2. Review: Sensing Important: sensors report data in their own coordinate frame Examples from the exercise Accelerometer of Nao Laser scanner Treat like forward kinematics
4. Today Perception using vision Range information from Vision Basic Image Processing Why is object recognition hard? -> “Computer Vision” with Jane Mulligan
5. Range sensing Last week Laser scanner (phase shift) Infrared (path loss) Ultrasound (time-of-flight) Today Depth from focus Depth from Stereo
13. Depth from Stereo Distance between stereo pair known + distance in the image -> distance to object
14. Stereo Pairs Zero crossings of Laplacians of Gaussians Gaussians: blurred image (suppresses noise) Laplacians: edges Test how far similar edges are apart Epipolar constraints are given by the geometry of the Stereo pair
15. Other example for Convolutions: Canny Edge Detector 1. 2.+3. 4. Trace along ridges (non-maximum suppression) 15
16. Exercise: Thresholds 16 16 http://homepages.inf.ed.ac.uk/rbf/HIPR2/adpthrsh.htm Screen shots by Gary Bradski, 2005
17. Exercise: Morphological Operations Examples Morphology - applying Min-Max. Filters and its combinations Dilatation IB Opening IoB= (IB)B Erosion IB Image I Closing I•B= (IB)B TopHat(I)= I - (IB) BlackHat(I)= (IB) - I Grad(I)= (IB)-(IB)
18.
19. Why is Object Recognition Hard?The difference between seeing and perception. Gary Bradski, 2009 19 What to do? Maybe we should try to find edges …. Gary Bradski, 2005
29. Lighting is Ill-posed … Perception of surfaces depends on lighting assumptions 26 Gary Bradski (c) 2008 26
30. Contrast 27 Which one is male and which one is female? Illusion by: Richard Russell,Harvard University Russell, R. (2009) A sex difference in facial pigmentation and its exaggeration by cosmetics. Perception, (38)1211-1219