Zachary Allen shared a short breakdown of the BMW R9T Scrambler Motorbike project, spoke about his creative approach to making game assets, and gave some tips on preparing for building complex models.
Hello everyone, my name is Zachary Allen, I am a 21-year-old 3D Hard Surface Game Artist, currently based near London in the UK. Like many 3D artists, I started my journey because of my love for video games, and my curiosity as to how they were made grew as well. I am very thankful for the opportunity to share the development and creative process regarding my recent project, BMW R9T Scrambler Motorbike.
Being a freelance automotive photographer and avid petrolhead means that some of my favorite projects are inspired by the vehicles and automotive builds that I photograph or come across. After finishing a personal project of a Porsche 911 RSR, I came across a beautiful BMW R NINET Scrambler built by FCR Original and decided to design a custom build of the factory motorbike as a game asset.
The most important decision when starting a complex model like this is to decide on the themes and then gather a wide variety of references for the project. Gathering blueprints and technical drawings of the bike was my first step before using websites such as eBay to find unique shots of individual parts of the engine or frame- that would otherwise be hidden by the bodywork or structure. Another useful option is to buy a scale model of the vehicle as it allows you to look at every angle- sometimes they come with a blueprint page too!
Using the aligned blueprints for the basic shapes, I could begin to model the main parts of the motorbike. When modeling the more curved/complicated shapes, such as the fuel tank on this motorbike, it is much easier to use a low poly form that you can modify and adapt before subdividing.
However, when modeling the simpler forms on the rest of the motorbike, I create a high-poly model before creating the low-poly model by removing topology from areas that do not need it. This allows me to ensure that the motorbike's silhouette stays consistent between the high poly and low poly optimized models. Before I start the UV process, I will clean up the model by using face-weighted normals, removing the pillow-like normals that could cause lighting issues in Unreal.
UVs and Baking
I watched a conference on GDC Vault by Naughty Dog regarding the workflow used for modeling the hero vehicles in The Last of Us Part II and Uncharted 4. They highlighted their use of varied texture set sizes based on the importance of certain parts of the car, which assists in optimizing the game asset. The texel density must be kept consistent across different texture sets to ensure equal texture quality across the asset. Overlapping UVs on parts of the model that are symmetrical is another useful way to optimize your UV space.
When it comes to baking, you cannot entirely prevent artifacts produced by UV seams. However, you can minimize their effect by applying UV cuts to hard edges and hiding them in areas that won't be visible to the player. Ensuring that your UVs are as straight as possible is another important method of preventing this.
Texturing is my favorite part of the pipeline. This is where you have the most artistic freedom during your project. I always approach texturing with the same attitude: don't be boring! Don't just texture a brand-new car; apply some dust, scratches, or dirt. Your asset should tell a story about its life – that's how artists immerse the player in these virtual worlds and texturing is a great way to do this. I will create a short backstory about the owner, where the asset has been, and how far it has traveled. This can be used to influence how I texture my model:
- Base materials – make sure to apply slight color variation to the layers;
- Custom Alpha/ Normal Stamps – these can be created very quickly in photoshop and apply additional detail to the model in Substance 3D Painter;
- Weathering – add variations in roughness by using masks and paint layers to create more unique wear to the bodywork. Using the roughness view can be useful in showing the variation at this point. I also like to add a small amount of dust to crevices and covered areas of the motorbike – once more preventing that showroom feel. I will also add a final dirt pass using multiple generators and mud variations to the tires, mudguards, and underside of the body..
When it comes to rendering, I find it helpful to locate an image of the real-world asset and then recreate the lighting from that image as closely as possible. It's also helpful to consider the type of lighting equipment used to create the shot. If it's created using a standard bulb, the lighting will be slightly warm, but if it's from an LED, there will be a slight blue tint to the lighting.
Rectangular lights in Unreal Engine 5 are incredibly useful as they serve the purpose of softboxes. I usually add a Rect light from above, paired with two slightly dimmed rect lights at the front of the model on a 45-degree angle. Adding a backlight will help the model stand out from the background and improve the overall presentation of the model. I finalize my lighting setup by adding a few fill lights with very low intensity to dark areas of the model that need to be slightly brightened.
This project was very enjoyable to complete and took around a month to produce, as I was only working on it every couple of days outside of my job. I really hope that some of my advice will be useful to you; I am always available to contact via my ArtStation.