EXR Overscan

Shipped

What Is It

EXR Overscan is a rendering feature in Industrial CG Platform that allows Blender Cycles to calculate extra pixel margins outside of the standard delivery frame size.

When exporting to OpenEXR, the engine preserves the standard delivery resolution inside the EXR displayWindow metadata, while writing the larger overscanned canvas bounds into the dataWindow metadata. This ensures that the outer margins are written into the file without crop-scaling or stretching the delivery aspect ratio.

Why Use It

• Downstream VFX Padding — Matches standard VFX pipeline demands by providing extra border padding for lens undistortion, camera shake simulation, and 2D/3D matchmoving in compositing packages.
• Edge Stretch Prevention — Prevents black borders or pixel stretching when matchmove cameras translate, rotate, or reproject plates.
• Deep and Multi-Layer Support — Integrates seamlessly with all EXR formats, including multi-layer EXR and Deep EXR renders.

How To Enable

Overscan settings are located in the Output Properties tab, under the Overscan panel (directly below the Format panel).

1. Set your Render Engine to Cycles.
2. Disable Render Region under the Format panel (Overscan is gated off when Render Region is active).
3. Set your active file format to OpenEXR, OpenEXR Multilayer, or Deep OpenEXR.
4. Configure your overscan margins in the Overscan panel.

Gating Conditions

The Overscan panel will be greyed out if:

• A non-Cycles engine (Eevee or Workbench) is selected.
• Render Region is enabled.

Parameters

Parameter	Sizing Mode	Default	Description
Mode	Enum	PERCENTAGE	Sizing calculation method: PERCENTAGE or PIXELS.
Amount / Size	Percentage	0.0	Sizing percentage (e.g. 10.0 for 10% on all sides).
Left / Right / Bottom / Top	Pixels	0	Individual margin paddings in pixels (available only in PIXELS mode).

EXR Window Semantics

To ensure downstream software parses overscanned EXR files correctly, Industrial CG Platform adheres to the official OpenEXR window standards:

• Display Window (displayWindow): Defines the delivery frame format (e.g. 1920x1080 with origin (0, 0)). This determines the project resolution inside compositing tools.
• Data Window (dataWindow): Defines the actual bounding box of pixels stored in the file. For a 10% overscan on a 1920x1080 frame, the data window expands to 2304x1464 with an offset origin of (-192, -192).

                  Data Window (Overscanned bounds: 2304 x 1464)
    ┌──────────────────────────────────────────────────────────────────┐
    │                                                                  │
    │  (-192, -192)                                                    │
    │         Display Window (Delivery resolution: 1920 x 1080)        │
    │         ┌──────────────────────────────────────────────┐         │
    │         │                                              │         │
    │         │ (0, 0)                                       │         │
    │         │                                              │         │
    │         │                                              │         │
    │         │                                              │         │
    │         │                                  (1920, 1080)│         │
    │         └──────────────────────────────────────────────┘         │
    │                                                                  │
    │                                                      (2112, 1272)│
    └──────────────────────────────────────────────────────────────────┘

When imported into compositors, the file will automatically align to the project's standard 1920x1080 format, while the overscan pixels outside the viewport boundaries are preserved inside the bounding box (BBox) and remain accessible for transformations.

Known Limitations

• No Viewport Render Preview — There is no true live overscanned rendered image viewport preview outside the camera frame. The viewport behavior is limited to displaying an outward safety-frame guide overlay.
• Render Region Mutex — Overscan output and viewport guides are disabled when Render Region is active.
• Cycles Only — Non-Cycles renderers do not support overscan.
• Compositor Node Constraints — When rendering through a compositor File Output node, the node group must contain a live Group Output node to trigger overscan window metadata propagation.

See Also

• RNA Properties (API Reference) — The Python API properties for configuring overscan programmatically.
• Installation Guide — Details on OptiX shader cache isolation.