Questions tagged [feature-detection]

Feature detection is a process in computer vision that aims to find visual features within the image with particular desirable properties. Detected features can be points, image regions or continuous curves in the image. Interesting properties can include invariance to noise, perspective transformations, or properties interesting for specific usages (e.g. tracking).

Feature detection is a process in computer vision that aims to find visual features within the image with particular desirable properties.

Detected features are some subsection of the image, and can be:

  • points (e.g. Harris corners)
  • connected image regions (e.g. DoG or MSER regions)
  • continuous curves in the image

Interesting properties can include invariance to noise, perspective transformations and viewpoint changes (camera translation and rotation), scaling (for use in visual feature matching), or properties interesting for specific usages (e.g. visual tracking).

Important information about visual features can include:

  • coordinates in the image
  • radius of the visual feature
  • scale (octave) of the image on which the feature has been extracted

After detecting the feature with some feature detection algorithm, it is usually described by a descriptor vector (several known descriptors are used today) for the purposes of visual feature matching, while the feature's position in the image can be used directly for application in tracking.

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Can we detect and track facial Landmarks using features2d from openCV?

I need to make a Fast Localization of Facial Landmark using openCV for Android. I am new to openCV and I was wondering if features2d can be used from openCV library for this purpose rather than using dlib or other libraries. If yes then which…
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How do I detect if the phone loading my website is a feature phone?

First of all, I know that feature phones aren't that popular anymore but I still want to cater for the users. What I'm asking is to be able to determine if the browser is on a feature phone instead of a smart phone. I have a stripped down version of…
user400424
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list PDF file features command line tool

where can I find command line tool which can list some PDF features, similar to mutool.exe, it shows info about fonts, but I need get more info about file i.e. : is this uses transparency or list vector objects,
Szczepan
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How can I detect multiple occurrence of of an object in an Image

Hi new to OpenCV and I am using JavaCV plugin in Unity to detect floorplan. I want to detect the position of windows, doors and few other objects in the floorplan image. First I used template matching for detection, but later I figured out it wont…
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How do I confirm if two images contain the same object?

I need to be able to determine if two images contain the same object. A perfect example would be two photos of a licence plate at different angles. I've been thinking about OCR (Optical Character Recognition), which would probably get the job done,…
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Feature detection-based localization using OpenCV

Is there any algorithm recommendation to do this? My project is using single-channel image (BW), consist of 2 images. First image is user defined which is a "map" of an area (let says room) and second image is sensor result (using RpLIDAR 360 degree…
duck
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what is l2-ball, l1 penalty and optimization for sparseness in sparse filtering?

All the information is given about the question. I am learning IRIS recognition and during this i got Sparse filtering.
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Training HOG-linear svm base on TUD-brussel data set

is there anyone ever tried to train an HOG-liner svm pedestrian detector base on The TUD-brussel dataset(which is introduced from this…
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Why doesn't RANSAC remove all the outliers in SIFT matches?

I use SIFT to detect, describe feature points in two images as follows. void FeaturePointMatching::SIFTFeatureMatchers(cv::Mat imgs[2], std::vector fp[2]) { cv::SiftFeatureDetector dec; std::vectorkp1, kp2; …
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How can I detect differences from two images and show differences?

Here's what I would like to do: I have two similar images. The images can be different in position. So I used surf feature detector. And matched those features from two images and obtained transformation matrix. And I warped first image with that…
discover
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Feature detection (NOT user agent sniffing) to perform browser detection

Our company has a business rule that we should prevent our users from accessing our application from browsers that have not been completely tested by our QA team. This business rule is not changeable and our users know ahead of time that they can…
Myer
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OpenCV: how can I interpret the results of inRange?

I am processing video images and I would like to detect if the video contains any pixels of a certain range of red. Is this possible? Here is the code I am adapting from a tutorial: #ifdef __cplusplus - (void)processImage:(Mat&)image; { cv::Mat…
mm24
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How to detect keypoints, compute descriptors and match those descriptors in OpenCV 3.0.0, Visual Studio 2013, in C++?

I have seen the documentation of OpenCV. In there, SurfFeatureDetector, SurfDescriptorExtractor and BruteForceMatcher are being used. But when I try in my code, it is showing - Error : identifier "SurfFeatureDetector" is unidentified. Same case…
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How can I save the output obtained in Motion-Based Multiple Object Tracking?

I'm using the tutorial Motion-Based Multiple Object Tracking and have been able to successfully get that to work with my video, but is it possible to save the video that I am getting as output? I tried saving it with the code as given below, but it…
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how to apply optical flow vector to detected circle only

I am working on traffic sign detection project. Circular traffic sign has been detected, now i want to calculate optical flow vector to traffic sign only but not whole image. I could find radius of detected circle but not sure how to use this to…