OpenCV 5.x API coverage: video, tracking, optflow gaps

[shimat]

Summary

Audit of the video (core), tracking (contrib), and optflow (contrib) OpenCV 5.x C++ API surface against the current OpenCvSharp C# wrapper. Part of a broader coverage sweep that started from closing the geometry/segment.hpp gap (#2000/#2001).

Baseline: opencv @ 40738fb, opencv_contrib @ 755e506 (both pinned submodule commits on main).

Gaps

video / tracking — modern DNN trackers and the whole legacy tracker family are unwrapped (9 items)

• TrackerDaSiamRPN + Params (video/tracking.hpp:985-1020) — modern DNN-based tracker; not bridged or wrapped anywhere — medium
• TrackerNano + Params (video/tracking.hpp:1030-1063) — lightweight DNN tracker; not bridged/wrapped — medium
• TrackerVit + Params (video/tracking.hpp:1071-1109) — lightweight ViT tracker; not bridged/wrapped — medium
  • Note: TrackerGOTURN was removed from OpenCV entirely in 5.x — nothing to wrap there.
• Tracker.GetTrackingScore() (video/tracking.hpp:941) — missing on the wrapped base Tracker class — small
• legacy:: tracker family (tracking_legacy.hpp:72-490, opencv_contrib) — TrackerMIL/Boosting/MedianFlow/TLD/KCF/MOSSE/CSRT entirely unbridged; only the modern (non-legacy) TrackerCSRT/TrackerKCF/TrackerMIL exist today — large
• legacy::MultiTracker/MultiTracker_Alt/MultiTrackerTLD (tracking_legacy.hpp:312-454) — multi-object tracking wrapper, not present anywhere — medium
• legacy::upgradeTrackingAPI (tracking_legacy.hpp:490) — converts a legacy tracker to modern Ptr<Tracker>; only relevant if legacy trackers get wrapped — small
• TrackerKCF.MODE enum + setFeatureExtractor callback (opencv_contrib tracking.hpp:105-111,144-145) — custom feature-extractor callback API not exposed — small
• DISOpticalFlow/VariationalRefinement OOP classes (video/tracking.hpp:701-880) — dense/variational optical flow classes missing on the video side (only free-function forms exist elsewhere) — medium
• FarnebackOpticalFlow/SparsePyrLKOpticalFlow OOP create() form (video/tracking.hpp:653-908) — only free-function/superres-bound variants are wrapped — small
• findTransformECCWithMask/findTransformECCMultiScale + ECCParameters (video/tracking.hpp:422-511) — new OpenCV-5 ECC alignment additions — small
• readOpticalFlow/writeOpticalFlow (video/tracking.hpp:591,601) — .flo file I/O helpers — small
• BackgroundSubtractor.Apply mask overload (background_segm.hpp:87) — apply(image, knownForegroundMask, fgmask, learningRate) missing — small

Also flagged (cleanup, not a gap): OpenCvSharp.Tracking.TrackerTypes (src/OpenCvSharp/Modules/tracking/Enum/TrackerTypes.cs) is a stale enum from a pre-legacy-split API that doesn't map to any current factory — consider removing/repurposing once the legacy trackers land, or separately.

Internal, not user-facing (skip): feature.hpp's TrackerContribSamplerCSC/TrackerContribFeatureHAAR/TrackerStateEstimatorMILBoosting are CV_EXPORTS_W but not CV_WRAP'd — no bindable methods.

optflow — only motion-template + calcOpticalFlowSF/SparseToDense are wrapped; four algorithm families missing (5 items)

• Real cv::optflow::DualTVL1OpticalFlow (optflow.hpp:218) — naming collision, not just a gap: the existing C# DualTVL1OpticalFlow class actually binds to the cv::superres:: native functions, not cv::optflow::. The true cv::optflow::DualTVL1OpticalFlow/createOptFlow_DualTVL1 is unwrapped — medium
• createOptFlow_DeepFlow/SimpleFlow/Farneback/SparseToDense factories (optflow.hpp:165-174) — none exposed via Cv2.OptFlow — small
• OpticalFlowPCAFlow + PCAPrior + createOptFlow_PCAFlow (pcaflow.hpp:74,94,142) — entire PCAFlow API missing — medium
• RLOF family: RLOFOpticalFlowParameter, DenseRLOFOpticalFlow, SparseRLOFOpticalFlow, calcOpticalFlowDenseRLOF/SparseRLOF, createOptFlow_DenseRLOF/SparseRLOF (rlofflow.hpp:64,233,412,501,538,545,548) — entire RLOF API missing — large
• GPCTrainingSamples/GPCTree/GPCForest/GPCDetails (sparse_matching_gpc.hpp:98,154,~230,301) — Global Patch Collider, template-heavy; entirely missing — large

Notes

Effort tags: small = a native bridge function/property + thin C# wrapper; medium = a small class or multi-member accessor set; large = a substantial class or multi-class family.