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stem/Signal Proc/Image/Tracking.md
andy 5a94c5ff1a vault backup: 2023-06-06 17:01:49 
Affected files:
STEM/AI/Kalman Filter.md
STEM/Signal Proc/Convolution.md
STEM/Signal Proc/Image/Tracking.md
STEM/Signal Proc/Pole-Zero.md
STEM/Signal Proc/Transfer Function.md
STEM/Speech/Linguistics/Consonants.md
STEM/Speech/Linguistics/Linguistics.md
STEM/Speech/Linguistics/README.md
STEM/Speech/Linguistics/Terms.md
STEM/Speech/Linguistics/Vowels.md
STEM/Speech/NLP/Jargon.md
STEM/Speech/NLP/NLP.md
STEM/Speech/NLP/README.md
STEM/Speech/NLP/Recognition.md
STEM/Speech/Perception/Perception.md
STEM/Speech/Perception/README.md
STEM/Speech/Speech Processing/Applications.md
STEM/Speech/Speech Processing/README.md
STEM/Speech/Speech Processing/Source-Filter.md
STEM/Speech/Speech Processing/Vocal Tract.md
STEM/img/english-phoneme-table.png
STEM/img/formant.png
STEM/img/pole-zero-attenuation.png
STEM/img/pole-zero-feedback.png
STEM/img/pole-zero-stable.png
STEM/img/roc-right-left.png
STEM/img/roc-two-sided.png
STEM/img/spectrum-vocal-tract.png
STEM/img/transfer-stable-unstable.png
STEM/img/vowel-chart.png
STEM/img/vowel-spaces.png
2023-06-06 17:01:49 +01:00

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Challenges

  • Clutter

    • Distractors

  • Occlusion

    • Hidden by other objects

  • Objects appearance can evolve

    • Rotation, scale, camera viewpoint

  • Take new template every n frames

  • Take new template when confidence falls below threshold

Background Tracking

  • Static camera
    • Capture clean shots of background
  • Object present
    • Average enough footage
  • Background image - current video frame = difference image
    • Threshold for binary mask

Nearest Neighbour Tracking

  • Decide component with closest centroid using previous centroid
  • Not good for occlusion
    • Will snap to next candidate

Blob Tracking

  • Build colour model of object
    • Eigenmodel
  • Mask of pixels that match object
  • Use centroid as location over time
  • Pick connected component with centroid closest to previous location
  • Good for distinctive colours
    • Not for practical situations though

Template Tracking

  • Sample distinctive patch from image
  • Search all positions in video for patch
  • Use cross-correlation
  • Illumination changes
    • Brightness is uniform shift of greyscale values up or down
    • Correlated to the mean pixel value
    • Subtract means in template and frame to give invariance
    • Normalised cross-correlation