What is Real Time Rendering?

Real time rendering enables the creation of interactive 2D and 3D computer graphics at fast enough frame rates to depict smooth, continuous visuals and motion. Any application requiring instant visualization of virtual data in an immersive environment relies on real time rendering, including video games, VR/AR, design prototyping, simulation, and special effects.

The Evolution of Real Time Graphics

The capability to render even basic 2D graphics in real-time first emerged in the 1960s. Early computer displays utilized vector graphics to draw lines and polygons efficiently. However, computational power severely limited quality and frame rates.

In 1972, Atari‘s seminal arcade game Pong achieved real-time 2D graphics, rendered using a simple 700 transistor chip. This sparked the beginning of the multi-billion dollar video games industry.

Later games like 1978‘s Space Invaders introduced tile-based rendering and animated 2D sprites rendered in real-time. By the mid-80s, advanced raster 2D graphics powered games like Super Mario Bros featuring smooth scrolling backgrounds.

The 1990s marked the popularization of real-time 3D graphics, led by iconic PC games like 1992‘s Wolfenstein 3D and 1993‘s Doom. Using techniques like ray casting, textures, and binary space partitioning, these games rendered fully interactive 3D worlds at good frame rates – pioneering the first person shooter genre.

Id Software‘s Quake raised the bar further in 1996 with the introduction of true 3D acceleration using polygonal environments and lighting. Hardware 3D graphics processing units designed specifically for real-time rendering soon followed, unleashing increasingly immersive 3D worlds rendered at 60 FPS.

Today, cinematic real-time experiences displaying complex physics, advanced materials, ray tracing and resolutions up to 8K are now possible. Leading examples demonstrating the state of the art include Epic‘s Unreal Engine 5 city demo and Square Enix‘s Matrix Awakens PS5 tech demo.

Key Milestones in Real-Time Rendering Technology

YearGame/TechnologyRendering Milestone
1972PongFirst real-time 2D vector graphics
1978Space InvadersAnimated 2D sprites
1985Super Mario BrosSmooth-scrolling raster 2D backgrounds
1992Wolfenstein 3DInteractive ray-casted 3D graphics
1993DoomTextured 3D environments + lighting
1996QuakeTrue polygonal 3D worlds
2002OpenGL 2.0Programmable shader pipeline
2004Doom 3Pixel shader lighting/shadows
2007CrysisVery high real-time graphic fidelity benchmark
2008CUDA / GPGPUGeneral purpose computing on GPUs
2009OpenCLOpen standard parallel programming
2011Battlefield 3Widespread use of deferred rendering
2013UnityAccessible real-time rendering engine
2016VulkanLower overhead 3D graphics API
2018RTX / DXRReal-time ray tracing acceleration

Rasterization vs Ray Tracing

Real-time graphics are primarily rendered using one of two approaches – rasterization or ray tracing. Each method has its own distinct workflow, advantages and disadvantages:

Rasterization is a faster, more established technology that renders images by projecting and rasterizing 3D geometric models into a 2D image plane. Rasterizers convert vectors and meshes into individual pixel fragments then determine their final color. Quality rasterization relies on complex shaders, post effects, LOD and intricate hand-authored asset optimizations.

  • Rasterization Advantages:

    • Very fast at real-time frame rates
    • Hardware accelerated via GPU
    • More predictable performance
    • Simpler graphics pipelines
    • Widely adopted technology
  • Rasterization Disadvantages:

    • Approximate lighting
    • No accurate reflections
    • Limited shadows
    • Artifacts without true object representation

Ray Tracing accurately simulates the physical behavior of light by tracing paths that photons would travel in a scene. Ray intersection tests handle visibility, reflections, refractions for true photorealism. Variable rate ray tracing focuses more rays on regions of visual importance.

  • Ray Tracing Advantages:

    • Physically accurate lighting
    • Correct reflections, refractions and shadows
    • No parameter tweaking
    • Texture/mesh/shader optimization less important
    • Alleviates artist workload
    • More organic, photorealistic results
  • Ray Tracing Disadvantages

    • Very computationally intensive
    • Challenging for real-time rendering
    • Emerging technology, less mature tools

Hybrid renderers combine advantages of both approaches into a flexible pipeline. Rasterization first renders the scene efficiently using a simplified lighting model. Ray tracing is selectively blended in where needed to accurately ground elements into the lighting environment. This incremental "ray marched temporal accumulation" allows for responsive real-time frame rates with ray traced quality.

Nvidia RTX and Microsoft DirectX Raytracing define common APIs empowering GPU accelerated real-time ray tracing on compatible gaming desktops and laptops. Enthusiast-class cards like the RTX 4080 can full path trace certain scenes at 30 FPS, with performance improving each generation.

As dedicated hardware matures, real-time ray tracing will likely become ubiquitous in the future – replacing pure rasterization with a more accurate, unified simulation of light transport. This shift promises greater realism with less optimization, elevated immersion, and streamlined productivity.

Uses and Applications

Nearly every industry leveraging 3D environments or visualization relies on real-time rendering technologies:

Video Games

All modern video games across PC, consoles, mobile and VR are powered by real-time 3D graphics rendering. Approaches range from optimized rasterization pipelines to hybrid and full ray tracing methods as hardware performance allows. Target frame rates vary based on platform, but 60 FPS is the gold standard for smooth animation and response.

The global gaming market currently generates over $200 billion yearly revenue and has over 3 billion active players. Driving this massive growth is an insatiable demand from gamers for constantly improving visual fidelity and realism possible thanks to real-time innovation.

Film & Television VFX

Real-time rendering offers disruptive advantages for modern digital filmmaking and VFX workflows. Uses cases include:

  • Previsualization: Block in CG sets, environments, vehicles, animation and shot concepts in real-time early on to experiment visually before filming physical sets and locations. Provides better planning, communication with team members and exploration of creative options.

  • Virtual Production: Render digital backgrounds, sets, props and characters composited in real-time with footage of actors captured with systems like LED volumes and camera tracking solutions. Enables more dynamic camera work and editing flexibility in post.

  • Final VFX: Leverage photoreal game engines to design expansive 3D environments, simulations, digital doubles and effects often challenging to create through traditional CGI pipelines. Vastly accelerates iteration and reduces costs.

Epic‘s Unreal Engine 5 is being used on high profile productions like Disney‘s The Mandalorian. Its Lumen global illumination and Nanite geometry system achieve cinema quality assets rendered interactively. RTX ray tracing further bolsters realism for final frames.

Global Media & Entertainment Sector Revenue Projections

2021 Estimate$2.01 trillion+8.5%
2026 Projection$2.71 trillion+35%

Simulation & Visualization

Physics-based simulations running in real-time enable users to naturally visualize and immersively explore complex datasets as interactive experiences:

Manufacturing & Architecture – Smooth walkthroughs of photoreal 3D models foster rapid iteration, testing and collaboration on product designs and architectural spaces.

Digital Twins – Physically accurate recreations of factories, warehouses and cities inform predictive maintenance needs before issues arise.

Driving/Flight Training – Hyper realistic vehicle simulators leverage real-time graphics so trainees gain experience responding safely to diverse road scenarios and conditions.

Medical Imaging – Interactive MRI, CT and ultrasound scans provide doctors critical visualization insight for rapid surgical planning and diagnosis of patient anatomy.

Scientific Visualization – Researchers probe everything from molecular dynamics to astrophysics through real-time rendered data landscapes, plots and simulations. Rapid perception of phenomena that are imperceptible otherwise.

Mobile Real-Time Rendering

While PCs and consoles boast abundant GPU processing power for rendering advanced graphics, mobile poses distinct performance challenges. Constraints like restrictive thermal budgets, limited battery drain tolerance, smaller form factors and desire for mobility force compromise.

Most mobile games strategically scale back visual quality and frame rates compared to their desktop counterparts. Titles still managing impressive graphics given hardware restrictions include Genshin Impact (30 FPS), Call of Duty Mobile (60 FPS) and the Asphalt series (60 FPS). Tablets can reach 120 FPS in titles like PUBG Mobile using high refresh rate displays.

Qualcomm, Arm and Apple design efficient mobile chipsets with customized discrete GPUs that balance adequate real-time rendering capabilities against other metrics like energy efficiency. Novel technologies like variable rate shading also show promise to further mobile real-time graphics.

5G networks rollout enhances possibilities for cloud assisted rendering. Game state and input is streamed to remote servers handling heavy GPU work, compositing frames to stream back compressing video ensuring low latency. This game streaming model stands to benefit complex mobile titles relying on real-time graphics.

Leading Real-Time Rendering Solutions

Myriad software frameworks, tools and cloud services exist focused on real-time visualization, spanning open source options to enterprise grade commercial products. Some noteworthy examples include:

Unreal Engine 5 – Epic‘s ubiquitous game engine offers outstanding real-time performance thanks to opimizations like the Nanite microgeometry system and Lumen global illumination solver. Blueprints visual scripting system accelerates development.

Unity – Accessible, multi-platform game engine adored for its ease of use, extensive documentation and large asset store. Performs well across a range of hardware with features like the High Definition Render Pipeline.

CryEngine – Impressive proprietary engine lauded since Crysis for cutting edge real-time graphics. Used across games, architecture, simulation and training applications.

Autodesk Maya – Longstanding industry standard 3D animation and modeling package. Viewport 2.0 renderer empowers interactive sculpting and scene layout. Gaming exporter workflows target Unity and Unreal.

3ds Max – Another game industry mainstay tool for 3D asset creation now evolved with modern real-time rendering toolsets via plugins and robust UE/Unity connectors.

Twinmotion – Architectural visualization solution specialized for quick, easy 3D walkthroughs and fly throughs leveraging real-time ray tracing via Vulkan RT integration.

Terragen – Procedural terrain generation and visualization via advanced real-time node based shaders crafting infinite, photorealistic nature landscapes.

Amazon Lumberyard – AWS backed freemium game engine built on O3DE. Deeply integrated with AWS cloud services for multiplayer game development, hosting and analytics.

MetaHuman Creator – Epic‘s web app for crafting production quality digital humans complete with hair and clothing simulations – fast. Results easily import to Unreal Engine 5 as real-time ready avatar assets.

Omniverse – Nvidia platform for universal scene collaboration and photorealistic rendering via PhysX, RTX ray tracing and USD pipelines. Interoperable with dozens of leading 3D packages.

The Outlook for Real-Time Rendering

Real-time rendering technology has progressed tremendously since initial steps rendering Pong‘s 2D vector ball in 1972 to today‘s demonstrations of nearly photoreal, cinematic experiences running interactively.

This half century of focused, exponential evolution is thanks to continuous hardware improvements driving more performant parallel processing and specialized programming model advancements tailored for graphics workloads.

Industry analysts forecast key trends shaping real-time graphics innovation through 2030:

  • Efficiency Focus – Architectures gravitate towards smaller, more powerful GPU cores. Ultra low voltage designs target mobility. AI guides dynamic optimizations minimizing energy consumption.

  • Expanding ubiquity – Real-time tools become accessible to wider swaths of mainstream consumers and enterprise for fast, iterative workflows. Cloud services streamline adoption.

  • New modalities – Rendering expands beyond standard displays to holography, light field, augmented reality optical waveguides and brain computer interfaces.

  • Cloud assisted rendering – Cloud server farms shoulder more rendering tasks dependent on connectivity quality and latency tolerance. Edge computing minimizes lag.

  • Towards the metaverse – High fidelity simulated digital worlds underpinning hypothetical next generation persistent online immersive experiences will rely intimately on real-time graphics innovation.

However, multiple challenges stand to impede future progress if left unresolved:

  • Managing exponential complexity – Modern professional AAA game worlds present massive data management, tight optimization needs and asset streaming problems. Workflows must evolve to enable next-gen graphics scale.

  • Limited backward compatibility – Supporting legacy platforms holds back adoption of modern graphics programming models like Vulkan, DX12 and hardware like ray tracing units.

  • Prohibitive Development Costs – High end real-time experiences comparable to film VFX require enormous upfront investments, multi-disciplinary teams, and extensive sustained engineering effort.

Ongoing research distributed simulation via cloud microservices helps tame complexity. Gradual deprecation of outdated APIs and OSes will ease compatibility concerns long term. Democratizing user friendly tools give more creators access to high quality real-time rendering, amortizing costs.

The Role of AI in Real-Time Rendering Progress

AI promises to enhance and accelerate nearly every facet of future real-time rendering pipelines:

  • Content Generation – Machine learning systems like Stable Diffusion generate usable 3D assets and animations from text prompts with minimal human guidance to jumpstart projects.

  • Automatic Optimization – AI will routinely tweak asset topology, LODs and shader configurations to maximize performance on target hardware.

  • Predictive Precomputation – Intelligently prepare visual components most likely needed ahead of time based on player movement prediction and frequented zones.

  • Procedural Detail – Deep neural networks artificially hallucinate and insert fine grain details into rendered images to fake higher quality without expensive computation.

  • Upscaling – Vector based 5x-10x supersampling techniques like Nvidia DLSS Sharpen images while accelerating frame rates beyond native resolution limitations.

  • Deniable Downgrades – Perceptual visual quality metrics guide intelligent reduction of precision/effects/lighting/physics invisible to viewers automatically freeing up headroom.

  • Testing & Validation – Simulate thousands of rendered frames, gameplay sessions, asset import scenarios and configurations to catch bugs. Spot visual artifacts missed by developers.

  • Personalization – Adapt game difficulty, pacing, visuals styles/colors coded to user ability, disability needs and preferences using data analysis.

Ongoing breakthroughs across machine learning research focused on graphics tasks will provide the building blocks to make many of these AI assisted workflows a reality before 2030.

Cloud Computing‘s Expanding Role

Shift rendering workloads to leverage elastic on demand cloud infrastructure offers unique advantages:

  • Burst Rendering – Cloud GPU farm quickly generates complex frames impossible locally in time sensitive scenarios.

  • Global Illumination – Trace billions of rays to pre-bake detailed lighting offline enhancing real-time performance.

  • Simulation Offloading – Run expensive physics systems, fluids, clothing and vehicles in the cloud freeing up local Cu/Gpu resources.

Microsoft Azure offers GPU optimized VM configurations for cloud based rendering. Nvidia integrates Omniverse, its universal scene description platform built for photoreal rendering pipelines into Azure‘s cloud infrastructure. Cloudgine‘s Granite SDK similarly handles global illumination and destruction effects across distributed servers.

As 5G and fibre networks expand availability over this decade, game streaming could displace local computation entirely. Server side rendering eliminates client hardware barriers to entry while enabling more advanced graphics. However stringent latency requirements below 50ms pose adoption challenges globally.

Regardless, the cloud stands poised to substantially accelerate innovation in real-time rendering – especially for teams lacking access to expensive local GPU clusters. Hybrid pipelines balancing the strengths of local and remote hardware best serve users across contexts.

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