Remove SOLVEPNP_DLS And SOLVEPNP_UPNP Methods In OpenCV 5

Describe the Feature and Motivation

The OpenCV library has been a cornerstone for computer vision tasks, providing a wide range of algorithms and tools for image and video processing, feature detection, and object recognition. However, with the advent of OpenCV 5, it's time to bid farewell to two outdated methods that have been silently deprecated for over a decade. The SOLVEPNP_DLS and SOLVEPNP_UPNP methods, which were once used for solving the Perspective-N-Point (PnP) problem, are no longer supported in OpenCV 5.

A Brief History of SOLVEPNP_DLS and SOLVEPNP_UPNP

These two methods were introduced in earlier versions of OpenCV, but they have been disabled for more than 10 years now. The last attempt to revive them was in 2013, but it was ultimately rejected due to their lack of relevance and the availability of better alternatives. Despite this, the methods still lingered in the codebase, causing potential confusion and maintenance issues.

The Silent Fallback to SOLVEPNP_EPNP

If a user attempts to use the SOLVEPNP_DLS or SOLVEPNP_UPNP methods in OpenCV 5, the solvePnP method will silently fallback to SOLVEPNP_EPNP. This behavior was introduced in 2018 to ensure backward compatibility, but it also perpetuates the use of outdated methods. By removing these flags, OpenCV 5 aims to provide a cleaner and more maintainable API.

Removing the Implementation Code

To achieve this goal, the corresponding implementation code for SOLVEPNP_DLS and SOLVEPNP_UPNP will be removed from OpenCV 5. This is a breaking change, but it's essential for the library's continued evolution and improvement. The removal of these methods will:

• Avoid Potential Confusion: By removing the outdated methods, OpenCV 5 will avoid potential confusion among users who may be comparing against DLS and UPnP using OpenCV code. This will ensure that users are aware of the available alternatives and can make informed decisions.
• Remove Dead Code: The removal of the implementation code will eliminate dead code, making the library more maintainable and easier to understand.

Additional Context

While the removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods may seem like a minor change, it's a significant step towards a cleaner and more maintainable API. OpenCV 5 is designed to provide a robust and efficient library for computer vision tasks, and this change is essential for achieving that goal.

Breaking Change: What Does it Mean?

The removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods is a breaking change, which means that users will need to update their code to use the available alternatives. This change is necessary to ensure the continued evolution and improvement of the library.

Alternatives to SOLVEPNP_DLS and SOLVEPNP_UPNP

In OpenCV 5, the recommended alternatives for solving the PnP problem are:

• SOLVEPNP_EPNP: This method is a widely used and efficient solution for the PnP problem.
• SOLVEPNP_ITERATIVE: This method is an iterative solution for the PnP problem, which provides a more robust and accurate result.

Conclusion

The removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods in OpenCV 5 is a significant step towards a cleaner and more maintainable API. By removing these outdated methods, OpenCV 5 aims to provide a robust and efficient library for computer vision tasks. While this change may require users to update their code, it's essential for the library's continued evolution and improvement.

Implementation Details

To implement this change, the following steps will be taken:

1. Remove the implementation code: The implementation code for SOLVEPNP_DLS and SOLVEPNP_UPNP will be removed from the OpenCV 5 codebase.
2. Update the documentation: The documentation will be updated to reflect the removal of these methods and provide information on the available alternatives.
3. Test the changes: The changes will be thoroughly tested to ensure that the library functions correctly and efficiently.

Future Work

In the future, OpenCV 5 will continue to evolve and improve, providing a robust and efficient library for computer vision tasks. Some potential future work includes:

• Improving the PnP solver: The PnP solver will be improved to provide more accurate and efficient results.
• Adding new features: New features will be added to the library to provide more functionality and flexibility.
• Enhancing the documentation: The documentation will be enhanced to provide more information and examples on how to use the library.

Q: What are SOLVEPNP_DLS and SOLVEPNP_UPNP methods?

A: SOLVEPNP_DLS and SOLVEPNP_UPNP are two outdated methods that were once used for solving the Perspective-N-Point (PnP) problem in OpenCV. They have been disabled for more than 10 years now and have been silently deprecated.

Q: Why are SOLVEPNP_DLS and SOLVEPNP_UPNP methods being removed?

A: The removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods is a breaking change, but it's essential for the continued evolution and improvement of the OpenCV library. By removing these outdated methods, OpenCV 5 aims to provide a cleaner and more maintainable API.

Q: What are the alternatives to SOLVEPNP_DLS and SOLVEPNP_UPNP methods?

A: In OpenCV 5, the recommended alternatives for solving the PnP problem are:

• SOLVEPNP_EPNP: This method is a widely used and efficient solution for the PnP problem.
• SOLVEPNP_ITERATIVE: This method is an iterative solution for the PnP problem, which provides a more robust and accurate result.

Q: How will the removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods affect my code?

A: The removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods is a breaking change, which means that users will need to update their code to use the available alternatives. This change is necessary to ensure the continued evolution and improvement of the library.

Q: What are the benefits of removing SOLVEPNP_DLS and SOLVEPNP_UPNP methods?

A: The removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods will:

• Avoid potential confusion: By removing the outdated methods, OpenCV 5 will avoid potential confusion among users who may be comparing against DLS and UPnP using OpenCV code.
• Remove dead code: The removal of the implementation code will eliminate dead code, making the library more maintainable and easier to understand.

Q: What is the timeline for the removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods?

A: The removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods is already implemented in OpenCV 5. Users are advised to update their code to use the available alternatives.

Q: How can I get help with updating my code to use the available alternatives?

A: OpenCV provides extensive documentation and resources to help users update their code to use the available alternatives. Users can also reach out to the OpenCV community for support and guidance.

Q: What are the future plans for OpenCV 5?

A: OpenCV 5 will continue to evolve and improve, providing a robust and efficient library for computer vision tasks. Some potential future work includes:

• Improving the PnP solver: The PnP solver will be improved to provide more accurate and efficient results.
• Adding new features: New features will be added to the library to provide more functionality and flexibility.
• Enhancing the documentation: The documentation will be enhanced to provide more information and examples on how to use the library.

By answering these frequently asked questions, we hope to provide clarity and guidance on the removal of SOLVEPNP_DLS and SOLVEPNP_UPNP methods in OpenCV 5. If you have any further questions or concerns, please don't hesitate to reach out to the OpenCV community.