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LightingKillzone : Shadow FallMichal DrobotSenior Tech ProgrammerGuerrilla Games

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Intro Guerrilla Games is SCEE studio based in Amsterdam Working on two Playstation 4 titles: Killzone: Shadow Fall New IP Killzone: Shadow Fall is a launch tile Annouced during Playstation 4 reveal Running on target 1080p 30fps

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Focus Physically Based Lighting Physically Based Area Lights Rendering Pipeline

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Motivation Killzone 3 Shipped in 2011 Matured PS3 technology Considered one of generation visual benchmark titles Killzone : Shadow Fall Next generation launch title How does it compare?

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Generation change

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Motivation Physically Based Lighting Easier to achieve hyperrealism / photorealism Consistent look in different HDR environments Simple material interface for artists Easy troubleshooting and extension

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Theory

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Light Flux Irradiance = integrated light incoming from all directions (diffuse) Radiance = light incoming from one direction (specular reflection)Irradiance (E)Radiance (L)

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Courtesy of ILMImage Based Lighting (IBL)

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Courtesy of ILM

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Courtesy of ILM

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Physically Based Lighting Model Physically Based Shading Model Responsible for surface response to incoming light depending on varioussurface physical properties Physically Based Lights Responsible for light flux calculation in the scene depending on various lightswith physical properties

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Physically Based Shading : Real lifeexamples Specular Dominant part of visible lighting Every material exhibits specular lighting Angle dependent Material type dependant

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Real life lightingCourtesy of John HableDiffuse Specular

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Real life lightingCourtesy of John HableDiffuse Specular

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Real life lightingCourtesy of John HableDiffuse Specular

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Real life lightingDiffuse Specular+Courtesy of John HableDiffuse Specular

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BRDFDiffuseSpecularEye

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Fresnel‘Rough’ReflectionRefraction

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Non metals

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Metals

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Roughness‘Smooth’‘Rough’

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Roughness‘Smooth’

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Visibility / Self Shadowing

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Energy ConservativeNon - Energy Conservative

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Workflow 3 main parameters Albedo (RGB8) Roughness (R8) Specular Reflectance (RGB8) Material response Decoupled from Lighting Works in any light environment Review assets in different IBLlighting environments

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Smooth(1.0)Rough(0.0)Diffuse

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Material properties Measured values for most materials Available in physical tables Every material can be roughly definedby those parameters We provided them as Photoshopcolor swatches Base for hand painted textures

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Use case Material Old iron plate Covered in paint Scratches Bullet holes Rust

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Simplified Roughness textureThin old paint, scratched,showing off iron underneathDue weathering effects smoothenedR = HighPure rustR = very lowRusting metalR = mixed, sparkles ofmedium smooth metalBullet holeHigh temperature smoothens iron(due to impact energy)R = very highPure old paintR = medium

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Simplified Specular Reflectance textureThin old paint, scratched,showing off iron underneathSR = Low IronPure rust, non metalSR = Low, non metalRusting metal,SR = Medium, non metal,Sparkles of Low IronBullet hole exposes pure IronSR = IronPure paintSR = Low, Medium, High non metal,Depends on paint typeOld paint = LowNew paint = Medium / High

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Simplified Albedo textureWhite thin old paint, scratched,showing off iron underneathA = Dark gray (showing off metal)Pure rust,A = Rusty in range of old concreteBullet hole exposes pure IronA = Very dark (metal)White old paintA = White in albedo range of concrete(light gray)

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 Shadow Fall BRDF Based on Cook-Torrance Fresnel Smith Schlick Visiblity Function Normalization based onSpecular Reflectance Roughness as SpecularImportance Cone Angle Approximate translucency Density maps Translucency diffusion maps

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IBL Point Based BRDF

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IBL Point Based BRDF – factor visualization

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IBL Ambient BRDF – factor visualization

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IBL Ambient BRDF

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IBL Point Based BRDF

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IBL Ambient BRDF

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 Big step for the studio Artists had to adapt Training and workshops Production and Quality Win

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Physically Based Lights

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Blinn-Phong Point Light

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Blinn-Phong Point Light

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Area Lights Every light source Size Shape Intensity Art Photography Light Direction

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Spherical Light

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Disc Light

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Rectangular Light

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Texture Rectangular Light

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Area Size and Intensity

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ααpC0pC1d0d1pC0 > pC1, due to d0 > d1Result : pC0 blurier than pC1

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Irradiance Integral DA : I(p,n) = Integrate(A) [L * cos(fi) * cos(fo) * dA / d^2] dA – differential area of the light L – luminance of light A – Area of the lightnp’pd n’fifo

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npYX3D – Word SpaceX , Y – set the light frameRadiance Integral

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2D – projectedon light frameXY

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2D – projectedon light frameXYArea of integration

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XYPDF to integrateOver Area

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IES Light Profiles

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IES Light Profiles

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IES Light Profiles

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Lighting Pipeline Overview

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IBL Reflection System 3 Tier Reflection Raytrace system Realtime Glossy Reflections Localized Cubemaps Skybox

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Localized Cubemaps

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 Picture of pretty cubemap in cross with mips

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 Picture of pretty cubemap in cross with mips

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IBL Render PassBreakdown

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Render Pass BreakdownBaked Lightmaps Diffuse + Dynamic Lights

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Ambient BRDF

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Cubemaps

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Lightmap Diffuse + Dynamic Lights + Ambient BRDF * Cubemaps

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Real Time Glossy Reflections

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Real Time Glossy Reflections : Mask

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Final composite of IBL based lighting

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Render Pass Breakdown

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Takeaway Physically Based Lighting Higher quality Faster asset production Asset reuse in different environments Physical Area Lights Time to say goodbye to point lights Easier workflow High quality results Real Time Reflections Important visual clue

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We are hiring!www.guerrilla-games.com/jobs

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References Real Time Rendering 3rd Edition by Tomas Akenine-Moller, EricHaines, Naty Hoffman Physically Based Rendering, Second Edition: From Theory ToImplementation by Matt Pharr Industrial Light & Magic John Hable blog - http://filmicgames.com/