Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [homography]

29 questions
23
votes
2 answers

Step by Step Camera Pose Estimation for Visual Tracking and Planar Markers

I have been working on the topic of camera pose estimation for augmented reality and visual tracking applications for a while and I think that although there is a lot of detailed information on the task, there are still a lot of confussions and…
Jav_Rock
  • 1,163
  • 2
  • 11
  • 24
12
votes
2 answers

Calculating a homography based on detected lines

I know you can calculate homographies from image to camera plane using correspondence points between a "perfect model" and the image points. I'm doing it for a football pitch/field, and have used edge detection to find the white lines in the…
Henrik Kjus Alstad
  • 251
  • 2
  • 7
10
votes
3 answers

Filtering RANSAC Estimated Homographies

I am using RANSAC algorithm for homography estimation between pairs of images taken with cameras which do not have any translation between them (pure rotation and change of scale/zoom). It works well in half of the cases. The correct output looks…
Libor
  • 4,135
  • 21
  • 37
10
votes
1 answer

What is the link between the homography computed over 2 images and the homography computed over the same images upside down?

With OpenCV, I compute the homography between, say, these two images: and Don't worry about the strange white form on the right side, it is due to the smartphone holder I use. The homography, given by findHomography() function (using points…
Stéphane Péchard
  • 999
  • 3
  • 10
  • 23
10
votes
3 answers

Why normalize the data set before applying Direct Linear Transform

Direct Linear Transform (DLT for short) is a method of homography estimation, it solves the overdetermined linear system via SVD $$Ah=b$$to find a solution $h$ under constraint $\|h\|=1$. Actually it finds the least square solution which minimize…
avocado
  • 807
  • 3
  • 12
  • 19
6
votes
2 answers

Why do we need 4 points for homography but 7/8 points for fundamental matrix calculation?

Sorry if this is a trivial question but I could not find a suitable answer elsewhere. I recently learned about homography and fundamental matrices in a CV class. I understand how these matrices are calculated and how the the formulae are derived. I…
Monster
  • 173
  • 1
  • 6
5
votes
3 answers

Apply Low Pass (Smoothing) Filter on a Set of Matrices and Reject Outliers

Given a set of a $ 3 $ by $ 3 $ matrices $ {H}_{i} $. Each matrix is an Homography matrix. They are used to stabilize Video Stream. Yet some of them are outliers which creates "Jumps" in the "Stabilized Video Stream". I would like to apply Low Pass…
Royi
  • 33,983
  • 4
  • 72
  • 179
4
votes
1 answer

How are the scaling parameters included (extracted from) an essential matrix?

An essential matrix relates corresponding points between two images assuming that a camera satisfies the pinhole camera model, and can be expressed as: $$E=K'^TFK$$ where K is the calibration and F is the fundamental matrix. There are many tools to…
user17348
4
votes
1 answer

Obtain motion between image features by means of the homography matrix

I have been reading several really good answers about how to obtain camera pose (rotation, translation, etc), such as this one and this one, but I am not sure how this applies to my problem. My problem: I have two images of a planar scene (terrain…
user17348
3
votes
1 answer

Finding Homography Matrix Using Lines

I have some Points and Lines from original image and the corresponding points and lines from top view image. -> I tried to find homography using points Used OpenCV function findHomography(objectPointsPlanar, imagePoints) : It takes 4 points from…
User4680
  • 31
  • 1
2
votes
1 answer

Ground plane estimation from a single image (was: confusion about homography and calibration camera parameters)

I'm new to this multiple view geometry issues and I'm a little bit lost, and some concept are not clear at all. I have a calibrated camera ( = I have distortion coefficents, field of view, and with those I can find what is called intrinsic…
nkint
  • 914
  • 8
  • 24
1
vote
0 answers

Convert pictures from the same camera with different FOV to pictures with same FOV

I have a camera device that produce two pictures at the time: depth picture with FOV: 87° × 58° RGB picture with FOV: 90 × 65° I expect that they "share" the same objective so their origin can be considered identical. I need to make the images to…
matousc
  • 615
  • 1
  • 5
  • 16
1
vote
0 answers

Virtual camera from panorama

I'm trying to virtualize a camera from a panorama. That is, suppose I have a really big picture, for example: a soccer field. Then I want to simulate a camera that focuses on certain regions of the game. My initial idea was to use the essential…
Adria Ciurana
  • 111
  • 1
1
vote
1 answer

Measure object planar displacement on slight moving or vibrating plane

I'm working in an application where I'm tracking an object 2d displacement on a given plane and the camera is already calibrated (intrinsic) and the lens distortion has been corrected. In order to get the object displacement measurements I'm…
joe
  • 37
  • 1
  • 5
1
vote
1 answer

homography matrix problem

i have mini project to do about homography , but i am really a beginner in matlab . i have calculated the homography matrix easily by taking a set pixels from both images but the problem is how to apply this matrix to all pixels of the original…
Yesbra Bra
  • 11
  • 1
  • 1
  • 4
1
2