Questions tagged [computer-vision]

Questions about algorithms for processing and analyzing images and videos.

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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. ...
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1 vote
1 answer
27 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 ...
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2 votes
0 answers
29 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 ...
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1 vote
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48 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 ...
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1 vote
0 answers
75 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 ...
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2 votes
1 answer
112 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 ...
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0 votes
1 answer
47 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 ...
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2 votes
1 answer
62 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 ...
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1 vote
0 answers
46 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....
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1 vote
2 answers
2k 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 ...
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2 votes
1 answer
49 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?
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2 votes
1 answer
1k 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 ...
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-1 votes
1 answer
45 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 ...
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1 vote
1 answer
194 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 ...
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  • 151
0 votes
1 answer
120 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, ...
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4 votes
4 answers
1k 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, ...
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  • 151
1 vote
2 answers
25 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: ...
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1 vote
0 answers
62 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 ...
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1 vote
1 answer
6k views

How to convert pixel relative focal lengths to mm. [closed]

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 ...
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2 votes
1 answer
122 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 ...
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1 vote
1 answer
46 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 ...
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0 votes
1 answer
472 views

How to identify object(s) in image when given a list of all images?

I see a lot of articles and topics about OpenCV and machine learning in regards to identifying general things (like cats, or alphanumeric characters) but I am wondering if something more specific is ...
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0 votes
0 answers
68 views

Recognizing features in images (uncontrolled environment)

I have been working for some time in several kinds of image recognition. They work well. One example is , character or shape recognition. I have implemented this in an embedded processor and I can ...
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1 vote
0 answers
27 views

Want to do 3D reconstruction via simple matching

I have 2 images, called left and right images. I have some matched points $[c_l,r_l]$ and $[c_r,r_r]$ in both of them (these points are in pixel coordinates). For a 3D point in the real world, they ...
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1 vote
0 answers
56 views

Detecting shapes using CNNs in respect to other shapes in the image

I'm solving a problem of detecting an optic disc in a retina image. As you can see from the image: the optic disc is the epicentrum of the blood vessels, has an irregular circular shape and has a ...
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  • 121
3 votes
1 answer
87 views

What are some research papers or techniques that deals with fitting clothes on a human?

Given an image of a dress (from different angles), what could be ways to fit it on a human image (again multiple angles corresponding to dress)? Any link to research papers or tutorial regarding this?
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  • 149
3 votes
3 answers
743 views

Is the Tomasi-Kanade factorization still commonly used as a modern computer vision technique?

My understanding is that, in very rough terms, the Tomasi-Kanade algorithm published in 1992 describes a way to reconstruct the 3D structure of an object from multiple images of that object, given ...
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0 votes
0 answers
83 views

Does photogrammetry have non-rigid 3D reconstruction methods?

Prerequisites I've found out that photogrammetry methods allow us to fetch 3D model from set of images of a scene. I call this rigid reconstruction. There are methods of finding correspondence ...
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1 vote
0 answers
51 views

Finding a line shape objects (bars) in video images using neural networks (instead of Hough transform)

I'm currently trying to learn about computer vision stuff and I want to try it on a simple project of real time tracking of figures of players in a foosball game while the camera can be moving a ...
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  • 121
-2 votes
2 answers
94 views

Obtaining Image Measurements of a Known Object [closed]

Given the image of an adhesive tape as below, what would be possible method to find the tape radius? The image sepia toned with artificial background added. The tape itself is partially hidden.
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2 votes
1 answer
133 views

Specific Examples with Explanation of Similarities and Differences of how Distance Functions are used Across Different Fields [closed]

I took a tangent from a student project I had done a number of years ago and spent some time studying distance functions. (please note that the above link contains the full question with links as I ...
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3 votes
1 answer
1k views

Given a low resolution video, is it possible to create a higher resolution image

This question is purely theoretical as I've not been able to find anyone who's done such a thing, so my question is - is it possible, and if not why? Say you have a short video (CCTV) of a face, or ...
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  • 133
1 vote
0 answers
20 views

Convergent cameras stitching

I am currently working on a computer vision problem that involve 8 convergent cameras. I am trying to recreate a 2D image (I actually don't care of the shape of the image) that is the representation ...
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0 votes
0 answers
301 views

Multi-camera calibration wand

I am master student, and I work on project with camera tracking based on sphered Infrared (IR) markers. Now I have to implement multi-camera calibration system with a wand like this one: And I want ...
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  • 1
1 vote
0 answers
47 views

What kind of numerical image features should I use to distinguish between the attached types of poses?

I've around $500$ binary (black and white) images, of which I attach $2$ samples. I'm working on a machine learning problem of classifying images like them. I'd like to know what image features I can ...
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  • 129
1 vote
0 answers
51 views

Question about (in)dependent Haar-features and (Ada)boosting

I have an old exam question for my pattern recognition course which is stated as follows: Consider a pool of Haar features, determine if these Haar features are independent or not. Is it a problem ...
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0 votes
0 answers
33 views

Maximum Ratio of White/Black pixels in an Edge Map

Is there a maximum possible ratio of white/black pixels in an edge map? In my theoretical consideration all areas in an image which have the same intensity are black and only the edges are white. ...
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  • 1
0 votes
0 answers
297 views

computer vision - How to construct a 3d map?

I have some good basics -I think- in computervision (using openCV) and am considering to build a quadcopter to create a 3D maps while flying. I would like to place a camera on each side of the ...
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6 votes
1 answer
188 views

using orientation sensor data to predict image points

I want to use Android's gyro/accelerometer/magnetometer to predict (over a very short time interval) how image points corresponding to a fixed object will change (without trying to scan for them in ...
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  • 191
1 vote
1 answer
109 views

Description of shape in a vector form

I would like to ask for references to algorithms that can project shape information about an object to 1 dimension. Specifically I am training a neural network to be able to identify objects with ...
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  • 111
0 votes
0 answers
124 views

More Efficient Feature Method Than Haar-Feature For Face Detection

The seminal work by Viola-Jones had the most impact in face detection. It used Haar-Feature, which is fast to compute with the help of integral image method. Is there a feature method that is more ...
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  • 281
2 votes
0 answers
60 views

How the SIFT results vary by changing some parameters

I'm studying the SIFT algorithm and I have some problem understanding its operation, in particular I don't understand how the results vary according to the parameters: number of octaves, number of ...
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3 votes
0 answers
108 views

How can color spaces be compared?

I am currently working on image classification methods. One group of preprocessing methods are color space transformations. While there are "traditional" color spaces like RGB (the raw data), HSV, LUV,...
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0 votes
0 answers
41 views

What is the best way to find similarity between two bodies?

Suppose we have two human bodies. We need to find some number that represents a similarity score between the two bodies. However in order to achieve that we need to find the similarity between the ...
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0 votes
0 answers
167 views

Reversible 2D Shape Descriptor

This is a research problem and I am just wondering if there is any already existing answer in any computer vision related paper that may have skipped my notice since this is not my active area of ...
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0 votes
0 answers
20 views

Create 2D panoramas from 3D image

Given a 3D greyscale image (particularly a dental scan) I have localized a jaw on it, i.e. made jaw's voxel intensity values much higher than others. Using this, how can I create a 2D panoramas from ...
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  • 101
1 vote
0 answers
597 views

Why are SIFT features significantly different after simply re-sizing image?

I'm new to SIFT and was surprised by how much the features changed after resizing an image. Here's the images I used for testing: Original: Resized: Cropped: After running SIFT on those 3 images, ...
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7 votes
0 answers
2k views

Detecting the damaged regions in cars

Detecting the regions where a car has been damaged and the extent to which it has been damaged is a very interesting problem. It has potential applications in automatic auto insurance claims. ...
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1 vote
0 answers
65 views

Up to what extent the hypothesis of piece wise constant intensity values is valid in ocean images?

Usually, in MR images one hypothesis research communities are making is, " the spatial intensity distribution is piecewise constant and that each tissue corresponds to a unique grayscale level. Based ...
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2 votes
0 answers
255 views

Geometric interpretations of midpoint algorithm, homogeneous linear least squares and nonlinear least squares method in 3D reconstruction?

In "Multiple View Geometry in Computer Vision" Chapter 12. Structure Computation, page 310-313, triangulation is used for point 3D reconstruction. There are three methods mentioned: Midpoint method ...
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