January 9, 2020

Real-time ray tracing in Unreal Engine - Part 3: automotive design and visualization

Automotive & Transportation

Ray Tracing

Visualization

By Thomas Convard

Many of us have heard the claim that, these days, the differentiating feature for the discerning motorist looking for a new set of wheels is the number of cupholders. And fuel economy surely plays a factor in today’s climate-conscious and wallet-watching society. But in reality, a car’s physical appearance is still perhaps the key influencer for most of us.

The curves and lines that define a car’s profile are its signature, and the way they react to different lighting conditions is a critical component of a vehicle’s design. And what shows off those shapes the most? Reflections. Part of the reason so many people wash their cars on a regular basis is that dirty cars don’t reflect the light as they were intended to, and a matte vehicle loses a huge amount of its appeal.

So from creating the initial concept to marketing the final product, paying attention to how light plays on the car’s surface is of paramount importance. Until recently, accurately portraying reflections required time-consuming offline rendering that could take many minutes or even hours for a single frame.

With the advent of real-time ray tracing in Unreal Engine powered by NVIDIA RTX GPUs, demonstrated prior to its public release at SIGGRAPH 2018 in "The Speed of Light” Porsche 911 Speedster Concept, automotive designers can make sure their designs incorporate the most aesthetically pleasing reflections, while sales and marketing teams can show off the final products to their best advantage.

A better creative flow for concept creation

Designing and refining a car’s surface curves naturally starts at the concept phase. Here, real-time ray tracing enables designers to quickly iterate on design concepts and to use accurate shadows and lighting to assess their aesthetics.

While waiting for an offline render can interrupt the creative flow, with real-time ray tracing, designers get instant feedback. Moreover, the ability to continuously change the point of view while seeing the full-quality result enables them to check lighting behavior on local shape features they’ve just created.

The result is fewer errors and more viable designs ready for further development earlier in the production cycle.

Nailing down the details

Later in the automotive development process, during the detailed design phase, engineers and designers need to assess the perceived visual qualities of the model that is destined to be manufactured.

This stage includes validating that exterior surfaces provide aesthetically pleasing reflections. In addition, designers need to verify that the gap and flush measurements between adjacent surfaces are consistent and acceptable, and the way light behaves over the surfaces helps in this regard.

When it comes to interiors, ray tracing also enables real-time global illumination, where the contribution from light bounced off other surfaces affects a surface’s final color, just as it does in real life. This is useful for validating how interior surfaces—such as cloth, leather, plastics, and wood—appear in ambient lighting.

Traditionally, the automotive industry uses clay models and physical prototypes at this stage, which are both expensive and time-consuming to produce. By replacing or supplementing these with digital tools, companies can make significant savings in both time and cost.

Beauty shots and digital showrooms

Once the finished vehicle is ready for the production line, it’s the turn of sales and marketing. With Unreal Engine, you can create high-quality still images for glossy brochures, videos for commercials, interactive point-of-sale configurators, and digital showrooms, all before the finished vehicles are produced—and all media can benefit from real-time ray tracing.

The way a reflective object is lit for rendering determines how effectively its form is communicated. Lighting a reflective object for a beauty shot is harder than lighting a matte one due to its dependence on the camera position. Without real-time feedback, it can be a long, difficult process filled with trial and error.

With real-time ray tracing, however, you can place objects and lights (such as soft boxes and reflection cards) and see them properly and accurately reflected in real time, and you can iterate quickly to get the look you want. Faster iterations mean you can achieve a better end result, in far less time, and ultimately, that translates to far less cost. It’s fun, it’s fast, and it’s a game changer for automotive rendering.

Ready to see what real-time ray tracing can bring to your automotive design and visualization projects? Download Unreal Engine today.

This article is part of a series on real-time ray tracing in Unreal Engine. You can also read Part 1: the evolution and Part 2: architectural visualization. Stay tuned for part 4 of the series, which will be dedicated to media and entertainment, in the near future.