless of where they are in the studio.

This freedom was crucial. We built a physical set of stairs with standard dimensions, allowing our motion capture actor to perform the actions authentically. We weren’t faking it on a flat surface; we were capturing real human locomotion on real stairs.

Our capture session was exhaustive. We recorded:

• Multiple Speeds: Casual walking, jogging, fast running, and slow, cautious sneaking.
• All Directions: Ascending, descending, and even walking up and down backwards.
• Transitions: The critical moments of starting at the bottom, stopping at the top, and turning around. We also captured strafing and unique movements like taking steps two at a time.

The Xsens suit captured the raw data with incredible precision—the subtle shift in balance as the actor leaned forward to climb, the slight absorption of impact when stepping down, and the natural sway of the torso.

Step 3: The Cleanup & Retargeting – The Digital Artistry in MotionBuilder

Raw mocap data is a fantastic starting point, but it's far from game-ready. This is where Autodesk MotionBuilder, the industry standard for mocap editing, comes in.

Our animation team meticulously worked through every single take in a multi-stage process:

1. Data Cleaning: First, we filtered out any jitter or noise from the raw data, although it's very minimum with XSENS recordings. We stabilized the motion, ensuring there were no pops or unnatural shakes. The most intensive part was eliminating any remaining foot-sliding at the source, manually keying feet to ensure they were locked to the stair surface during each plant.
2. Characterization & Retargeting: This is the magic of bringing the performance to a game character. We created a characterization profile for our actor's skeleton and another for the standard Unreal Engine Mannequin. MotionBuilder then uses these profiles to "retarget" the actor's performance onto the UE Mannequin's rig. This is a delicate process that requires careful tweaking to ensure the proportions and limb movements translate correctly without breaking.
3. Root Motion Authoring: This was the most critical technical step. We isolated the character's forward and vertical movement—the data that makes them travel up and across the stairs—and "baked" it into the root bone of the UE Mannequin's skeleton. The rest of the body animates in place relative to that root. When a developer enables "Root Motion" in Unreal Engine, the engine reads this data and moves the character's capsule component accordingly. The result? Perfect synchronization between animation and in-game position.
4. Polishing: Finally, we went back in with hand-keying to enhance the poses, clean up arcs, and ensure every motion was fluid and clear. We made sure the start and end poses for looping animations matched perfectly, and that transition animations (like stairs-enter-bottom-fast-up) would blend seamlessly with the corresponding loops.

Step 4: Final Implementation in Unreal Engine

With the animations polished and the root motion authored, we exported everything as FBX files and brought them into Unreal Engine 5. We tested each animation on the UE5 Mannequin in a test level, ensuring that the root motion behaved exactly as expected and that the character moved flawlessly up and down the digital stairs.

We also created the necessary Pose Matching assets. These are single-frame poses extracted from the animations that help the Animation Blueprint blend between different states (e.g., from flat-ground running to stair climbing) with absolute precision.

The Final Product

The result of this journey is the Stairs - Unarmed Animation Pack—a solution born from advanced technology and dedicated craftsmanship. By combining the physical performance from our Xsens capture with the digital precision of MotionBuilder, we've created a pack that we believe truly solves the problem of stair locomotion. It’s designed to save developers hours of frustration and elevate the quality of their projects.

We hope this look behind the curtain was insightful. We’re incredibly proud of this animset and can't wait to see how you use it to bring your worlds to life.

Ready to conquer stairs in your project? Get the Animset Today