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Questions tagged [sift]

Scale-invariant feature transform (SIFT) is an algorithm in computer vision to detect and describe local features in images. This tag is for programming questions related to SIFT implementation or programs that use SIFT algorithm for computer vision applications.

Scale-invariant feature transform (SIFT) is an algorithm in computer vision to detect and describe local features in images, introduced by prof. David Lowe in 2004.

The local features extracted from an image with SIFT can then be used to identify an object from that image. This visualization illustrates homologous SIFT keypoints in two separate pictures of the same magazine cover:

enter image description here

Applications of SIFT include object recognition, robotic mapping and navigation, image stitching, 3D modeling, gesture recognition, video tracking, and match moving.

Algorithm Steps

  • Scale-space extrema detection

  • Keypoint localization

  • Interpolation of nearby data for accurate position

  • Discarding low-contrast keypoints

  • Eliminating edge responses

  • Orientation assignment

  • Keypoint descriptor

More information can be obtained here

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Unable to install opencv's xfeatures2d module from the contrib repository

I'm running opencv-2.4.10 and need to get the xfeatures2d module from the contrib repository. I run the following command: cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D OPENCV_EXTRA_MODULES_PATH=path to contrib/modules -D…
Xstatic
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using SIFT/SURF for feature extraction using opencv on android using Android Studio

I'm working on a feature extraction/matching app using opencv on android using android studio .. I followed these steps for using native code in order to use SIFT or SURF algorithms.. I have copied the folders (armeabi, armeabi-v7a, ...etc) to the…
alaa alzoubi
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How to discretize data (SIFT features)?

My input data looks like [1,1,0,0,0,0,1,0,24,3,0,0,0......] These are SIFT features for images and they are 128 dimensions for each sample likewise I have about 100,000 samples each with 128 dimensions. I want to discretize these features. Is…
Sanathana
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removing commas resolves "IndexError: too many indices for array" but I don't understand results

Sorry if this is some basic stuff, but I can't seem to find any information on this. I'm wondering what the commas do in this situation? f = loadtxt(filename) return f[:,:4],f[:,4:] It's code from Programming Computer Vision and it is throwing up…
Keith Ryan
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Advantages of SIFT over HOG

I am studying SIFT (Scale-invariant feature transform) and HOG (Histogram of Oriented Gradient). So I want to know the advantages of SIFT over HOG in case when we have to extract features from a sequence of frames of an activity (i.e.…
Aadnan Farooq A
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SIFT MATLAB implementation (magnitude value)

would like to know the answer to the following question regarding SIFT if anyone knows. Before I start, I refer you to the implementation of David Lowe's paper through this link: http://www.cs.ubc.ca/~lowe/keypoints/ The function declaration looks…
Aadnan Farooq A
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error while detecting features with SIFT on training set

I have a set of images split in train and test and I'm trying to detect features using SIFT from the train set. The problem is that with my code I'm getting: TypeError: image is not a numpy array, neither a scalar Here's my code: import glob from…
giulia_dnt
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Cannot find the non-free module in Open CV 2.4.8

I am trying to compile my code which uses the SIFT class from the Open CV non free module but without any success. I am using Open CV version 2.4.8. I read somewhere that non free was removed from Open CV in this version and has to be added…
Muhammad Omer
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Using openCV to implement SIFT in image

I have tried to implement SIFT with openCV and I have refer to these links link1 and link2. Besides, I have also read the paper about SIFT written by Lowe. I have some problems about the code in link1 and link2. cv::SiftFeatureDetector detector(…
Kuo
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Image matching and object detection, how to perform detection for small object?

I am using SIFT feature the matching between two images or it can be considered as object detection. First matching. I used SIFT feature for matching and it failed when the object is small. Second matching. However, it woks when I cropped that…
Fiong
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image matching using sift algorithm with global context and local shaped based descriptor

Can anyone explain me how the sift algorithm is working using numerical values..I am searching over Internet but the thing I am getting is only input and output of the sift algorithm but the thing I want that what actually is going on and how,they…
Kavyansh Singh
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Can I use SIFT based descriptors for aerial image classification?

I am working on aerial RGB image classification. Can any expert kindly comment which descriptor would be better for fair classification? Gabor descriptors or SIFT descriptors? Thanks much in advance
user3539646
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Sift Implementation in Vlfeat

I am using the Sift implementation by Vlfeat.org. It has the follwing function which is supposed to save the features to a file. def process_image(imagename,resultname,params="--edge-thresh 10 --peak-thresh 5"): """ process an image and save the…
Erdnase
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CBIR project suggestions

I'm trying to build an CBIR (content based image retrieval) project and for the first step I'm looking at a good feature. This should be invariant on several cues: scale rotation illumination and device, and I've not any database or previous…
user2614596
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Using n- sift code

I want to use N-SIFT (n-dimensional scale invariant feature transform)feature points to detect some spatio-temporal scale invariant regions in a video. I have got the code from the following…
Nilkanta Sahu
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