sift

How to get a rectangle around the target object using the features extracted by SIFT in OpenCV

由 微笑、不失礼 提交于 2019-12-05 19:15:36
问题 I'm doing project in OpenCV on object detection which consists of matching the object in template image with the reference image. Using SIFT algorithm the features get acurately detected and matched but I want a rectagle around the matched features My algorithm uses the KD-Tree est ean First technique to get the matches 回答1: If you want a rectangle around the detected object, here you have code example with exactly that. You just need to draw a rectangle around the homography H. Hope it helps

Detecting outliers in SURF or SIFT algorithm with OpenCV

由 你说的曾经没有我的故事 提交于 2019-12-05 18:44:15
Which method is the best to compare two images and discard outliers points? In find_obj.cpp opencv example, they use FLANN, but don't discard outliers. I have seen some methods like using Kmeans or graphs. There is a fairly reliable and efficient way to both reject noisy points and determine the transformation between your points of interest. The algorithm that is usually used to reject outliers is known as RANSAC (http://en.wikipedia.org/wiki/RANSAC), and the algorithm used to determine the transformation can take several forms, but the most current state of the art is known as the five-point

How does the Lowe's ratio test work?

由 瘦欲@ 提交于 2019-12-05 12:45:42
Suppose I have a set of N images and I have already computed the SIFT descriptors of each image. I know would like to compute the matches between the different features. I have heard that a common approach is the Lowe's ratio test but I cannot understand how it works. Can someone explain it to me? Hamed Etezadi For better understanding the ratio test, you need to read his article. Only by reading the article you will find out your answer. The simple answer is that it is low, which Lowe achieved during his experiments and suggest that for choosing between two similar distance, choose the one

OpenCV Python Feature Detection: how to provide a mask? (SIFT)

由 可紊 提交于 2019-12-05 11:33:01
I am building a simple project in Python3, using OpenCV3, trying to match jigsaw pieces to the "finished" jigsaw image. I have started my tests by using SIFT. I can extract the contour of the jigsaw piece and crop the image but since most of the high frequencies reside, of course, around the piece (where the piece ends and the floor starts), I want to pass a mask to the SIFT detectAndCompute() method, thus forcing the algorithm to look for the keypoints only within the piece. test_mask = np.ones(img1.shape, np.uint8) kp1, des1 = sift.detectAndCompute(img1, mask = test_mask) After passing a

need advise on sift feature - is there such thing as a good feature?

由 人盡茶涼 提交于 2019-12-05 08:12:05
问题 I am trying out vlfeat, got huge amount of features from an image database, and I am testing with the ground truth for mean average precision (MAp). Overall, I got roughly 40%. I see that some of the papers got higher MAp, while using techniques very similar to mine; the standard bag of word. I am currently looking for an answer for obtaining higher MAp for the standard bag of word technique. While I see that there are other implementation such as SURF and what not, let's stick to the

Asift and openCV?

由 狂风中的少年 提交于 2019-12-05 03:34:39
问题 Does opencv allows to use ASIFT ? http://www.ipol.im/pub/algo/my_affine_sift/ The creator published the c++ so I believe it wouldn't be so hard to implement it into opencv 回答1: What do you mean by Does opencv allows to use ASIFT ? At this moment, ASIFT is not available in OpenCV directly, but it should be a no-brainer to connect the code provided by the ASIFT authors to OpenCV. Probably all you'll have to do is to convert the OpenCV cv::Mat to some specific image format, by accessing Mat:

OpenCV 2.4.6 SIFT KeyPoints Detection using a lot of memory

由 与世无争的帅哥 提交于 2019-12-05 02:24:27
问题 We were using SIFT in openCV 2.4.3 and we decided to upgrade to openCV 2.4.6. After the upgrade, the memory usage jumped from about (150MB) to 1.2GB in openCV 2.4.6. Does someone knows if is this a bug or something that we need to configure now? Our image has 1.4MB. This behavior was observed on iOS. The problem seems to be happening also in Linux (CentOs). Tks 回答1: I remember there was a bug in one of those versions regarding keypoint extraction. I saw it with ORB, so I don't know if it is

SIFT implementation in MATLAB Tutorial

由 假如想象 提交于 2019-12-05 02:16:39
问题 I'm looking for some basic SIFT implementation in MATLAB. I need to write it from first principles. Also, I'm looking for something which explains whats going on in the program. Vedali's code and David Lowe's code just go over my head. 回答1: If you are a Matlab user, you must know this excelent site web : Matlab File Exchange There, you will find the following project : Feature Points In Image I think this project will fully answer to all your questions about sift. It also posible to have a

SIFT is not finding any features in reference image in OpenCV

由 牧云@^-^@ 提交于 2019-12-04 23:09:54
问题 I have an image of the target logo that I am trying to use to find target logos in other images. I am currently running two different detection algorithms to help me detect any logos on the image. The first detection I use is Histogram based in which I search the image for a general area on screen where the colors are very similar. From there I run SIFT to further get the object that I am looking for. This works on most logos however the Target logo that I have isn't even picking up and

Opencv 3.0 - module object has no attribute 'xfeatures2d'

由 五迷三道 提交于 2019-12-04 22:16:29
I have shifted from OpenCV 2.4.9 to 3.0 to make use of drawMatches and drawMatchesKnn function. I came to know that it does not come along with non-free algorithms like SIFT , SURF. So I installed opencv_contrib from https://github.com/Itseez/opencv_contrib by following steps cmake -DOPENCV_EXTRA_MODULES_PATH=/home/zealous/Downloads/opencv_contrib-master/modules /usr/local .. make -j5 make install I also cross checked in modules of opencv , xfeatures2d was there. Then when I tried to do >>> import cv2 >>> help(cv2.xfeatures2d) It gives me following error Traceback (most recent call last): File
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