Projective geometry is an incidence geometry of colinearity preserving transformations. Its use is widespread in computer graphics, computer vision, image registration, photography, among others. Homogeneous coordinates are commonly used to represent objects (point, lines, planes etc.) in real projective geometry. These are well-known to represent translation, rotation and perspective transformation simply as matrix-vector multiplication.
Questions tagged [projective-geometry]
94 questions
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How can I find a matching between two independent sets of features extracted from two images of the same scene captured by two different cameras?
I need to find matching between two independent sets of features extracted from two images of the same scene captured by two different cameras.
I'm using the HumanEvaI data set, so I have the calibration matrices of the cameras (in this particular…
user1400151
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Spherical Coordinates from a non centered location
Assuming a pinhole camera centered at (cx,cy,cz) != (0,0,0) is there a more efficient way to compute it's projection in a spherical coordinate system centered at the origin other than performing a ray-sphere intersection for each pixel?
If the…
memecs
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Minimum number of unique parameters in a perspective matrix to map a line from image to world
Minimal part of my problem
Given:
Green lines are parallel and perpendicular (in real-world) to red line
Two distances (purple) are known
Find:
Distance x (meters), from intersection of first green line and red line to any point on that line
2D…
Abarajithan
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Python- Projecting a circle with camera.Camera class
I am currently projecting a circle with the camera.Camera class and different viewing angles.
Specifications:
Circle center -> [0 , 0, 1]
Camera center -> [0, 0, 0] (looking up the z-axis)
I used the camera.Camera class and it all seems fine, but…
TecK97
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Finding inner common tangent to a pair of conics
I have been trying to get the common tangents to two rotated ellipse. I was following the method given by Edward Doolittle in the following thread. The two ellipses are given as the equation given in Wiki.
In the Matrix form the ellipse can be shown…
Kashish Dhal
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Sampling perspective (sub)views from fisheye image
I have a problem trying to select virtual subimages (lets call them ROIs) in a fisheye image which then I want to undistort.
I have the fisheye calibration parameters following. Scaramuzza calibration model. What I would like to do is creating an…
ElPotac
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Given a closed convex curve, let a central convex curve circumscribe it, then what is the minimum of B/A?(A and B are their corresponding areas)
I guess the answer is 2, but I cannot prove it.
I mean supermum of the minimum B/A among all A.
Notice:
Central convex curve means the convex curve is symmetric about a point in it, that is, when you rotate the curve 180 degrees about the point, it…
Nan Zhang
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Why use frustum in OpenGL on top of simple projection?
Let's consider, for simplicity, a 3D scene where, after applying model and view matrices, all vertices are inside a cube [-1,-1,-1]...[1,1,1].
Based on the geometry set up shown on the image below, one can come up with a formula for projected…
user1481126
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Compute Homography Matrix based on intrinsic and extrinsic camera parameters
I am willing to perform a 360° Panorama stitching for 6 fish-eye cameras.
In order to find the relation among cameras I need to compute the Homography Matrix. The latter is usually computed by finding features in the images and matching…
makolele12
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Scikit-Image Essential Matrix Transform Clarification
So I am currently in the process of reading "Multiple View Geometry in Computer Vision" and am working on a computer vision project concurrently but I ran into something that confused me that I was hoping to get some clarification on:
Reading…
mlz7
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How to construct camera matrix from known parameters
I wish to project an image taken with a camera for which I know all parameters (focal length, sensor size, X, Y, Z, rotation (omega, phi, kappa) on a 2D plane. I know that I need to construct a camera matrix before being able to do the planar…
Jean-François Bourdon
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Why reprojection error is minimized instead of triangulation error for bundle adjustment?
For bundle adjustment optmization why is reprojection error minimized instead of traingulation error or ray-to-3d point error? Disadvantage with reprojection error is: for perspective camera, its highly dependent on depth of the camera from the…
Niranjan Kotha
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Point projection using cross-ratios goes completely wrong after certain threshold
I'm trying for a computer vision project to determine the projection transformation occurring in a football image. I detect the vanishing points, get 2 point matches, and calculate the projection from model field points to image points based on…
Jacco.Oosterhuis
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Finding the distance of an object that is able to move
I'm new to computer vision. I'm trying to solve a problem that I find interesting. My goal is take a 2 pictures of an object, that is able to move freely (like a ball). then compare the two pictures, to see if the balls elevation has risen. I've…
Joshua Jones
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Projective Transformation: Find New Pixel Location MATLAB
I am transforming my images using a protective transformation matrix. I get my transformation by doing the following, where a are 4 fixed points, and b are 4 moving points.
my_tform = fitgeotrans(a,b,'projective');
I then transform my images…
keyserSoze
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