Questions tagged [computer-vision]

Questions about algorithms for processing and analyzing images and videos.

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Queueing Delay Calculation

I would like to ask a question regarding queueing delay. All packets have the same size: L=14*10000bits The link capacity is 1000000bps The processing delay is 2us. The propagation delay is 300us. if ...
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How reduce image noise and get only specific object?

I working in road lines detection, this my code : ...
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What might be a suitable clustering algorithm to split different parts in dense optical flow?

I want to split the main part(like people) in optical flow from the background, but I don't konw how to start. I think one way is to use some kind of clustering algorithm, first split the optical flow ...
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1 answer
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Is it possible to measure how fast the humans are moving their bodies with different level(slow, normal, fast) from video?

Examples like swinging both of their hands squat walking around jump around etc Is it possible to perform this in real time under crowded scene without depth information? I can find out the "...
1 vote
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grouping/clustering of lines using Hough transform

I am new to Hough transform, though I have some basic idea about it. I am currently trying to fit the best line to a cluster of points $\left(x_i, y_i\right), i = 1,2,\cdots , N$, where there are ...
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Computer Vision techniques to find the slope of the buildings with respect to the ground?

I want to find the slope of the building with respect to the ground which means that I need to find how tilted is the building with respect to the ground through computer vision or any other ...
-1 votes
1 answer
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How to show invariance under additive and multiplicative illumination changes

The task is to "Show that the transformation f -> ((ln fx)x, (ln fy)y) is invariant under additive and multiplicative illumination changes." From my lecture notes, for ((ln f)x, (ln f)y), ...
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What are the shapes of different objects in Hough space?

I'm reviewing old exam questions and got this question regarding Hough transform: What shapes do the following objects have in parameter space? lines circles with fixed radius ellipses with fixed ...
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2 votes
3 answers
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How can I smooth thousands of faces in a 3D-mesh so as to end up with 6 faces of a die?

I have a 3D scan of an object with multiple faces, for example a standard 6 face die. The scan is a point cloud file of the die. I am able to convert the point cloud into a mesh and retrieve faces ...
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Relation between machine learning and computer vision?

What is correct concept in regards to relation between machine learning and computer vision? As shown red encircled in attached snap, computer vision is a subset of machine learning or Is it an ...
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Is there a python library for generating a mass-spring model?

Given a 3D representation like mesh or point cloud, I want to generate a mass-spring model of it. By mass-spring model I mean this. Is there a python library for doing this?
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1 answer
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Count the number of lines in binary image

Consider I have the following binary image (each pixel is either 0 or 255). How to count the number of lines (they could be straight or a little curvy). For example, in the picture, there are six ...
0 votes
1 answer
48 views

Can computer vision process 3D “images” directly?

Most CV algorithms deal with 2D images produced by cameras. However, sometimes we need to process 3D “images” (I don’t know how to call them). For example, CT and MRI produce 3D radiographs. ...
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2 answers
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Interpreting results of Sobel Edge Detection

I am implementing A No-Reference Perceptual Blur Metric paper. Somewhere in the prep steps they mention the use of vertical Sobel filter for finding vertical edges. The algorithm is summarized in Fig....
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1 answer
25 views

Tolerance of object size variation for computer vision

relatively new to Computer Vision. Lets say for example, I have a sequence of images of a car driving away from a static camera into the horizon, and I want to use this image set for some bog standard ...
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Kitti dataset Pi matrix. Pi is the same with Pi_rect?

Do i understand right that Pi in KITTI calib.txt files is the same with Pi_rect in their paper?: Pi_rect from paper But what i can't understand it why last column in projection matrix in the paper ...
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What is the best way to predict a continuous score based on image characteristics(pixels)?

I have a dataset with 9912 images, what is the best way to train them based on the pixels and features of the images to be able to predict a continuous target ranging from 1 to 100? The goal is to ...
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1 answer
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Data source for Highway autonomous driving

I am working on a object detection system for autonomous driving. I have tried it in controlled environments. I would like to try it on videos taken from a camera in front of a car running on a ...
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32 views

How to convert segmentation annotations to bounding box annotations?

I am working with YOLOV5, and creating a dataset with Robolflow which requires me to enter annotations in bounding box format. I want to use a subset of the ADE20K which already has segmentation ...
2 votes
0 answers
386 views

Bold text detection

I am currently working on a project where I need to detect bold text on a multi font-size image (so no mathematic morphology possible). This detection will be used in parallel of an OCR system (with ...
1 vote
2 answers
50 views

Which algorithm is most suitable for comparing two images to find differences?

I have two images of two objects that are suppose to be exactly the same. I use one for reference and one as my model. I want to find an algorithm that will help me find on which areas these images ...
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Morphological closing by axis-aligned rectangles for run-length-encoded binary images

A binary image is encoded as a sorted array of non-overlapping runs, which represent value 1. Each run is defined by $r$, $c_s$ and $c_e$, with $c_s \leq c_e$. These are the row, starting and ending ...
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Why are point clouds useful for large datasets of geometries?

In my computer graphics course I came across this "pro" for point clouds: Useful for large datasets (>> 1 point / pixel) I'm trying to wrap my head about it, I know drawing is ...
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Is multicolor vision really necessary for CV?

Having the ability to see 2 or more colors can improve the sensitivity of nuances but greatly increases the complexity of image processing algorithms. I once thought that 3 colors are necessary for ...
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Turing Machine for Check Validity of Unary Multiplication (A=B*C)

I have a lot of difficulty with the turing machines. I understand the theory well, but I need help with a lab exercise... Design a SINGLE TAPE Turing Machine that accepts the language $a = > b \...
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Methods to interpolate between 2 topologically identical 3D meshes

I have 2 3D surface meshes. These meshes have vertex-correspondence and have the same topology (same edges and triangles connecting the vertices). However, the vertex positions (3d coordinates) are ...
2 votes
0 answers
50 views

L1 loss different scale for small or large boxes [object detection]

In this paper[1] there is a section where it is mentioned that “The most commonly used L1 loss will have different scales for small and large objects even if their relative errors are similar”. I don’...
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Is it correct to perform feature distillation when both the teacher and student model architectures are completely different

When the architectures of the teacher and student networks do not just vary by network depths but are completely different, is it logically correct to distill knowledge at feature level (say from ...
1 vote
0 answers
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Requesting help for monitoring data drift in instance segmentation model

happy to be here. I need some guidance. I am writing a project on data drift. I have trained an instance segmentation model on the Cityscapes Dataset, to detect pedestrians. The model I trained was on ...
1 vote
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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. ...
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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 ...
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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
1 answer
76 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}...
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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 (...
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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 ...
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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 votes
0 answers
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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 ...
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1 answer
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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: ...
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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 ...
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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 votes
1 answer
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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 ...
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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 ...
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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/...
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1 answer
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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. ...
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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 ...
1 vote
0 answers
209 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} ...
3 votes
2 answers
68 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 ...
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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 & \...
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1 vote
1 answer
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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 ...
1 vote
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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 ...

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