How to Model a Realistic Bike Based on a 2013 Harley Davidson Sportster

Introduction

Hey everyone, it's good to be back! My name is Alexa Ranzola, and I'm a Freelance 3D Character Artist based in the United States. I specialize in creating distinct characters and props with a stylized to realistic aesthetic.

Since my last interview with 80 Level, I've been spending time experimenting with new tools and expanding my skill set. Along the way, I've taken on a few small commissions which have kept me creatively active while I continue to work on more ambitious personal projects like this one.

Viper Cruiser

I'm no stranger to hard surface modeling, but with the Viper Cruiser, I wanted to show how much personality can be infused into a mechanical, inanimate object. During the concept phase, I kept asking myself questions like, What environments does this bike travel through based on its dust and grime? What do the stickers and decals tell the viewer about the person who rides it?

Framing it in this way is especially important for character artists, as it helps reinforce intent and direction when working on non-character assets. This project is the first half of a series. The second part will reveal the mysterious biker that the project hints at!

The bike is based on a 2013 Harley-Davidson Sportster Iron, so I took the time to gather references from multiple angles to ensure accuracy. The goal was highly detailed and realistic, so I focused on matching real-world proportions, particularly when incorporating custom parts that I wanted to change from the base reference.

To stay organized, I first broke the bike down into its most distinct parts and worked my way from there. There are a lot of small components and wiring tucked within the body, so I focused on highlighting the most noticeable details while either cutting or baking the less prominent ones.

Modeling

Throughout the modeling process, I aimed to push the level of detail while maintaining a balance between visual fidelity and optimization. In the end, the poly count for the retopology clocked in at a sweet spot of 62k triangles, with each core piece of the bike cleanly separated and ready for rigging/animation. 

I used Maya for the bulk of the blockout and modeling, but for more complex shapes (like the speedometer and primary cover), I opted for ZBrush's powerful live boolean tools.

For the texturing phase, I focused on maintaining a non-destructive workflow that kept each core texture (metal, plastic, leather, etc.) separate using masks and material IDs. I started by creating a "control" version of the bike with less wear, no decals, and a gray clear coat. Since it is a game asset that the player could ride or display, it should be easily customizable, and an organized file is a necessity for iterations.  

Once my base textures were in a solid place, I began introducing the storytelling elements, spending most of my time refining the metal surfaces. I wanted a finish that wasn't overly clean or shiny but also not so dirty that it felt neglected. The most important factor of this entire process is preserving a very high-quality Roughness Map.

Details and Lighting

A lot of the bike's personality comes from the smaller details like the buttons, decals, and stickers. I made all of these textures either directly in Substance 3D Painter or in Photoshop. By keeping my UVs and textures tightly packed, I was able to consolidate everything into 1 material instance when transferring the textures to Unreal Engine, which kept the asset efficient.

I used a studio-style lighting setup in Unreal Engine 5 with hardware ray tracing, focusing on a clear presentation that didn't distract from the bike itself. To help the Viper Cruiser stand out, I chose a sharp orange background that contrasts nicely with the green coat of the bike.

Rather than using a single lighting setup for every shot, I created individual lighting setups (mainly using rect lights) for each camera and switched between them during renders. While this approach is more time-consuming, it allowed me to highlight the strongest details in each view and maintain an organized scene.

Conclusion

I worked on the Viper Cruiser on and off over the course of a couple of months, but my rough estimate would be around 240 hours of work in total. Though I would prefer to work on a piece like this continuously, there was a benefit to working on it in between other projects because I was able to brainstorm and refine more each time I returned to it.

Experimenting with the textures was definitely the most fun part of the process for me, and bringing the bike to life in UE5 was incredibly satisfying. Thanks again to 80 Level for the opportunity to talk about this project! If you'd like to see more of my work, you can find me on ArtStation and LinkedIn.

Alexa Ranzola, 3D Character Artist

Interview conducted by Amber Rutherford