Physically-Based Rendering: Understanding the technology and techniques

Imagine looking at a digital image or animation and the sparkle of a surface like marble reflects light just like they do in real life. Imagine that digitally created leaves rustle as they do on a breezy day outside… This is the result of Physically-Based Rendering!

In a world where digital or 3D visualisation creates an immersive experience, you need realism. So real, in fact, that it should look like the real world and few people could guess it’s a digital creation. For example, in a Tomb Raider game, you should look at Lara Croft’s leather jacket and it should look and behave like real leather. A great example of Physically-Based Rendering can be seen in the popular TV series “The Mandalorian” where the Razor Crest, the lead character’s ship, reflects sunlight off its hull and has a weathered patina from travelling through space. 

01_Twinbru_Article_What is Physically-Based Rendering_Jun2024_Image02Physically-based rendering (PBR) offers a myriad of advantages, encompassing the creation of lifelike images, intricate material textures, and authentic lighting. These elements collectively enhance the overall quality and visual realism of rendered scenes.

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Understanding the technology and techniques 

Physically-based rendering (PBR) is a computer graphics technique that aims to simulate the physical behaviour of light and materials in a way that closely resembles the real world. By employing algorithms based on physically accurate formulas, PBR achieves photorealistic visuals by replicating how light interacts with different materials.

PBR includes essential elements such as texture maps, shaders, and rendering techniques. While shaders play a crucial role in simulating light behaviour (check out our blog on our velvet shader project for more context), texture maps enhance the realism of rendered scenes. There are various texture maps that ensure the digital image is identical to what you would see in real life. 

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There are key principles that govern PBR to ensure renderings are eye-catching and realistic:

  1. Energy Conservation: PBR ensures that the total amount of light reflected by a surface doesn’t exceed the amount it receives. This principle leads to accurate material responses to light.
  2. Fresnel Effect: The Fresnel effect describes how reflectivity varies based on light direction and viewing angle. It contributes to the authenticity of materials when viewed from different angles.
  3. Albedo: Albedo represents a material’s base colour and significantly influences its overall appearance. Accurate albedo values contribute to realistic scenes.
  4. Reflection: PBR governs how materials reflect light sources, resulting in highlights, specular reflections, and refracted light. This adds depth and authenticity to visuals.

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What’s PBR used for? 

With this technique, designers can focus on creativity while relying on physically accurate rendering. PBR is widely used in game development for realistic environments, characters, and objects. It can be used to enhance architectural renders by accurately representing building materials and helps showcase product prototypes with lifelike materials. It’s also widely used in film and animation where it’s essential for creating lifelike visuals and enhancing the overall content quality.

"PBR facilitates a sustainable workflow, fostering the consistent creation of artwork while streamlining production processes, ultimately reducing production time and enhancing efficiency. This includes the accurate simulation of final light reflected and scattered light on various surfaces, such as smooth and rough surfaces that interact with diffuse light realistically.”

- Chaos Cosmos

Twinbru also leverages PBR techniques. For each digital fabric replica that is created, the 3D fabric texture has a number of scene renders. By integrating accurate material properties, Twinbru achieves stunning visual fidelity. Whether it’s rendering a cosy fabric-covered sofa or a flowing curtain, PBR ensures that Twinbru’s scenes feel authentic and immersive. These scenes not only accurately depict the digital twin of the fabric, but they also showcase other materials and textures perfectly. It is an inspiring showcase of how our 3D fabric renderings can elevate visualisation for interiors, architecture, furniture design and manufacturing. 

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Renderings that capture the imagination

PBR isn’t just a rendering technique; it’s a bridge between imagination and reality. It’s also the new lingua franca of modern 3D pipelines. Whether you’re designing for games, architectural visualisation, or film, PBR ensures consistency across platforms. By enhancing creativity with the technique, designers can focus on aesthetics, knowing that the underlying physics will handle material interactions. By mirroring reality, it immerses viewers and enhances visual storytelling.

We know PBR is all around us and it’s exciting to be part of projects that showcase just how much the technique can achieve. As it becomes more widely used, the applications could expand into more exciting spaces where visualisations truly give us a new sensory experience and take designs from screens to reality.

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