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Camouflage Detection

Camouflage Detection. An introduction Presented by: Ani Starrenburg. General Camouflaging Strategies. Cryptic Camouflage. Little Button Quail. Traditional US Army Camouflage Pattern. General Camouflaging Strategies. Mimicry. Rose Greenbow, Confederate Spy. Dronefly.

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Camouflage Detection

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  1. Camouflage Detection An introduction Presented by: Ani Starrenburg

  2. General Camouflaging Strategies • Cryptic Camouflage Little Button Quail Traditional US Army Camouflage Pattern

  3. General Camouflaging Strategies • Mimicry Rose Greenbow, Confederate Spy Dronefly

  4. General Camouflaging Strategies • Disruption Dazzle Camouflage Sumatran Tiger

  5. General Camouflaging Strategies • Countershading Impala Non-Countershaded Warship

  6. General Camouflaging Strategies • Translucence/Transparency Seawasp Invisibility Cloak

  7. Detecting Camouflaged Objects:

  8. Camouflage Detection Methods • Standard Object Detection Methods • Edge Detection Models • Contrast Energy Detection Model • Motion Detection • Correlation Models • Gradient Models • Energy Models

  9. Edge Detectors: Laplacian Laplacian With Gaussian Gaussian Gradient

  10. Canny Detector • Optimal Edge Detector • Multiple Stage Algorithm • Perform Gaussian smoothing • Find edge strengths |G| = |Gx| + |Gy| • Detection of edge direction theta = invtan(Gy/Gx) • Relate edge direction to a direction that can be traced in an image • Apply non-maximum suppression • Use hysteresis to eliminate streaking

  11. LaPlacian or LoG • Smooth with a Gaussian mask • Calculate the second derivatives • Search for zero crossings Or • Convolve the image with the Laplacian of the Gaussian

  12. Contrast Energy (CE) Model • Uses the output signal from similarly-oriented odd o[x] and even e[x] filters. • Energy function is defined as: E2(x) = e2(x) + o2(x) • Always positive • Shows high output when o(x), e(x) or both are high.

  13. Camouflage DetectionMethods to be Discussed • Convexity-Based Detection – exploits the principle of countershading to detect camouflaged objects • Texture Detection – intensive texture analysis distinguishes camouflaged object from background. Also, uses Canny detector to bring up edges

  14. Motion Breaks Camouflage Region of common velocity is perceived As a unit and stands out against the static background

  15. Reichardt Correlation Model • Computes motion as the ratio of the partial derivatives of the input image brightness with respect to space and time. • Two spatially-separate detectors. • Output of one of the detectors is delayed. • The two outputs are multiplied to determine if there is a correlation.

  16. Multichannel Gradient Model • Uses multiple channels of higher derivatives • The more derivatives used lowers the chance of that all will be zero at the same time • Uses a least sqaures approximation of the derivatives

  17. Motion Energy Model • Uses two sets of oriented detectors(leftwards and rightwards), each composed of an odd and an even filter. • Energy is calculated by summing the squares of the two similarly-oriented filters. • Calculate opponent energy (difference of leftward and rightward results) • Normalize by dividing by static energy to give velocity estimates

  18. An aside: Research on Active Camouflage • Animals that can escape edge detection • Animals that can camouflage motion

  19. To Do List: • Apply edge detectors and contrast energy detectors to camouflaged and illusory images and view results. • Research visual models developed from observing animal behavior and development. • Research studies in psychology for further understanding of vision process.

  20. Is there a core visual system? C A M O U F L A G E A R T

  21. Bibliography • Motion Illusions and Active Camouflage, Lewis Dartnell ,http://www.ucl.ac.uk/~ucbplrd/motion/motion_middle.html • Canny Edge Detection Tutorial, Bill Green, http://www.pages.drexel.edu/~weg22/can_tut.html • Honeybee, http://www.gpnc.org/honeybee.htm • Ground-dwelling birds, http://www.birdobservers.org.au/ground_birds.htm • Sumatran tiger, http://www.saczoo.com/3_kids/20_camouflage/camouflage_disruptive.htm • Biomimicry, http://www.wordspy.com/words/biomimicry.asp • Countershading, http://www.shipcamouflage.com/ships2_3_43_countershading.htm • Translucence, http://www.gla.ac.uk/ibls/DEEB/teg/project_pages/counter_shading.htm • Canny Edge Detection, http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/OWENS/LECT6/node2.html • Optical Camouflage, http://projects.star.t.u-tokyo.ac.jp/projects/MEDIA/xv/VRIC2003.pdf • Multi-Channel Gradient Model, http://www.psychol.ucl.ac.uk/pmco/McGM.html

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