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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I Can't generate dll from flandmark v0.7 Plataform x86 Win 7

I'm trying to compile my flandmark but it is very complicated. C:\flandmark\libflandmark\CMakeLists.txt I put in first line: set(OpenCV "C:/opencv248/sources/cmake") It is correct ? Follow my full file CMakeList.txt: set(OpenCV…
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Line detection in Java

My main goal is to detect the little line over the left of the image: By detecting line I mean I want a line equation of this form: y = ax + b. In order to find the line, I tried using this Hough Transform java class, which doesn't return the…
Jjang
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OpenCV SIFT key points extraction isuue

I tried to extract SIFT key points. It is working fine for a sample image I downloaded (height 400px width 247px horizontal and vertical resolutions 300dpi). Below image shows the extracted points. Then I tried to apply the same code to a image…
Grant
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State of the Art solutions for automated thumbnail cropping using detection of faces and other features

I'm looking for a state of the art method to crop images to thumbnails while keeping all relevant features of the images. The images are stills from TV shows and movies. They are large (more than 1000px), sharp and usually very well balanced (hue,…
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Logitech Facial Feature tracking

for my application i want to track the facial features. i have tried some methods but none of them provided the required robustness . the first method is based on haar face detection,canny edge detection, contour finding and key points detection ,…
Dinesh Kannan
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Fixed-length HOG descriptor for variable sized images

I'm working on some object detection code, however my objects don't have a fixed size, so; skimage.feature.hog(obj) doesn't give me equal length vectors(since it uses fixed sized cells), and therefore I can't use learning algorithms on them. So, I…
utdemir
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Import MATLAB algorithm into an Android device

First, sorry for my poor english. Ok, I would like to implement an algorithm into an android device. My goal is to detect an hexagon pattern in an image/photo which is take directly on the android. I've seen that it seems to be more easily to…
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OpenCV low framerate with ORB detector

I was playing with OpenCV Mixed Processing tutorial and I experienced a good framerate (~27) when detecting features in camera frames with FAST detector. I changed the detector to ORB and the framerate dropped to around 10. Is this because ORB is…
Mikael S.
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Opencv feature description given coordinates

I have a problem with matching the interests points that I have found with harris detector. I didn't use the built-in functions of harrisDetector in opencv. Instead, I wrote the algorithm. So, I ended up with the interest points, but I don't know…
ilker
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Drawing matches from Nearest Neighbour Distance Ratio

In openCV I have adapted this tutorial code in my application http://docs.opencv.org/2.4.2/doc/tutorials/features2d/feature_homography/feature_homography.html#feature-homography I have been trying to prune the matches using the Nearest Neighbour…
Tom smith
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Comparision with grund truth image

I am currently working on object detection.I have obtained the co-ordinates of the object in the image.I am also having the ground truth (original) co-ordinates of the objects in the image.Now i want to compare the obtained co-ordinates with the…
Ritesh
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OpenCV Python Feature Detection and Matching

I don't understand the feature matching API in FLANN. I found this code and I am using it as a base line for my development: Image stitching Python But I can't figure out what the flann.knnMatch() function is returning. It's a list of tuples of the…
Crbreingan
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How could I detect this object / form the best way?

I am new to image processing and opencv and was wondering what the best way to detect such forms would be: The object can have varying color. Some sort of SURF feature detection, or is there a more simple solution?
madmax
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Problems with OpenCV warpPerspective

I'm working on an Android background subtraction project, with a moving camera. I'm trying to use feature matching, findHomography and warpPerspective to find overlapping pixels between two frames. However, the output I get is slightly incorrect.…
user3019612
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How can you discover what features in a dataset are predictive?

I'm working on a machine learning algorithm for the dataset available here. There are 26 columns of data. Most of it is pointless. How can I effectively and quickly determine what features are interesting - what features tell me one way or another…