Questions tagged [computer-vision]
Questions about algorithms for processing and analyzing images and videos.
1
vote
0answers
6 views
When estimating camera motion from the fundamental matrix, why can translation only be recovered up to scale using epipolar geometry?
I was wondering once you have recovered the fundamental matrix F such that xFx' = 0. If you try to recover translation and rotation from F, I am told that this is possible only up to scale? Why so?
0
votes
0answers
18 views
How to use a select case in visual basic? [on hold]
If picked up in store customers gets charged regularly price.
If shipped they get charged $5 extra.
0
votes
0answers
11 views
Stereo-Camera: How do Bundle Adjustment and projective ambiguity fit together?
In the book Multiple View Geometry in Computer Vision Hartley and Zisserman write that given a stereo image pair, the viewed scene can only be reconstructed under projective ambiguity, i.e. is a ...
1
vote
0answers
13 views
Transform Image Point to Azimuth and Elevation
I'm working on an object tracker where I need to report the azimuth and elevation of targets. Both values should be scaled from degrees to unsigned 32-bit integers. For now I can ignore lens ...
1
vote
0answers
32 views
How to find corresponding points between two photos when there's a repeated pattern?
Suppose that I have two photos, I1 and I2 and I want to find a set of corresponding points between the two photos to define a homography between them. There are many algorithms for this purpose, ...
1
vote
0answers
25 views
Removing fish-eye effect
The DNG specification (page 87) describes a simple algorithm for converting a "fish-eye" photo into a regular photo (just several lines of basic geometry).
The transformation is configured using six ...
0
votes
0answers
16 views
Trace (horizontal) lines in grayscale image
I have a grayscale image with some line in it, which I would like to trace.
The first image shows a Black&White version of the image, and the send shows the image after a few morphological ...
2
votes
1answer
73 views
Do white box methods for feature extraction exist for facial recognition?
Part of something I'm working on (or rather begin working on) involves white box approaches to facial recognition. I previously worked on something for character recognition using scene segmentation ...
1
vote
0answers
13 views
Plenoptic function meaning of dx
I'm trying to understand this paper on computer vision (http://persci.mit.edu/pub_pdfs/elements91.pdf) and it talks about building a periodic table of things we can get from the plenoptic function. It ...
0
votes
0answers
12 views
Input Features to ANN
I want to classify different flower species. It's required that features computed from GLCM and color moments should be used as input features to neural network. I have some doubt whether it is ...
1
vote
1answer
24 views
Image selection for Object detection
I'm relatively new and am still learning the basics. I've used NVIDIA DIGITS in the past, and am now looking at Tensorflow. While I've been able to fumble my way around creating some models for a few ...
1
vote
1answer
23 views
After stereo image rectification, why does the relation between disparity and depth still apply?
The relation between disparity and depth is derived based on the assumption that the two cameras are parallel.
Image rectification does not make this assumption valid.
But I see in many university ...
0
votes
0answers
20 views
object measurement with MaskRCNN
I'm looking for the way to measure the size of objects in an image and I'm taking my consideration into MaskRCNN after coming to the conclusion that opencv contour detection doesn't satisfy our needs ...
1
vote
0answers
28 views
Is there ongoing research on Markov Chain Monte Carlo algorithms (other than Metropolis-Hastings) for use in ray tracing? [closed]
Metropolis Light Transport is an application of the Metropolis-Hastings algorithm. Its variants differ only in the used "mutation strategy".
Is there ongoing research on other Markov Chain Monte ...
2
votes
1answer
37 views
Hough Transform, Computer Vision
There is some thing i dont understand about Hough Transform in polar coordinates.
From wikipedia article:
"The simplest case of Hough transform is detecting straight lines. In general, the straight ...
1
vote
1answer
46 views
Comparing variable image to static image
What are Levenshtein distance algorithms, but for images?
I will have one static image (the target: what it should look like) and one variable image (actual: what the user has created)
For example,
...
0
votes
0answers
11 views
Edge tracking from a Video
I want to track an edge which is deformable throughout the video. Are there any algorithm available which can directly do the job in MATLAB? I have tried using the Lucas Kanade tracker but it can only ...
0
votes
2answers
23 views
detectEigenFeatures with polygon ROI
I am using detectEigenFeatures in the Matlab command to obtain the corner points. This function only can provide the corner points within a rectangular boundary region. But I want to extract the ...
0
votes
0answers
12 views
Cancelling the camera motion while tracking a particle
I have a video recording where a particle is in motion. I want to track the movement of the particle as accurately as possible. But the camera which is recording the particle motion is also moving (...
2
votes
1answer
41 views
The task of recognizing game units in the screenshot
I'm new to computer vision and I want to solve the task of recognizing the game units of the game Clash Royale in the screenshot.
Briefly, there are about 70 different types of gaming units belonging ...
0
votes
0answers
22 views
Understanding depth maps in computer vision
It is clear to me that a depth map shows the distance of each pixel from the camera. Can anyone tell me what is the unit of this distance and how many bits they are usually coded with ? Also, I would ...
0
votes
1answer
27 views
Sample K representative frames within a video
I have an image-based processing module that takes photos for some computer vision processing. I have many videos, but I need to sample representative frames as its inputs, preferably those frames ...
2
votes
1answer
66 views
Capsule networks for classification with limited data
Capsule networks seem to match performance of convolutional neural networks on image classification tasks (more specifically on classification of handwritten digits in the MNIST dataset) 1.
I have ...
6
votes
3answers
186 views
In lieu of neural networks and deep learning, what are some approaches to computer vision?
So much software related to computer vision relies on AI and neural networks, I wonder some of the approaches which don't use those methods. How could some of the mainstays of computer vision (eg. ...
1
vote
0answers
124 views
Backward mapping with bilinear sampler
I have some experiences with Convolutional Neural Networks before. I have a question regarding the Bilinear Sampler used in "Unsupervised Monocular Depth Estimation With Left-Right Consistency" (the ...
0
votes
0answers
166 views
How to recognize digits in water meter image
I need to read the digits of images like the one below:
From what I understand, this will involve:
Registering and segmenting the image into each individual digit
Hand labeling a bunch of these ...
4
votes
1answer
53 views
Interpreting camera matrix
I'm having some trouble interpreting the camera matrix $K = \begin{bmatrix} f_x & s & x_0 \\ 0 & f_y & y_0 \\ 0 & 0 & 1 \end{bmatrix}$ after it multiplies some 3D vector.
...
1
vote
1answer
20 views
Relationship between depth and the vertical displacement of the object between two frames
I am trying to find the relation between the vertical displacement of an object to the depth of the object.
Say, there is an object in an image and as the center of gravity of this object moves ...
0
votes
0answers
12 views
Statistical Pattern Recognition Techniques in Visual Question Answering and Image Captioning?
I'm gearing up for my bachelor's final project currently. I'm also working on my graduate course which is Statistical Pattern Recognition. There is a project in this graduate course that I have to ...
2
votes
0answers
18 views
How to find the matched SIFT features that are spatially consistent?
I have extracted DenseSIFT from the query and database image and quantized by kmeans. The challenge is to find those SIFT features that quantized to the same visual ...
1
vote
0answers
24 views
Open source implementation of Multiscale Combinatorial Grouping [closed]
I would like to use Multiscale Combinatorial Grouping for my PhD research. However, I am restricted to use open-source implementations and this one runs on Matlab.
Does anyone know of an equivalent ...
1
vote
0answers
38 views
Combining Computer Science and Humanities
I currently hold a bachelors in Computer science and a masters in Art History. I really want to combine the two and I know of Digital Humanities but I'm not completely aware of where Digital Humanists ...
2
votes
1answer
49 views
Is it possible to transfer a point from one camera to another, given n corresponding points?
I have 2 images of a scene taken at one moment by two identical cameras (similar cameras intrinsic parameters) by to arbitrary locations and at two arbitrary orientations (different cameras poses).
On ...
0
votes
1answer
15 views
Generate a dataset for binarization of text in images
I want to generate a dataset of binarized masks of scene-text images to use them to train a model. I have no previous experience in dataset synthesization especially related to font-rendering.
Can ...
2
votes
1answer
36 views
Computer vision methods without “pre-training”
I'm new to computer vision and I have a common question that I couldn't figure out with Internet or books.
As I understood, in general, there are two main approaches in modern computer vision: neural ...
1
vote
0answers
42 views
How Does a “face” tend to be defined in Face Recognition Algorithms?
So I am working on implementing YOLOv2 using my own dataset, for face detection. This requires me to prepare a training set of images annotated with the bounding box extents of faces within each image....
0
votes
0answers
19 views
Horizontal and Vertical Gabor cells in Computational Perception
In my computational perception class, my professor said that "vertically oriented Gabor complex cells provide a more precise information about the horizontal disparity than the diagonally or ...
1
vote
2answers
58 views
What is the best algorithm for image comparison in terms of speed?
Problem domain - I'm implementing a home monitoring system using smart phones. At regular intervals rear camera of the phone takes images and compare them for a change detection. This change detection ...
3
votes
1answer
40 views
UV Projection of 3D shape onto 2D images
Given a 2D image of a human face and the corresponding 3D shape, how do I project the shape onto the images to extract texture patches from them to form a partial UV map?
1
vote
1answer
126 views
Segmentation technique for handwritten text (cursive and unconstrained)
Although I am new to the computer vision domain, I am tasked with automating handwritten text recognition from bank cheques. I first did some preprocessing(blurring and binarization) and then dilated ...
-1
votes
1answer
38 views
Using computer vision instead of algorithms?
I have been thinking of a problem i have here with a calendar scheduler where i basically want to split a year into seconds and have access to the dataset of whole year.
In this year i assign blocks ...
1
vote
1answer
85 views
Machine learning - PCA and KNN on rgb images are too slow
I work with python and images of tables (taken from above). My aim is to take a photo of a random table and then find the most similar tables to it in my database. By most similar I mean tables of ...
0
votes
1answer
81 views
Convolutional Neural Network for Insects
I've recently started learning CNN's. I need a CNN that is specialized for insects detection. Dead insects will be put on a piece of paper / container, then images will be taken from a same distance, ...
3
votes
4answers
585 views
Efficiently labelling training data in machine learning
Obviously it always depends on the specific case. However, my question is how to label data efficiently without writing a source code from scratch which solves the final problem itself?
For example, ...
1
vote
2answers
18 views
Distinguishing between side-by-side liquid streams
I'm new to computer vision and am looking for advice. I'd like to perform computer vision on a spiral system, in this system a down flowing liquid separates into different regions based on density:
...
0
votes
0answers
127 views
How does Region proposal network in Faster-RCNN work and how to code one?
This question has been confusing me for a long time.
The features from a feature extractor is passed to RPN ( Region proposal network ) which gives proposals which is then passed to ROI layers and ...
1
vote
0answers
52 views
Should I go for computer science or maths? [closed]
I am in 11th grade. The only subject which I love the most is solving alegebraic equations and questions related to it. I enjoy doing trigonometry but hate the part of proving theorems. I opted ...
0
votes
1answer
729 views
How to convert pixel relative focal lengths to mm.
Ive been playing around with the Intel Realsense R200 Camera.
I am able to exact focal length in x and y i.e. fx and fy,
but only "up to scale relative to pixel width and height, respectively"
At the ...
2
votes
1answer
80 views
Camera position w.r.t. basketball court
I am new in Computer Vision. Suppose you have 8 points (players in a basketball court) in a 2D image (png photo), that is we know the pixel coordinates of each. I would like to compute camera position ...
1
vote
1answer
25 views
Perspective-Three-Point Questions
I'm following this explanation on the P3P problem and have a few questions.
In the heading labeled Section 1 they project the image plane points onto a unit sphere. I'm not sure why they do this, is ...
