Highlights: In this post we will talk about how human vision can be tricked with a Perspective Projection model, and we will present one new model, which is called Weak Perspective. Tutorial Overview: Human vision Weak perspective 1. Human vision Humans are very sensitive to this structure of parallel lines and what they convey to us. Probably most of you have seen this Muller-Lyer illusion. Which one of these lines is longer? And you probably…
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Highlights: In this post we will continue working on Harris Corner Detector. In the previous post we presented the basic idea behind this algorithm, and here we will wrap this up and show how this method works in OpenCV. Tutorial Overview: Interpreting the Second Moment Matrix Interpreting the Eigenvalues Harris Corner Response Function Harris Detector Algorithm Code 1. Interpreting the Second Moment Matrix Let’s first consider the case, where the gradient at every point in…
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Highlights: In this post we will continue an exploration of the projection modeling. The basic modeling equations will be written in the matrix form. New concepts, such as vanishing points and parallel lines in images will be explained. Tutorial Overview: Perspective imaging – matrix equations How do parallel lines in 3D world behave in the image? What is a vanishing point? 1. Perspective imaging – matrix equations Let’s start with the perspective projection model equations.…
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Perspective Imaging Highlights: In this post we’re going to talk about perspective imaging. First, there is a little bit of math that is needed for the explanations of the geometry and the configuration of the camera. Second, we will use a simplified pinhole camera model. Hence, we will not talk about focus and other “non-pinhole effects” when the rays are not in focus. When we take a photo, our 3D world is mapped into a…
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