Track3d

[alexlib]

• thanks to Hi-D we reviewed a bit the original code from 3dptv and found the ptv.c https://github.com/3dptv/3dptv/blob/master/src_c/ptv.c that wasn't modernized and cythonized
• this branch converted this file into track3d.c and added its binding following the tracker.{pyx,pxd} concepts
• both liboptv and py_bind tests pass
• this is a faster 3D tracker that might be helpful in some cases, it does not require 3D->2D projection and cannot do what Jochen Willneff's track.c is doing for dense cases, but it is faster because it works directly in 3D

[Copilot]

Pull Request Overview

This PR modernizes the legacy ptv.c code into a new track3d.c implementation with Cython bindings while adding 3D tracking support and corresponding tests. Key changes include:

• Adding new 3D tracking routines and Cython binding methods in tracker.pyx and tracker.pxd.
• Introducing new unit tests for 3D tracking in both Python (py_bind/test/) and C (liboptv/tests/check_track3d.c).
• Updating CMake configuration and versioning to integrate the new track3d module.

Reviewed Changes

Copilot reviewed 30 out of 31 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
py_bind/test/test_tracker.py	Added new tests for 3D tracking functionality using forward steps.
py_bind/test/test_burgers.py	Introduced similar 3D tracking tests specific to the Burgers case.
py_bind/optv/tracker.pyx	Added step_forward_3d and full_forward_3d methods for 3D tracking.
liboptv/src/track3d.c	New C implementation for 3D tracking integrating track3d_loop logic.
liboptv/tests/check_track3d.c	New test suite for verifying 3D tracking results.
CMakeLists.txt files in both liboptv/src and liboptv/tests	Updated to compile and link against the new track3d module.

Comments suppressed due to low confidence (1)

liboptv/src/track3d.c:65

• [nitpick] Consider renaming 'count1' to a more descriptive identifier such as 'link_count' to improve code readability.

    int count1 = 0;  // Count of links established in level 1