Questions tagged [computer-vision]
Mathematical methods used in widely understood computer vision.
245 questions
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On the performance of an autonomous vehicle's pedestrian-detection system [closed]
I am analyzing the performance of an autonomous vehicle’s pedestrian detection system and I want to ensure I’m interpreting the scenario correctly in terms of confusion-matrix components.
Here is the ...
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Why is a linear triangulation method with SVD unsuitable for projective reconstruction?
I am studying a linear method for triangulation that uses Singular Value Decomposition (SVD) to estimate a 3D point P from multiple camera views. The method formulates a linear system of equations $AP=...
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How to interpolate image embedding from one image frame to another
I am new to image processing from the perspective of embedding. Currently a lot of research and papers are being published in deep learning community for object detection using transformers. I have a ...
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Fitting general but "smooth" convex shape to points
I am aware that there are algorithms to fit, say, an ellipse to a bunch of given points on a plane. For instance, this SO question has answers which feature both literature on the algorithms and ...
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Identifying the 3 Euler angles of rotation from 2 perspective images of a rectangle
I've worked on this problem for 3 days and I've decided to reach out for help. I have 2 images of the same rectangle (see figures). In the first image I have a 2D rectangle, and I know its height and ...
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Optimal rotation matrix
Context: I am trying to adapt the Rigid point set registration algorithm from Point Set Registration: Coherent Point Drift to include rotation information.
My problem can be stated as follows:
$\max_{...
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Book Recommendation on Edge or Boundary Detection
I have recently being interested in the estimation of discontinuities or jumps from noisy signals or densities and spend some time reading "Image Processing and Jump Regression Analysis" by ...
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"Histogram Equalization" Problem
Here we deal with the problem of Histogram Equalization.
Let $\Omega$ be the set of all pixels in an image, but you can just treat it as some arbitrary set in this case.
Let $f: \Omega \rightarrow \{0,...
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Moving Eyespace/Camera around Globalspace
Im having a hard time understanding the concept of moving the eyespace/camera around the globalspace mathematically. Ive checked out a lot of videos/articles etc., but tbh at this point Im just ...
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calculating relative focal length based on a cylinder
I am trying to camera match a photo of a cylinder.
The photo is taken relatively straight, and I can get a rotation matrix for the camera based on the elipsis created by projecting the top circle.
...
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Pinhole camera, rectangle projected to one parallel to axes in image.
I have a situation where I want to take a rectangle in a pin hole camera view and find which the possible corresponding rectangles in 3D space are.
Own work:
My intuition tells me that the set of ...
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Transformation/Pose of a sphere using a spherical camera model
I stumpled upon a problem that is related to the Perspective-n-Point problem (https://en.wikipedia.org/wiki/Perspective-n-Point) in Computer Vision and the Orthogonal Procrustes problem (https://en....
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how erosion works in mathematical morphology?
I have these definitions:
Let $A \subset E^N$ and $b \in E^N$. The translation of $A$ by $b$, denoted by $(A)_{b r}$ is defined as
$$
(A)_b=\left\{c \in E^N \mid c=a+b \quad \text { for some } a \in A\...
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Reversing perspective projection of cricles
I have a set of real-world images containing circles, but due to the images not being taken parallel to the circle plane, the circles appear as ellipses in the images. I need to crop out the inside of ...
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Min-Sum Belief Propagation not working on a chain model with equal unary potentials
Given is a chain factor graph as presented in the image below with the following properties:
Each node can take values 0 or 1
All unary potentials are equal (e.g. $U(a) = 0$ for every node)
All ...
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Self-Calibration in Aerial Computer Vision
I have read that there are 4 common procedures for auto-calibration in Computer Vision:
Mendonca & Cipolla's Method
Classical Kruppa's Method
Simplified Kruppa's Method
Dual Absolute Quadric ...
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Connection between image space and Hough space? [closed]
The other day I got very interested in learning about Hough Transform that is used to detect edges in images.
After going through OpenCV documentation, I still couldn't piece together an understanding ...
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For two square matrices $A$ and $B$, if $\left | A - B \right |^2_F$ is a small scalar number then can we assume $A \approx B$?
When researching a way to evaluate if two square matrices are equal or (very close to being equal) for a computer vision localization problem, I came across this Math Exchange post
Minimize the ...
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357
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Understanding distance from point to line in homogeneous coordinates
I would like to find the distance between A 2d point given as the homogeneous $P=(x, y, z)$, and a 2d line given as $L=(a, b, c)$.
I found an algorithm that does this, I can't figure out why it is ...
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Place the camera to match a given camera - object transformation
I know the pose (in camera frame) of an object related to a camera in real world (results are coming from a 6d-pose estimator).
In the simulation I want to replicate the same view and same position (...
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How to determine if an object is within a camera's frame and its position within said frame knowing the camera properties and distance?
I will list camera and lens properties that may be of use.
Camera resolution: 1280×1024 ((0,0) top left and (1279, 1023) bottom
right)
Lens Focal Length: 3.5 mm
Sensor size and lens format: 1/2&...
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1
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SVD and identifying a projectivity upto similarity
This is from Hartley-Zisserman's Multiple View Geometry in Computer Vision pg 55-56.
We are given a conic $$C_\infty^* = \begin{bmatrix}1 & 0 & 0 \\ 0 & 1 & 0 \\ 0& 0 & 0 \end{...
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Trouble with chessboard set definition
The following equation is supposed to define a set of points that produces a square grid (like a chessboard).
s is the distance between each square in the grid
w and h are the dimensions of the board ...
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How to determine the pose of a 3D ellipse given two projections to 2D of the ellipse?
This question is about whether I'm doing an optimization problem the right way, or if it can be done in a simpler way. I'll start with my problem scenario and then move into my proposed solution. I ...
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Minimization of residual in Shi-Tomasi feature extraction
I don't understand how in the following paper https://users.cs.duke.edu/~tomasi/papers/shi/TR_93-1399_Cornell.pdf (Good features to track) the residual (Eq. 3.1) is differentiated so that Equations 3....
