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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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How to find descriptors for manualy defined landmarks with opencv

I am trying to generate "SIFT" descriptor (SIFT is only an example) for some manualy defined landmarks. When I try to do: siftDetector(grayImage, Mat(), manualLandmarks, descriptors, true); the result is always 0 (zero) for the descriptors. I have…
goe
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In C, given an image containing numbers, how do I extract each individual number into a separate image?

As an example. Suppose an image contains the number 1 and 2 in black. The background is white. I want to end up with two new files where one contains just the number 1 and the other contains just the number 2. I have been playing around with Sift in…
chillbabe104
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OpenCV SIFT key points extraction isuue

I tried to extract SIFT key points. It is working fine for a sample image I downloaded (height 400px width 247px horizontal and vertical resolutions 300dpi). Below image shows the extracted points. Then I tried to apply the same code to a image…
Grant
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NullPointerException in javacv

i am trying to extract SIFT features from an image using JavaCV and OpenCV here is my code import java.io.File; import com.googlecode.javacv.cpp.opencv_core.CvMat; import com.googlecode.javacv.cpp.opencv_features2d.DescriptorExtractor; import…
user3249214
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Can SIFT run in realtime?

Is there any C/C++ implementation of SIFT that runs in realtime in a processor of ~2.2GHz and a RAM of 4GB? Or what is the lowest achievable runtime for extracting SIFT features and descriptors of ~2000 keypoints. The C++ implementation by Andrew…
Ankit Nayan
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how to do k means clustering on sift features in matlab?

I want to perform k-means clustering on sift features which is in the form of a 509X508 matrix.I got a code for k-means clustering from mathworks. But i don't know how to give input for the algorithm. Pls help...
user3627439
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OutOfMemoryError opencv (NON 64bit solution needed)

Hey guys I have an issue with my opencv 2.3.0 All I am trying to do is extract SIFT features from an image I have downloaded. Now the image is very large (around 120MB) 6124w X 7636h PNG and the error I see is: OpenCV Error: Insufficient memory…
Jay
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Can Hadoop reduce runtime of SIFT?

Can we use hadoop to run SIFT on multiple images? SIFT takes ~ 1s on each image to extract keypoints and its descriptors. Considering that each run is independent of others and runtime of 1 run cannot be reduced, can we reduce runtime…
Ankit Nayan
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unknown command line flag 'logtostderr'

I am running this SIFT program at this site: https://github.com/sanchom/sjm All the stuffs go well until I run my program: $ python extract_caltech.py --dataset_path=[path_to_your_101_Categories_directory] \ --process_limit [num_processes_to_spawn]…
Phong Nguyen
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Compute sift at custom key points

I want to find the sift descriptors at custom Keypoint locations in matlab. Is there any function in vlfeat library to do so ?
Deepesh
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/bin/sh: extract_descriptors_cli: command not found

I am running the source code of Local Naive Bayer Nearest Neighbor form this site : https://github.com/sanchom/sjm i extract SIFT descriptor of the dataset Caltech 101 by running: python extract_caltech.py --dataset_path…
Phong Nguyen
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How to draw keypoints onto input image using matlab?

This question is regarding SIFT features and its use in MATLAB. I have some data containing the following information: The x,y co-ordinates of each feature point The scale at each feature point The orientation at each feature point The descriptor…
user3168226
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OpenCV 2.4.6 linker error LNK2001

I am trying to run the opencv surf implementation here in VS 2013. I've already arranged the libraries in Linker->Input for example opencv_core246.lib for release and opencv_core246d.lib for debug. But when I try to run the program, I getting the…
user997248
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OpenCL same code different results: 1.Nvidia760 2.Nvidia560 3.Vivante

I use OpenCL for image processing(About SIFT algorithm specially). Actually, I tested the same code using two images with different sizes. One is 1024*768, the other is 512*384. My opencl GPU platform are 1. NvidIA 760(PC, 2G) 2. Nvidia 560(PC, 1G)…
David Ding
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opencv SIFT/SURF: output best match from one to many comparison

Im using the matching to many images sample with opencv here's original version Im struggling to understand the code, I'm simply looking to calculate and output the image that has the most/best matches. What I thought was I could use for…
user3061694
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