---
title: 【Unite Tokyo 2019】Unityでレイトレーシングしよう！レイトレーシング実装と最適化の解説
tags:  #unite #unity #unitetokyo #unite tokyo 2019  
author: [Unity Technologies Japan](https://www.docswell.com/user/UnityJapan)
site: [Docswell](https://www.docswell.com/)
thumbnail: https://bcdn.docswell.com/page/63EK3PPRED.jpg?width=480
description: 2019/9/25-6に開催されたUnite Tokyo 2019の講演スライドです。 パウロ シルバ（エヌビディア）  こんな人におすすめ ・Unityでレイトレーシングをやってみたい人、もしくは、やってみたけどうまくいかなかった人 ・Unityを使って美しいレンダリングをしてみたい人  受講者が得られる知見 ・Unityのレイトレーシング機能に関する基本的な理解 ・Unityのレイトレーシング機能の効果的な使い方と最適化の方法  Unityのイベント資料はこちらから： https://www.slideshare.net/UnityTechnologiesJapan/clipboards
published: September 26, 19
canonical: https://www.docswell.com/s/UnityJapan/ZNXG7K-unite-tokyo-2019unity-176172017
---
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Real-Time Ray Tracing
Paulo Silva
Developer Technology Engineer, NVIDIA


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Announcements
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Target Audience:
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Level:
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Engineers & Technical Artists
Beginner (no programming)
Intermediate (some programming)
Warning:
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This is Beta software and is still changing
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Slides will be available
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Session recording will also be available
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Outline
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History Of Ray-Tracing
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Rasterization vs Ray-Tracing
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Basic Example
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Scriptable Pipelines & DXR Details
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Performance Advice
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More Resources
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History of Ray-Tracing
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What is Ray-Tracing?
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Rendering method
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Simulates light path
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Most modern movies use it for SFX
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Photo-realistic rendering
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Car & Architecture visualization
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Rendered in unity using real-time ray tracing


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History
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Whitted 1980
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Cook 1984
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Kajiya 1986
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Shiny
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Fuzzy
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Path Tracing
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Reflections
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Motion Blur
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Rendering Equation
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Refractions
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Soft Shadows
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Diffuse Interreflections
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Shadows
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Caustics
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History
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Whitted 1980
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Cook 1984
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Kajiya 1986


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Rasterization vs Ray-Tracing
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Rasterization: Very Simplified
Vertex Shader
Rasterizer
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Pixel Shader


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Ray-Tracing: Very Simplified
Trace Rays
Intersection Test
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Shade & Trace


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Rasterization vs Ray-Tracing: Key Ideas
Rasterizer
Ray Tracing
Question
Which pixel □ does triangle △ cover?
Which triangles △ does pixel □ see?
Operation
Pixel □ in triangle △
Ray → triangle △ intersection
Streaming
Triangles △
Rays →
Inefficiency Overdraw △
Many → collisions
Speedups
Bounding volume hierarchy BVH (AABBs)
(Hierarchical) Z-buffering
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Rasterization: Hacks
SSAO
Shadow Maps
SSR
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Rasterization vs Ray-Tracing: AO
SSAO
Ray-Tracing AO
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Rasterization vs Ray-Tracing: Shadows
Shadow Maps (No baked light maps)
Ray-Tracing Shadows
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Rasterization vs Ray-Tracing: Reflections #1
SSR
Ray-Tracing Reflections
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Rasterization vs Ray-Tracing: Reflections #2
SSR
Ray-Tracing Reflections
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Basic Example
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Basic Example
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No programming needed
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Setup needed to get started
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Shows off the main features
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Reflections
Shadows
Ambient Occlusion
Global Illumination
Compare to Rasterization
Cornell Box
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System Requirements
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RTX GPU for complex Ray Tracing Effects*
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Windows 10 v1809
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Unity 2019.3b1
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Setup
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In Player settings set:
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DirectX12 (Experimental)
REALTIME_RAYTRACING_SUPPORT
ENABLE_RAYTRACING
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Basic Demo Scene
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Let’s create a Cornell Box
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Basic Demo: Add Ray Tracing
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Add the Raytracing Environment
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Basic Demo: Reflections
After
Before
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Basic Demo – Shadows
After
Before
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Basic Demo – Indirect Illumination
After
Before
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Basic Demo: Raster vs Ray Tracing
Ray-Tracing
Raster (no baked lights)
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Scriptable Pipelines & DXR Details
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Scriptable Pipelines & DXR Details
Required for next section:
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DXR shader types
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Acceleration structures
What is DXR?
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DXR = D3D12 ray tracing
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HDRP uses Scriptable Pipelines
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These use DXR ray tracing
DXR shaders in HDRP
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DXR Shaders
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Ray Generation
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Closest-hit
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e.g.: sample skybox
Any-hit
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e.g.: calculate color
Miss shader
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defines how rays start
run once per hit for transparency
Intersection
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Intersect arbitrary shapes
DXR Shader Graph
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DXR Acceleration Structures
Acceleration Structure
Bounding Boxes are Axis Aligned (AABB)
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Performance Advice
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Performance Advice - Reflections
Smooth – Coherent Rays
Rough – Rays Diverge
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Smooth reflective surfaces are cheaper than rough surfaces
Keep shaders simple when using rough surfaces
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Performance Advice -Transparency
Opaque – No Any-Hit call
Transparent – many Any-Hits calls
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Keep Any-Hit shaders simple
When possible make objects opaque (Use LOD)
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Performance Advice – Acceleration Structures
Static Object
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Dynamic Rigid Body
Correctly tag objects as static, dynamic, animated
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Animated Character


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Performance Advice – Acceleration Structures
AS
AS
AS
AS
One Object ☺
Separate Objects ☹
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Group geometry together when possible
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Performance Advice
Performance
Quality
Ray Count
Ray Length
Denoiser Quality
Small Transparent Objects
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More Resources
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More Resources
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Ray-Tracing Gems (free pdf):
http://www.realtimerendering.com/raytracinggems/
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SIGGRAPH 2018 DXR Tutorial:
http://intro-to-dxr.cwyman.org/
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Gameworks Ray-Tracing:
https://developer.nvidia.com/gameworks-ray-tracing
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DXR Specification:
https://microsoft.github.io/DirectX-Specs/d3d/Raytracing.html
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Unity HDRP DXR Build:
get 2019.3b1 from unity hub, or download the following version
https://github.com/Unity-Technologies/Unity-Experimental-DXR
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Please try real-time ray tracing
and make something amazing!
Thank You
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