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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Find SIFT features matching between two video

I extracted SIFT features from two videos to make a matching. I need to compare each of the second video features with those stored in an array of features of the first video. I'm having trouble set the code so that when I have the correspondence I…
Sere_na
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Object detection for a post-it note

I am trying to use object detection to recognise a post-it note within a video feed. I am using emguCV for detection. I tried using the Shape Detection approach but it couldn't recognise the post-it... maybe because I was holding it up in the air so…
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Find X and Y coordinates of point in relation to the whole image

I trying to find nose tip landmark inside 2D image. It's not working 100% correct, but as first approach it fully satisfy me. vector noses; vector faces; vector eyes; Mat frame_gray; Mat matched_frame; //frame with matched…
Michal_LFC
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Improve cvFindChessboardCorners

Unfortunately, I was not able to find any solution to my question. What I'm trying to do is to improve the results using the OpenCV-method cvFindChessboardCorners in order to be able to achieve a better camera calibration, because I think that this…
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flandmark library in dev c++ for feature point detection

How to include flandmark library in dev c++? I need to find landmark points for eye. There are no proper example for using flanmark in dev c++. When i included the header files in the project directory i still get linkage error.
rprabhu
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3D reconstruction and movement of the subject

I am reading a lot about 3D reconstruction, as I want to implement it for my product using OpenCV. A thing I want to confirm is if it's possible to do 3D reconstruction of a changing scene. I will explain better. All of the articles talk about a…
aledalgrande
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crop the required area with point in hand

I have the below output with finger tips detected and the points are pushed into the vector. The below is the output I got and blue points are the information I have. With these information can I crop the finger part alone? If so can you please…
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Hough transform line follower

Okay, I want to make a program to detect a line from a camera stream. This is for al line follower robot. So if the robot know the angle of two parallel lines, he knew in which way he must ride. I perform the follow functions: Make frame gray…
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Using surf detector to find similarity between same bank denominations

Backstory , in my country there is a picture of its founding father in every bank denomination : . I want to find the similarity between these two images via surf detectors .The system will be trained by both images. The user will present the bottom…
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How to adjust "blocksize" parameter of GFTT having only the pointer returned by FeatureDetector::create function?

I use the following function to create a GFTT keypoint detector: poKpDetector1 = FeatureDetector::create( "GFTT" ); Then call the following function to adjust desired values for it's input parameters: void FuncSet_GFTT_InpParams(…
Yashil
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OpenCV Object Detection Bounding Box

I am working on Real Time object Detection using SVM in OpenCV. My objects include, book, mug, box, monitor and negative training samples. Feature Detector - SURF Sample of Each Positive Images - 200 each (acquired from Web) Negative Sample - 400…
kcc__
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OpenCV Textured object Tracking Using Filter

I am working on a project for tracking objects with many textures with many color variations. Unlike normal tracking using color masking, my target object is vastly different since it contains several dominant color distribution. I want to detect…
kcc__
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kdtree training in opencv for ORB feature detector

I am working on real time object recognition using Opancv4android, i am able to detect, extract feature points using ORB detector and descriptor extractor from the image i capture using camera . Now, i want to build a Kdtree and train them with…
Darshan
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Options when using OpenCV Feature Matching

I am trying to find different options in using the OpenCV feature matching. I am using version 2.4.4. I heard that there is a "templated" version for the brute force matching - and that i may be able to get different matching methods... So far this…
Thalia
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Confused about what Exactly an image feature is

I read about image features on wikipedia and I am still confused about what exactly they are. Term is explained in a manner such that I cant clear my confusion. 1. They represent a Class (edge is a feature and boundry is another) 2. They represent…