Real-Time Importance Deep Shadows Maps with Hardware Ray Tracing

Introduction

This repository contains the source code and an interactive demo for the the following CGF and EGSR paper:

Real-Time Importance Deep Shadows Maps with Hardware Ray Tracing
René Kern, Felix Brüll, Thorsten Grosch
TU Clausthal, Germany

This protoype implements Importance Deep Shadow Maps (IDSM), a real-time deep shadow algorithm that adaptively distributes Deep Shadow samples based on importance captured from the current camera viewport. Additionally, we propose a novel DSM data structure built on the ray tracing acceleration structure improving performance for scenarios requiring many samples per DSM texel. We also provide commented Slang (similar to hlsl) shaders for parts of our method here.

This project was implemented using NVIDIA's Falcor rendering framework. See README_Falcor.md for the readme provided with Falcor. This prototype includes multiple anti-aliasing implementations, namely NVIDIA DLSS, AMD FSR, and Falcor’s built-in TAA implementation.

The executable demo can be downloaded from the Releases Page. Alternatively the project can be built by following the instructions in Building Falcor or the build instructions in the original readme.

Teaser:

Contents:

• Shader for Paper Methods
• Demo usage
• Testing with more Scenes
• Falcor Prerequisites (System requirements)
• Building Falcor

Shader for Paper Methods

We have seperate (commented) shaders for most steps introduced in the paper. The shaders are written in Slang, which has similar syntax to hlsl. The following sections have seperate shaders:

• 3.1.2 Distributing the Sample Budget
• 3.1.3 Creating the Sample Distribution
• 3.2.1 Creating Rays from the Sample Distribution
• 3.2.2 Acceleration Structure (Sample from the IDSM AS)
• 3.2.3 Linked List (Fetch head buffer index)

Demo usage

After downloading the demo from the release page, it can be executed using the IDSMDemo_[SceneName].bat file. We provide four scenes with the Demo which are located in the scenes folder. Two of the scenes require downloading additional resources (Emerald Square and Lumberyard Bistro). For more info on how to load your own scenes see the Testing with more Scenes section.

To change the settings of our algorithm, navigate to the IDSMRenderer group in the UI. For more information about a setting, hover over the (?). Here is an overview of the important UI elements:

For more infos on the ParticlePass see the Testing with more Scenes section.

The Ship, ManyLights and BistroExterior .pyscene have additional options at the top of the file. The .pyscenes can be found in the scene/[SceneName] folder.

Controls:

• WASD - Camera movement
• Left Click + Mouse movement - Change camera direction
• Shift - Speed up camera movement
• Q, E - Camera Down / UP
• P - Opens the profiler that shows the Rendertime for each Pass.
• F9 - Opens the time menu. Animation and camera path speed can be changed here (Scale).
• F6 - Toggels Graphs UI menu (Enabled by default)

Testing with more Scenes

Testing with other scenes is possible but requires some additional steps if particles should be used. Particles needs to be added to the .pyscene. Here is an example:

#Load scene
sceneBuilder.importScene("scene.gltf")
#Add particle material
particle = StandardMaterial('TestParticle')
particle.baseColor = float4(1.0, 1.0, 1.0, 0.7) #Optional; Color if texture is removed (RGBA)
particle.roughness = 1.0    #Material roughness
particle.metallic = 0.0     #Material metalness
particle.doubleSided = True #Mandatory
particle.thinSurface = True #Recommended
particle.loadTexture(MaterialTextureSlot.BaseColor, 'myParticleFolder/myTexture.png') #Texture
#Add particle to scene
#sceneBuilder.addParticleSystem(Name, Material, NumberOfParticles, SpawnPosition)
sceneBuilder.addParticleSystem("ParticleSystem1", particle, 1000, float3(0,-2,0))
#This adds a particle system with "1000" individual particles. The system has the name "ParticleName", the material "particle" and spawns at the position (0,-2,0). 

The particles are always quads. All properties are handled by the ParticlePass during runtime. A settings file (.prtsett) is loaded on startup if available. If not, all particle systems are initialized with a default. Here is an overview of the ParticlePass UI:

Tips:

• Use the "Reset All" button after changing a setting to immediately see the effects.
• Use between 800-3000 particles, depending on system capabilites.
• Start with a smaller particle radius and a bigger spawn radius and adjust step-by-step to avoid crashing the demo program.

Falcor supports a variety of scene types:

• Falcor's .pyscene format (more details)
  • e.g. NVIDIA ORCA
• GLTF
  • Recommended for Blender exports. Analytic light brightness may need manual adjustments.
• FBX
  • Often need manual adjustments for glass materials.
• Many PBRT V4 files:
  • e.g. Benedikt Bitterli's Rendering Resources or PBRTv4 scenes repo
  • May require manual adjustments of materials, as not all materials match Falcor's material model.

Falcor Prerequisites

• Windows 10 version 20H2 (October 2020 Update) or newer, OS build revision .789 or newer
• Visual Studio 2022
• Windows 10 SDK (10.0.19041.0) for Windows 10, version 2004
• A GPU which supports DirectX Raytracing, such as the NVIDIA Titan V or GeForce RTX
• NVIDIA driver 466.11 or newer

Optional:

• Windows 10 Graphics Tools. To run DirectX 12 applications with the debug layer enabled, you must install this. There are two ways to install it:
  • Click the Windows button and type Optional Features, in the window that opens click Add a feature and select Graphics Tools.
  • Download an offline package from here. Choose a ZIP file that matches the OS version you are using (not the SDK version used for building Falcor). The ZIP includes a document which explains how to install the graphics tools.
• NVAPI, CUDA, OptiX (see below)

Building Falcor

Falcor uses the CMake build system. Additional information on how to use Falcor with CMake is available in the CMake development documetation page.

Visual Studio

If you are working with Visual Studio 2022, you can setup a native Visual Studio solution by running setup_vs2022.bat after cloning this repository. The solution files are written to build/windows-vs2022 and the binary output is located in build/windows-vs2022/bin.