Virtual production has revolutionized filmmaking by integrating real-time visual effects into live-action footage. This blending of physical and digital worlds places immense importance on color management and visual quality to create stunning, photorealistic results. Unreal Engine 5 includes robust support for ACES color workflows and high-fidelity EXR rendering to help content creators achieve incredibly accurate color grading and preserve visual fidelity when working across different mediums.
In this in-depth look, we’ll examine how UE5’s integration with ACES (Academy Color Encoding System) and OpenEXR can streamline virtual production and enhance realism throughoptimized color pipelines and HDR image sequences.
An Overview of ACES Color Management
ACES (Academy Color Encoding System) provides an end-to-end solution for maintaining color accuracy from capture, to editing, VFX, and final delivery. Developed by the Academy of Motion Pictures Arts and Sciences, ACES fits into a virtual production workflow in the following ways:
Camera footage is captured in log format, preferably ACESlog, retaining wide dynamic range and gamut. The equivalent colour space in a Sony Venice for example would be the linear X-OCN.
In ACES, X-OCN remains in its 16 bit linear state and all the output processing is done as part of the ACES output transforms. There is no need to use an S-Log3 intermediate as ACES does all the image transforms itself.
For Arri cameras, the Arri Raw Data format can be directly converted to OpenEXR files full of ACES image data and metadata, fully conforming with the ACES image container standard (SMPTE ST 2065-4:2013, ACES Image Container File Layout)
On-set preview LUTs provide temporary normalization to Monitors.
In post, footage is brought into the ACES color space for grading and VFX work.
Final delivery encodings support various target formats like HDR10, Rec.2020, etc.
This methodology ensures colors stay true across different viewing environments and content formats. Images won’t shift or be distorted as they move through the pipeline.
Unreal Engine 5 provides native support for ACES 1.2, including the ACEScg color space designed specifically for CG rendered content. When rendering assets in UE5 for virtual production, filmmakers can match real-world camera footage and achieve consistent color management.
Implementing ACES Color Management in Unreal Engine 5
To utilize ACES color in UE5:
Import camera footage recorded in ACESlog or other log formats.
In Project Settings > Rendering > Color Grading, set the Color Grading Space to ACES.
Enable ACEScg for rendering CG content, and assign the ACES tonemapper.
For final grade, bring content into the ACES color workspace.
This maps rendering from UE5 into the ACES framework. Assets rendered in ACEScg will seamlessly composite with live footage and maintain color accuracy.
Harnessing the Power of EXR Image Sequences
While ACES facilitates color precision from scene to screen, production visuals must also retain detail, dynamic range, and fidelity. This is where OpenEXR image sequences become invaluable.
EXR is an HDR image format that uses 32-bit floating point pixels. This means EXR preserves much more color data and brightness variation than formats like 8-bit JPG or PNG. Images remain virtually lossless through compositing and editing.
Unreal Engine 5 fully supports rendering directly to EXR image sequences. This provides the following benefits for virtual production:
Wide high dynamic range for realistic lighting and shadows.
Retains fine detail for complex simulations, textures, and geometry.
Multi-channel EXR files to composite CG, green screen footage, mattes, etc.
Compatibility and flexibility with industry editing, compositing, and VFX tools.
To export an EXR sequence from UE5:
In Sequence settings, select Image Format > EXR.
Adjust Image Color Format (RGB, RGBA) and Bit Depth as needed.
Render from Sequence.
The UE5 Sequencer simplifies layering and compositing EXR files with live-action plates for unparalleled photorealism in real-time during virtual production.
Optimizing ACES and EXR Workflows on Set
To leverage these technologies on virtual production sets:
For camera footage, record in RAW or log color space. Apply preview LUTs to monitors.
Output content from UE5 in ACES for LED walls and projected backgrounds.
Use ACEScg when rendering assets and VFX from UE5 to match footage.
Capture HDRIs on set to recreate realistic lighting in UE5.
For final comps, export multi-channel EXRs from UE5, incorporating renders and live plates.
By following ACES guidelines and utilizing EXR sequences, creators can achieve incredible color precision, fidelity, and dynamic range - crucial for realistic virtual production. The enhanced images integrate seamlessly with live-action footage.
Unreal Engine 5 - The Cutting Edge of Virtual Production
Epic's renderer is optimized to support next-generation filmmaking techniques. By incorporating powerful color management through ACES and pristine visual quality with OpenEXR image sequences, Unreal Engine 5 provides a complete virtual production system to imagine impossible worlds.
What visual stories will you tell with these advanced tools? We invite you to push the boundaries and continue innovating within Unreal Engine 5.