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Questions tagged [surf]

Speeded-Up Robust Features (SURF) is a feature detection algorithm used in many [tag:computer-vision] tasks, such as object recognition, 3D reconstruction, camera calibration, and [tag:cbir].

Speeded-Up Robust Features (SURF) is an algorithm in computer vision to detect and describe local features in images.

SURF is billed as specifically “Speeded-Up” and “Robust” over its predecessor, the SIFT algorithm – it is based on Hessian blob detection, and eschews the more byzantine arrangements of SIFT (e.g. octaves). This visualization illustrates SURF features with circles, scaled accordingly for each feature, overlaid on the image from which they were extracted:

SURF feature overlaid

The standard standard SURF implementation, from the introductory journal article, is about an order of magnitude faster than David Lowe’s implementation of SIFT (when run in a comparable environment).

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OpenCV C++ Bag Of Words

Everywhere online, you can find little tutorials on different segments of a BOW, but (from I've found anyway) nothing on what you do after: bowDE.setVocabulary(dictionary); ... bowDE.compute(image, keypoints, descriptors); Once you've used the…
fakeaccount
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Unable to use SurfFeatureDetector in OpenCV 3.0.0

System- Windows 8.1 64 bit machine OpenCV 3.0.0 Visual Studio 12 2013 I have built the openCV 3.0.0 with the contrib modules. However, when I compile this code I get errors. #include //used for taking in input from…
Chaitanya Uttarwar
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OpenCV banner matching during sports events

I want to match commercial banners on images during sports events on the walls of arenas. I used this example. If the image is large enough its working quite good (scene_1). But if there is some kind of distortion, or the picture is smaller than…
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Integral Image border handling

I have an Integral Image which I computed from a normal gray Image. I checked it and it look like this one: Now I apply some Box Filters on the Integral Image, for example the Box Filters which are used in SURF. My Problem now is that the Filter…
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Matlab SURF points to pixel coordinates

I want to extract (x,y) pixel coordinates out of the SURF points returned, as an example in the example provided here using Matlab. It is clear that using 'ptsIn(1).Location' I can return the (x,y) coordinates of the point. But the points retuned…
Huá dé ní 華得尼
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OpenCV - Surf Algorithm - Giving lots of false positives

I am learning OpenCV and have started exploring the SURF Algorithm for image matching. I have created a sample image library by modifying the default images available with Microsoft Windows 7. Each image has a rotated, scaled, blurred and skewed…
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Measure of accuracy in pattern recognition using SURF in OpenCV

I’m currently working on pattern recognition using SURF in OpenCV. What do I have so far: I’ve written a program in C# where I can select a source-image and a template which I want to find. After that I transfer both pictures into a C++-dll where…
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Train KNN classifier with several samples OpenCV Python

I am working on a logo classifier/recognizer using Python 2.7.5 and OpenCV 2.4.8, I have several images of the same logo but in different forms and presentations, I would like to train the classifier with that information and at the final recover…
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OpenCV saving image, keypoints and descriptors to file

I'm using SURF/FLANN detector and I'm looking to save the image, points, descriptors to a file so I can then compare this image and it's points to a second image and points however I'm getting the following error when I try to write: In file…
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How to apply box filter on integral image? (SURF)

Assuming that I have a grayscale (8-bit) image and assume that I have an integral image created from that same image. Image resolution is 720x576. According to SURF algorithm, each octave is composed of 4 box filters, which are defined by the number…
user1090249
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Bag of Visual Words in Opencv

I am using BOW in opencv for clustering the features of variable size. However one thing is not clear from the documentation of the opencv and also i am unable to find the reason for this question: assume: dictionary size = 100. I use surf to…
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Why we use SURF descriptors?

I just studied about SURF and going for its implementation , but i still didn't get why we use descriptor in it , i understand about keypoints in it , their purpose , but when we extract the keypoints than why we need to go for descriptors ? and…
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Opencv Feature vector size of SiFT

I am trying to use sift for object classification using Normal Bayes Classifier.When I compute the descriptors for each image of variable size i get different sized feature vectors. Eg: Feature Size: [128 x 39] Feature Size: [128 x 54] Feature…
rish
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OpenCV object (stamp) recognition/detection

Good day! Just sorry for my English. There are a few samples (etalons) stamps of various companies. And there are test images - photos of documents on which these stamps can occur. It is necessary to determine whether there is in the picture with…
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opencv and python: how to use cv2.surf() with mask

I am a newbie at opencv and python and am trying to collect keypoints and descriptors of faces within an image. I am using HAAR cascade classifier with frontal face template to look for faces in an image. The HAAR cascade gives me a list of…
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