# \#orb **URL:** https://forum.opencv.org/tag/orb/184.md [Latest](https://forum.opencv.org/latest.md) · [Categories](https://forum.opencv.org/categories.md) · [Tags](https://forum.opencv.org/tags.md) --- ## [How to pass parameters to Flann base matcher using Opencv JS](https://forum.opencv.org/t/how-to-pass-parameters-to-flann-base-matcher-using-opencv-js/21029)
**Author:** [@Borja\_Cano\_Barredo](https://forum.opencv.org/u/Borja_Cano_Barredo)\ **Replies:** 0\ **Last updated:** [May 16, 2025, 8:36am UTC](https://forum.opencv.org/t/how-to-pass-parameters-to-flann-base-matcher-using-opencv-js/21029 "2025-05-16T08:36:29Z")
Hi, After a lot of work trying to make flann matcher and sift to work on OpencvJS i finally have it working. Problem is i am trying to do feature matching for a streaming live cam in real-time and sift and flann are not… --- ## [Why doesn't my mask correctly divide DetectAndCompute into quadrants?](https://forum.opencv.org/t/why-doesnt-my-mask-correctly-divide-detectandcompute-into-quadrants/17907)
**Author:** [@kra2008](https://forum.opencv.org/u/kra2008)\ **Replies:** 5\ **Last updated:** [July 2, 2024, 5:25pm UTC](https://forum.opencv.org/t/why-doesnt-my-mask-correctly-divide-detectandcompute-into-quadrants/17907 "2024-07-02T17:25:54Z")
Ultimately I’m trying to align two photos for stereo viewing by humans. I’m NOT trying to rectify them to help a computer see in 3D. I have several decent methods of getting this done already but I’m trying to explore a … --- ## [Number of keypoints does not match number of descriptors](https://forum.opencv.org/t/number-of-keypoints-does-not-match-number-of-descriptors/17866)
**Author:** [@farhadbat](https://forum.opencv.org/u/farhadbat)\ **Replies:** 1\ **Last updated:** [June 7, 2024, 5:16am UTC](https://forum.opencv.org/t/number-of-keypoints-does-not-match-number-of-descriptors/17866 "2024-06-07T05:16:03Z")
Hi everyone, I have a set of keypoints extracted with an aribirary keypoint detector (orb, random pixel, GFTT, etc). Now, I want to extract ORB descriptor to each keypoint. I used the following code for it; however, nu… --- ## [OpenCV's cornerScore is different from FAST paper](https://forum.opencv.org/t/opencvs-cornerscore-is-different-from-fast-paper/13433)
**Author:** [@ShihanWang](https://forum.opencv.org/u/ShihanWang)\ **Replies:** 1\ **Last updated:** [June 12, 2023, 12:04pm UTC](https://forum.opencv.org/t/opencvs-cornerscore-is-different-from-fast-paper/13433 "2023-06-12T12:04:44Z")
Question About Fast9 Score v is the brightness of center pixel, v\_i is the i-th pixel brightness on circle. OpenCV use this code to calculate Fast9 Score. \\begin{align\*} & D = \\{v - v\_i\\}\_{i\\in\[0,24\]}\\\\ &\\text{for i=0… --- ## [Asynchronous feature detection not running asynchronously](https://forum.opencv.org/t/asynchronous-feature-detection-not-running-asynchronously/10889)
**Author:** [@ChrisN](https://forum.opencv.org/u/ChrisN)\ **Replies:** 3\ **Last updated:** [November 10, 2022, 8:57pm UTC](https://forum.opencv.org/t/asynchronous-feature-detection-not-running-asynchronously/10889 "2022-11-10T20:57:24Z")
I have been experimenting with the asynchronous feature detection calls, but when I time them it seems they still block the CPU for a significant amount of time. I tried to detect ORB features similar to the below: voi… --- ## [How to use computeAsync function with the vector of KeyPoints?](https://forum.opencv.org/t/how-to-use-computeasync-function-with-the-vector-of-keypoints/9408)
**Author:** [@goktugyildirim](https://forum.opencv.org/u/goktugyildirim)\ **Replies:** 0\ **Last updated:** [July 5, 2022, 10:23pm UTC](https://forum.opencv.org/t/how-to-use-computeasync-function-with-the-vector-of-keypoints/9408 "2022-07-05T22:23:13Z")
My aim is to use computeAsync function in order to describe vector of cv::KeyPoint in the host memory because I’m only detecting ORB keypoints and then removing outliers before computing descriptors, but I don’t know ho… --- ## [Not all Feature Points are displayed (with ORB)](https://forum.opencv.org/t/not-all-feature-points-are-displayed-with-orb/9026)
**Author:** [@skrippsta](https://forum.opencv.org/u/skrippsta)\ **Replies:** 0\ **Last updated:** [June 3, 2022, 8:53am UTC](https://forum.opencv.org/t/not-all-feature-points-are-displayed-with-orb/9026 "2022-06-03T08:53:39Z")
I have the problem that not all feature points are displayed in one image. I use the ORB algorithm with OpenCV-JS for the FeaturePoint “detection”. The figure shows my problem: The feature points that are on the edge ar… --- ## [Why does calling ORB\_Impl::detectAndCompute block when using cv::Umat](https://forum.opencv.org/t/why-does-calling-orb-impl-detectandcompute-block-when-using-cv-umat/5917)
**Author:** [@Seng\_Yang](https://forum.opencv.org/u/Seng_Yang)\ **Replies:** 0\ **Last updated:** [October 28, 2021, 4:09am UTC](https://forum.opencv.org/t/why-does-calling-orb-impl-detectandcompute-block-when-using-cv-umat/5917 "2021-10-28T04:09:25Z")
My opencv supports opencl, When I use cv::Mat, ORB::detectAndCompute can be executed normally. However, ORB::detectAndCompute cannot be executed normally when using cv:UMat. my code: UMat img{}; imread(imgName.data(),…