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Questions tagged [keypoint]

In computer vision field a keypoint is an interest point detected by the SIFT algorithm. Use this tag for programming issues related to the use of keypoints in the field of computer vision.

is an algorithm that finds "keypoints" in images that are robust to scale variations, perspective and lighting. In order to identify those keypoints, descriptors are generated basing on the surrounding pixels of the keypoint. This way, the same keypoints can be located in different images, which is called matching.

Programing questions related to keypoints in computer vision applications are an appropriate field for this tag.

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What model is needed to detect facemark by using OpenCV_Contrib?

I'm trying to detect the landmarks of human face by using OpenCV_Contrib. However, there are some problems to detect face landmarks. I received one answer that I need to use…
Hsmlee
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OpenCV FAST - too many features

I'm trying to extract features so I can later train a SVM which will be used in Android app. I'm using python to find and extract the features because it is easy to write and saves time. My problem is that I get too many features and I don't know…
dephinera
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Optical flow vs keypoint matching: what are the differences?

I've spent some months studying and making experiments with the process of keypoint detection, description and matching. In the last period, I'm also into the concepts behind augmented reality, precisely the "markerless" recognition and pose…
TheUnexpected
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Keypoint recognition as classification?

At the end of the introduction to this instructive kaggle competition, they state that the methods used in "Viola and Jones' seminal paper works quite well". However, that paper describes a system for binary facial recognition, and the problem being…
mavix
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OpenCV descriptor removes keypoint

OpenCV 2.4 has detector and descriptor. I am creating keypoints for a lot of images and the problem is that the detector gets the keypoints but the descriptor sometimes removes them all. How do I disable the descriptor from removing the points? Is…
Han
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How to make my own feature detection method in opencv?

Let's take a look on this basic tutorial named Features2D + Homography to find a known object. It uses SurfFeatureDetector to detect features: SurfFeatureDetector detector( minHessian ); std::vector keypoints_object, keypoints_scene; …
fen1ksss
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OpenCV SURF keypoints Comparison

I have 2 image with a little bit orientation to left in camera, i want to find the orientation from opencv, i get surf keypoints from 2 image and my problem is how to compare this 2 keypoints to find orientation.
Mahyar
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SimpleCV side by side view and sift features

Since I'm a beginner to SimpleCV, can somebody please guide me with the following application: The thing is that I'm working on a stereo project. I have two images, from left and right eyes. First: I must display them side by side. (After using…
dramaticlook
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How can I avoid getting overlapping keypoints during inference?

I have been using Detectron2 for recognizing 4 keypoints on each image, My dummy dataset consists of 1000 images, and I applied augmentations. def build_train_loader(cls, cfg): augs = [ T.RandomFlip(prob=0.5,horizontal=True), …
JammingThebBits
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Fine tuning Object Keypoint Similarity (OKS)

I have been trying to figure out how to compute the object similarity (OKS) in Detectron2, In my custom dataset I have 4 keypoints per image, I'd like during training to improve the Object Keypoint Similarity's score properly, therefore I need to…
JammingThebBits
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Load coco keypoints dataset in tensorflow

How can I load coco keypoints dataset (image and keypoint annotations) in tensorflow using tf.data.Dataset? There's a coco Dataset in tensorflow but it's only for object detection. Regards.
Nick Skywalker
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How to vectorize a nested for loop in which the second loop is dependent on the first loop in Python?

I am new to using NumPy, my knowledge of Python is limited and also new to working on images. I don't understand how to do this. I need to know how to vectorize a nested for loop in Python in which the second loop in dependant on the first loop.…
Tuhin
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OpenCV FAST TYPE_5_8

I am experimenting with different types of OpenCV's FAST detector. Available types are: TYPE_5_8, TYPE_7_12, TYPE_9_16 The last one is the default and is described by this photo: I assume TYPE_7_12 means the following: And the TYPE_5_8 means…
AndroC
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How to get keypoint "within the homography"?

Referring to this answer to this question: What is happening is that you're considering all the keypoints detected in the second image for the calculation of repeatability and actually only the keypoints within the homography should be used. I…
justHelloWorld
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opencv c++ compare keypoint locations in different images

When comparing 2 images via feature extraction, how do you compare keypoint distances so to disregard those that are obviously incorrect? I've found when comparing similar images against each other, most of the time it can fairly accurate, but other…
fakeaccount
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