Extract Focus Distance

In this article, we’ll explore how to extract the focus distance curve from EXR metadata and transfer it directly into the 3DE4 Curve Editor. This process is crucial for accurate camera tracking and matchmoving, ensuring that the focus distance matches the original footage.

Step-by-Step Guide

  1. Adding the EXR Section to the Camera

Begin by adding the EXR section to your camera in 3DE4. This section contains the metadata that we’ll use to extract the focus distance.

  1. Opening the Curve Editor

Navigate to the Curve Editor:

  • Go to Edit
  • Select Extract Focus Distance from OpenEXR Metadata

A new window will open, prompting you to enter the attribute that contains the focus distance.

  1. Finding the Focus Distance Attribute

The script will attempt to automatically locate the focus distance attribute, typically named “focus” or something similar. However, metadata naming can vary, especially with new material. It’s important to verify the correct attribute name.

  • Use Nuke or any other software to inspect the metadata and confirm the attribute name
  • If the script fails to find the correct attribute or identifies it incorrectly, manually enter the attribute
  1. Checking Units of Measurement

Ensure that you verify the units in which the focus distance is specified. By default, this is usually in meters, but it’s always good practice to double-check.

  1. Applying the Focus Distance Curve

After entering the correct attribute and confirming the units:

  • Press OK.
  • The existing focus distance curve (if any) will be deleted.
  • The new curve, extracted from the EXR metadata, will be written into the Curve Editor.

To ensure everything is accurate, check a few frames manually. Compare the focus distance values against the metadata to confirm the extraction process was successful.

How to install the script

To install the script, follow the instructions provided in the “Installation.txt” file included in the downloadable archive.
The installation process is straightforward, ensuring that you can quickly integrate the script into your workflow and start using it immediately.

Tips and Troubleshooting

  • Inconsistent Metadata: If you encounter inconsistencies in metadata naming conventions, maintain a reference list of common attributes used in your projects.
  • Unit Conversion: Be mindful of the units specified in the metadata. Conversion errors can lead to incorrect focus distances.
  • Regular Checks: Periodically check frames during the extraction process to catch any errors early on.

By following these steps, you can efficiently extract and apply focus distance curves from EXR metadata, enhancing the precision of your camera tracking and matchmoving projects.

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