Joel Crook, Character Artist
Creating the most believable characters possible starts with creating believable materials for use within the game. In development of Rise of the Tomb Raider we used a physically based rendering, or PBR, workflow which allowed us to achieve the highest fidelity Tomb Raider to date. In a PBR workflow, having textures that accurately represent the surface being created is very important. By using measured value tables derived from real world objects for hue, saturation, and luminance we were able to do just that.
On Rise of the Tomb Raider we adopted a texture workflow that is mainly tiled textures, which has several benefits but the major benefits are memory savings across multiple assets and being able to achieve higher texture fidelity through the blending of tiling textures. The majority of used textures are broken down into 5 major types; Albedo, Reflectance, Roughness, Normal and Blend maps.
Albedo Maps dictate the color of a surface and represents the light wavelengths that penetrate and diffuse throughout a surface and give a perceived color.
Reflectance and Roughness Maps operate together to dictate the specular qualities of a surface.
Reflectance is a measurement of the specular intensity, and measures the amount of light that is reflected away from a surface or how bright the reflection will be.
Roughness is a measurement of the micro-surface, or the literal roughness on a micro scale, of a surface. This map dictates the shape of the specular highlight; surfaces like glass have a very tight small highlight, while surfaces like rubber have a very broad highlight.
Normal Maps are used to dictate how the rendering engine perceives surface deformations and allows us to give the appearance of much more detail than is actually represented by the polygon mesh of a 3D object.
Blend Maps are used to dictate material placement on a model and are the way in which we blend together multiple tiling materials into a single cohesive surface shader.
By combining all of these texture maps into materials, which form multi-layered shaders, we were able to create any number of believable surface types within our characters, weapons and throughout the environment. A multitude of surfaces, such as cloth, plastics, leathers, wood, and metals, all have unique qualities that must be emulated in order to be believable and not break immersion of the player. Elements ranging from Lara’s canvas pants, to her leather boots, to her steel guns, all have different surface qualities which needed to be handled differently in order to achieve the desired result.
When you see a pair of khaki pants, most people generally would think of this as a simple surface, but in fact there is much more than what meets the eye. In the development of Rise of the Tomb Raider we created new cloth shaders to allow us to emulate real life phenomena such as Fresnel, which, put simply, is what gives cloth its distinctive fuzzy appearance that wraps light beyond the edges of the material. Emulating this natural effect makes an enormous difference when it comes to the believability of surfaces. Below is a screenshot of Lara both without and with the Fresnel enabled.
Metals in Rise of the Tomb Raider were also crucial surfaces to handle, in order to get things like weapons to look good in-game. Much of the desired effect was achieved through technical upgrades to our rendering engine, but that upgrade transitioned into new ways of handling metallic surfaces to attain believable results. Metals, unlike most other surfaces, are very unique in the way that they interact with light. The surface of metals do not really absorb and diffuse light throughout the surface, but instead, they generally reflect most or all of the light coming at them. This is the reason that metals appear so shiny and the more reflective a surface, the less light that is permitted to penetrate the surface of an object. Most of the perceived color of a metal is actually the light that is reflected away from the surface of the metal. Below is a screenshot of one of the many weapons which can be found in Rise of the Tomb Raider.
Utilizing all of this knowledge in tandem with additional surface details such as rust, dirt, and grime, we were able to create very believable physically based surfaces that give lots of character to the weapons and characters in Rise of the Tomb Raider.
Character Artist, Rise of the Tomb Raider