Stack Overflow
Stack Overflow

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.

187 questions
2
votes
1 answer

OpenCV connection between keypoint size and octave

I am working with OpenCV keypoints and I got a questions about keyPoint size and octave. I know that a keyPoint have a coordinate (x,y) and size which simply can be described as a circle with (x,y) center and radius of size. And I know that there…
mbaros
  • 825
  • 8
  • 31
2
votes
1 answer

Modification of the Dense algorithm in OpenCV

I'm using Dense algorithm implementation in OpenCV. Version 2.4.x I would like to know if there is an option to modify the feature detection so that not each pixel is looked on but maybe each 5th. Doing that i can reduce the data and speed up the…
Jürgen K.
  • 3,427
  • 9
  • 30
  • 66
2
votes
1 answer

opencv c++ mat to vector

After searching for an answer to this (1, 2, 3, 4) I am still confused on both If this is possible and, if so, how to do it I want to be able to read from an .xml file which has had a cv::Mat containing Point2f keypoints written to it, reading it…
MLMLTL
  • 1,519
  • 5
  • 21
  • 35
2
votes
2 answers

relationship between SIFT keypoint orientation and SIFT description orientation

I am using VLfeat open source for extracting SIFT keypoints and their descriptions. The image below shows one of them. The yellow disc indicates the keypoint's scale (radius) and orientation (line). The green frame indicates its description (i.e.,…
YW P Kwon
  • 2,138
  • 5
  • 23
  • 39
2
votes
1 answer

OpenCV Keypoints response, greater or less?

According to OpenCV KeyPoint documentation, there is response field in every keypoints that: float response: The response, by which the strongest keypoints have been selected. But I couldn't find whether the greater response is better or less? I…
Mikael S.
  • 1,005
  • 3
  • 14
  • 28
2
votes
3 answers

Can i specify the FAST keypoints number i get when using opencv FastFeatureDetector

i am using openCV FastFeatureDetector to extract fast keypoints from image. but the number of the FastFeatureDetector detect is not a const number. i want set the max keypoints number FastFeatureDetector get. Can i specify the FAST key points…
Moore liu
  • 31
  • 1
  • 8
1
vote
0 answers

OpenCV Python Stitching: Define custom keypoints / matches skipping feature detector & matcher

I'm trying to implement the panorama stitching via OpenCV into our process, but want to use control points / matches gathered from PTGui. PTGui however just lists the keypoints and the matches between images, no angles or additional data. When using…
k.m.
  • 41
  • 2
1
vote
0 answers

In detectron2, how could I put the keypoint names on the image?

First, I will explain the problem statement. I am wuing Detectron2 for keypoint detection for my custom dataset. I am using the below code to visualize the bounding box and the keyoints. outputs = predictor(im[..., ::-1]) v = Visualizer(im[:, :,…
Amit
  • 51
  • 5
1
vote
0 answers

How to train custom keypoint detection with COCO formated dataset and Detectron2 with out skeleton?

I have successfully trained a model for custom instance segmentation using Detectron2. Now I am preparing my custom dataset to train a keypoint detection model using Detectron2. Detectron2 uses COCO formatted dataset for training. The format of COCO…
Amit
  • 51
  • 5
1
vote
1 answer

applying MSDDetector in colab

I have trouble writing the MSD detector correctly. However, it has no attribute ''create''. I wrote the following code. But my session crashed for an unknown reason. msd=cv2.xfeatures2d.MSDDetector() kps1=msd.detect(I1) I will appreciate any help.
Negar Jovhari
  • 11
  • 2
1
vote
1 answer

OpenCV SIFT+FLANN multiple matches for single keypoint

I'm trying to match keypoints using open cv. Specifically, I'm using the "sift" detector and "flann" matcher. My code is based on cv2's documentation: detector = cv2.SIFT_create() matcher = cv2.FlannBasedMatcher(indexParams=dict(algorithm=0,…
Jon Nir
  • 507
  • 3
  • 15
1
vote
0 answers

Find homography for stitching

I’m working on the following task: I have 6 fisheye cameras and would like to produce a 360 degree stitched image. After carrying out the calibration procedure with findChessboardCorners, calibrateCamera, I obtained the intrinsic and extrinsic…
compup
  • 77
  • 1
  • 8
1
vote
0 answers

How do I re-train Torchvision's keypoint R-CNN with a custom COCO-style dataset?

I've created a custom COCO keypoints style dataset using COCO annotator and want to retrain Torchvision's Keypoint R-CNN on it. I'm trying to use torchvision's CocoDetection dataset class to load the data, and I had to rewrite the _load_image method…
Sam Middleton
  • 11
  • 2
1
vote
1 answer

Finding keypoints in an handwritten arrow

I have been trying to find two keypoints (head and tail) in arrows I have drawn, I was wondering is there a simpler approach than training a CNN, such as a using a classic approach (opencv). I have used this simple approach: bi =…
JammingThebBits
  • 732
  • 11
  • 31
1
vote
1 answer

Extract pixel values from an image for CV2.Keypoints objects

I have a tuple (Keypoints, Descriptors) extracted from img1 using the method: (kp, des) = sift.detectAndCompute(img1,None) kp is a list containing cv2.KeyPoint objects, and des is a numpy.array containing their 128 dimensional descriptors I want to…
Yahya ZEFRI
  • 13
  • 3
1 2 3
…
12 13