Questions tagged [computer-vision]
Questions about algorithms for processing and analyzing images and videos.
269
questions
1
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0answers
16 views
Disparity calculations and camera centers
I'm learning about the disparity calculations and want to calculate the distance for a known pixel. I have calibrated and rectified images already. Now I just want to calculate Z for some pixel x,y.
...
1
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0answers
15 views
How to calculate image gradient with respect to homogeneous coordinate vector?
I want to use the direct method of computing the homography between two images to estimate the plane parameters (normal and depth [= distance from camera]) of a 3D plane.
If we have two images of the ...
0
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0answers
14 views
Different types of interpolation used in computer vision
Known codition:
four pixels shown in the image $(i,j),(i+1,j),(i,j+1)$ and $(i+1,j+1)$
$a=0.9$ and $b=0.4$
I was able to calculate the bilinear interpolation using the algorithm provided by https://...
1
vote
1answer
38 views
Is the Jacobian matrix calculation process correctly on this energy function?
When I implemented the paper Dynamic Fusion published in 2015 CVPR, I came into the trouble with how to solve the energy function:
$$E(W_t, V, D_t, \mathcal{E}) = \text{Data}(W_t, V, D_t) + λ\text{Reg}...
0
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0answers
28 views
Will we be able to « see » COVID (or any other viruses) in our environment in the future?
Given that cameras, computer vision and AI are constantly evolving with greater zoom, macro, processing power... is it possible that some day cameras would be able to « scan » a room and detect COVID (...
1
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0answers
29 views
What is the best way to compare two images for similarity if the brightness of the second image was changed?
I calculate similarity percent between two images. Another image is the same with changed brightness. I've already tried comparing by pixel (euclidean distance for grayscale and 0/1 values), comparing ...
1
vote
0answers
15 views
How to correct distortion from stitching dual camera to estimate homography
I am trying to distort the image obtained from two cameras that generate a stitching image. Unfortunately, I do not have access to the cameras and I would like to know what could be the best way to ...
0
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0answers
12 views
point of view of each pixel with regard to the whole image
I am looking for a technique or an algorithm that outputs a unique number/vector for each pixel of the image. I want to give the pixel a perspective so the neighboring pixels have more visibility and ...
0
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1answer
20 views
Distance transform with variable “impedance”
The distance transform gives the distance of each pixel in a mask to the nearest zero.
E.g. lets take the Taxicab distance transform:
...
1
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0answers
13 views
Drawing a planar intersection from stereo camera
I wanted to recreate the results of this paper, where the authors draw the boundary between two parts of a building from stereo images. The authors mention that the epipole and the intersection of the ...
1
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0answers
29 views
Would a five color display have higher image quality than an RGB display?
We have five types of photo receptors in the eyes but computer color systems just use the three red, green and blue.
Three could be motivated if rod and melanopsin sensations are just linear ...
0
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0answers
14 views
How do I choose the right model for production?
I am trying to build a classification algorithm having 28 classes. These classes consists of Logo of companies like adidas , Nike etc. I have very low dataset below than 100 images and greater than 70 ...
1
vote
1answer
32 views
Which pretrained model will be best for my dataset?
I am trying to build a classification algorithm having 28 classes. These classes consists of Logo of companies like adidas , Nike etc. I have very low dataset below than 100 images and greater than 70 ...
0
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0answers
21 views
A few questions regarding simCLR
I read this paper obout simCLR and I didn't understand a few things:
What is the goal of the temperature parameter τ? How does it affect the loss?
What will be the value of the loss for a batch with ...
0
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0answers
13 views
Inverse VR-Vision, theoretical possibilities and the additional requirements
When using VR-Vision for looking around and the vision is from some point of interest, the look-around is a rotation from inside that point and it reqires a record of a 360° photo or a 360° camera ...
0
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0answers
29 views
Stuck on Ejaz and Islam's paper about Masked Face Recognition
I'm relatively new in machine learning and I am trying to put together my undergraduate thesis on masked face recognition.
I've read Ejaz and Islam's paper (available at https://www.researchgate.net/...
0
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1answer
28 views
Trying to figure out the best way to approach this problem with Computer Vision
Newbie to CV here so sorry of this is basic. Here's the deal, I have a program that I run many times. and each run I produce a screenshot. I need to compare screenshots from N-1 and N runs and make ...
0
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0answers
81 views
I think I've found a flaw in this paper: On finding a minimal enclosing parallelogram. Can someone verify it for me?
On finding a minimal enclosing parallelogram
I think the problem will occur when we only consider the first clockwise antipodal vertex. I think instead we should consider an edge when there are two ...
1
vote
1answer
24 views
How to get a heatmap of pixel influences from a Convolutional Neural Network
If I have a CNN model (let's say I'm using Tensorflow and Keras) that I've trained for a particular task. For example, let's say I've trained it to detect the difference between an apple and banana. ...
0
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0answers
32 views
Is deepfake detection viable?
I'm thinking of doing a project on deepfake detection, but I'm not entirely sure if it is viable. Based on my understanding, how it works is that deepfake generation programs have a generative and ...
0
votes
0answers
38 views
Interpreting the accuracy of solutions to the correspondence problem
I have two pictures of the same object, taken by a car travelling down the road like shown on the right side of the image below. I want to find pixels of the object in each frame that correspond to ...
1
vote
0answers
86 views
trouble recovering rotation and translation from essential matrix
I am having trouble recovering rotation and translation from an essential matrix. I am constructing this matrix using the following equation:
\begin{equation}
E = R \left[t\right]_x
\end{equation}
...
0
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0answers
15 views
Why can we not obtain a unique solution for orientation from Essential Matrix?
In computer vision, why cannot we obtain a unique solution for the projection matrix given an Essential Matrix. Why is it said that it can only be obtained upto 'scale' and what does this mean?
2
votes
1answer
31 views
Matching superimposed image
We are given two grayscale images, one of which contains a large, mostly contiguous patch from the other one. The patch can be altered with noise, its levels may be stretched, etc.
Here's an example
...
0
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0answers
13 views
Are there some papers or books that compactly elaborate the essential part of the multiple view geometry?
I am a novice to visual SLAM and computer vision. Recently I've read a paper "A micro Lie theory for state estimation in robotics" dedicated to introducing the essential part that necessary to ...
0
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0answers
42 views
Computing structure tensors
As far as I understand, the structure tensor is:
$$
M = \sum_{(x,y) \in W} \begin{bmatrix} I_x^2 & I_xI_y \\ I_xI_y & I_y^2 \end{bmatrix} =
\begin{bmatrix} \sum_{(x,y) \in W} I_x^2 & \...
1
vote
0answers
18 views
How are epipolar lines useful in computer vision?
Why do use epipolar lines and what are it's benefits in computer vision ?I am unable to find the uses of epiploar lines and how they are helpful although i am aware of epiploar geometry concepts.
I ...
0
votes
0answers
17 views
3D reconstruction from multiple images
Sorry if it's a trivial question but I'am a beginner.
I am working on 3D reconstruction from multi-images project.
I am working with these datasets.
There is a par.txt file including the camera ...
1
vote
0answers
33 views
3D Reconstruction from multiview calibrated camera
I have a calibrated camera whose intrinsics were calculated prior.
Suppose I have multi images with the same camera. Using the first two views.I have the
1) initial reconstruction using 8 point ...
0
votes
1answer
38 views
Face recognition system with a sparse dataset
I have a dataset of 100 ID's, each ID with only a single unique face image. How can I develop an effective face recognition system to recognise only these faces?
I was thinking Deep Learning but the ...
0
votes
1answer
49 views
Performing semantic segmentation on images on word documents
At the moment, I'm making a comparative analysis between two different neural networks for a class. The problem they are both trying to solve is detecting tables on documents. Below is an example of ...
1
vote
0answers
22 views
How can I compare two faces using facial landmarks?
I'm using first_order_model for an expression transfer between an video and a static image.
Part of the algorithm makes a facial comparison to get the frame in the video where the face is best ...
3
votes
0answers
14 views
Pattern detection by stacking convolutions
CNN use convolutions to perform many tasks. In some architecture, the first layer(s) are basic filters such as Gabor's. Many CNN work by stacking a number of convolution layers to build detectors ...
0
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0answers
31 views
I don't understand formula meaning of computer vision Paper
I am master degree student at Computer Science Department.
I started master degree at this year.
Now I'm reading two papers about computer vision.
Actually before time I didn't have experience about ...
1
vote
0answers
21 views
What is the best algorithm for detecting the texture of a person's clothes in real-time for a mobile robot?
I am working on the human following robot. the robot extracts a feature of clothes's texture and distinguishes between the people that they stand up in front of the robot. So, the robot needs that it ...
1
vote
2answers
67 views
Using a rotation matrix to transform/shift a pinhole camera
I have a pinhole camera model with the following extrinsic (in Earth Centered, Earth Fixed Coordinate, (ECEF) system) and intrinsic parameters.
focal length (x,y) = 55000 px, optical center = (2400,...
2
votes
0answers
15 views
Contrast detection implementation for blur detection in microscopic image
I am currently doing a project where I have to detect if the the microscopic images given are blurry. I tried canny edge detection but they seem to perform not so good in detecting blur. I realised ...
0
votes
0answers
18 views
Laser Plane Estimation for Laser-Camera system?
I have to set up a system of a laser line/ plane projector and a web camera to localize the 3D position of the laser in the camera image. I've read / come across several resources but the idea is ...
1
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0answers
38 views
Image/Video deblurring
I am currently working on an algorithm that will help to improve shaken blurry images. I know there are plenty of them, such as deconvolution, that is pretty useful though I don't really know how to "...
1
vote
0answers
55 views
Why HOG angular bins have values between 0 and 180 degrees?
I have learned that HOG angular bins have values from 0 to 180 since the algorithm uses unsigned gradients. I am failing to understand why.
As far as I know gradient orientation is calculated as
<...
1
vote
1answer
41 views
Text detection in computer vision
I'm curious about the way text recognition works in machine learning(or more generally, the question of object vs not object) in computer vision.
How are systems trained when the not-object data set ...
1
vote
1answer
13 views
“higher intensity” and “high signal intensity” in images
I'm newbie in Computer Vision and image processing.
I'm reading the article "Automated White Matter Hyperintensity Detection in Multiple Sclerosis Using 3D T2 FLAIR" and it said:
2.2.4. WMH ...
0
votes
0answers
18 views
Measuring distance in arbitrary scale point cloud
I have one point cloud(point cloud of human feet) of arbitrary scale. If I have another point cloud(of human feet) with dimensions known, can I get the dimensions of a first point cloud? How will ...
3
votes
0answers
34 views
Partial derivatives of bilinear Sampling
I'm going over the paper Spatial Transformer Networks (link). On section 3.3 they introduce bilinear sampling kernel (Eq. 5)
$$
V_{i}^{c}=\sum_{n}^{H} \sum_{m}^{W} U_{n m}^{c} \max \left(0,1-\left|x_{...
2
votes
2answers
308 views
How to detect number of specific object in an image and it's diameter(size)?
I have two images of IRON RODS (i.e only two images) and I want to detect how many rods are there in each image and get the diameter of each rod in a image?
I don'...
1
vote
0answers
63 views
RGBD alignment without explicit transformation between RGB and depth
I have a set of RGB-D scans of the same scene, corresponding camera poses, intrinsics and extrinsics for both color and depth cameras. RGB's resolution is 1290x960, depth's is 640x480.
Depth is ...
4
votes
1answer
888 views
Difference between Image Analysis and Computer Vision
I have searched the web and I have only found the differences between Image Processing and Computer Vison (also in this website too). In addition, sometimes Image Analysis is confused with Image ...
3
votes
0answers
24 views
Using colors in feature detection
Is there any feature detector or extractor that uses color information?
Detectors like SURF and SIFT and many others work with grayscale. How do you think, may be transform can be sued to generate a ...
2
votes
0answers
47 views
Do image artefacts reveal the original image orientation?
An image is taken and then rotated by an arbitrary angle and cropped. Let us assume that the original image is rather meaningless and is not aligned in any way. Given the rotated image, is it ...
0
votes
1answer
138 views
Computer Vision Techniques to find Slope of beach in the 2D Images?
What I am planning to do is to calculate the height and estimate the slope of the segmented Object. The camera will be static and the Object of Interest is the slope of the beach.
I am finding harder ...
