Questions tagged [local-features]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
2
votes
1answer
5k views

Zernike Moments' implementation in OpenCV

The reason why Hu moments were implemented in OpenCV and why Zernike moments were not implemented is looking like their performance similar as stated in this paper. As stated in the paper Zernike ...
2
votes
0answers
2k views

MPEG-7 descriptors' implementation in OpenCV

I'm looking for implementation of MPEG-7 descriptors which are compatible with OpenCV's recent versions and containing "region-based shape descriptor ART(Angular Radial Transformation)". I ...
2
votes
1answer
233 views

Can SIFT run in realtime?

What is the best possible runtime for extracting SIFT keypoints and Descriptors? I know it depends on #keypoints extracted. So, say for image of size 640x640, the code that I have been using requires ...
0
votes
1answer
77 views

need general resource about image matching

i'm working on image matching mainly SIFT and SURF for my thesis. i read Moravec's and harris corner detectors and understand them quiet well in my own opinion.A COMBINED CORNER AND EDGE DETECTOR[1] ...
0
votes
1answer
339 views

Phase reference of a periodic signal

Assume an arbitrary (discrete) signal that is periodic and known over a whole period. I need a way to select a characteristic point along the signal such that I can always retrieve it even when the ...
1
vote
1answer
657 views

Feature for exact matching of images

I am trying to match images from a large dataset which exactly match the given input image.(images with deformations/transformations are treated as different) I have tried euclidean distance but it ...
15
votes
1answer
5k views

Binary robust independent elementary features ("BRIEF") understanding

How are the descriptors in the BRIEF algorithm matched to each other? How is the template image found in the another image? How do we compare the descriptors? I have read that article but didn't ...
3
votes
2answers
3k views

Methods to quantify randomness (or complexity) in a signal

What are the methods through which we can quantify the randomness or complexity in a given signal. I know spectral flatness measure (geometric to arithmetic means) is one way to do it, but what are ...
4
votes
2answers
182 views

mean of wavelet for image processing

For many papers which talks about using wavelet transforms for feature detection in image processing, it is stated that it is advantageous for the wavelet to have zero mean? Why is this so? Thanks in ...
2
votes
1answer
100 views

What is localizability in Computer Vision?

Please consider the following excerpt (from Rodrigo R, Zouqi M, Chen Z, Samarabandu J.: Robust and efficient feature tracking for indoor navigation): Robust feature tracking is a requirement for ...
3
votes
1answer
699 views

proving that a log gabor filter has 0 DC offset

I have read somewhere online that the log gabor filter has an advantage over the gabor filter, in the sense that it has 0 DC component. How do you prove this property mathematically? Thanks in advance....
8
votes
3answers
3k views

Purpose of image feature detection and matching

I'm a new guy in image processing and computer vision, so this question might be stupid to you. I just learned some feature detection and description algorithms, such as Harris, Hessian, SIFT, SURF, ...
8
votes
4answers
1k views

Preprocessing to improve Harris corner tracking between video frames?

In our unmanned aerial vehicle grayscale video image stabilization application, we're having difficulty finding the "good" Harris corners in frame N+1 selected from frame N. The source of the ...
0
votes
0answers
1k views

HOG descriptor algorithm

I would like to implement a HOG descriptor in C++. I found an implementation of this code here. An extract of the code follows: ...
2
votes
1answer
107 views

feature detectors and descriptors comparison

There are several kinds of detectors and descriptors, like SIFT, SURF, FAST. I wonder are they all eligible for real-time applications? Which is the best or better? ...
3
votes
1answer
1k views

Determining false positives in feature matching

I extracted features from an image using SIFT and SURF. Then I applied few transforms on the image and again calculated the features. While matching the features, I noticed that there are some ...
2
votes
1answer
7k views

blob detection using Laplacian of Gaussian filter

I'm learning feature-detectors from this lecture notes, and I don't quite understand the Normalized Laplacian of Gaussian ...
2
votes
0answers
179 views

Affine detector + SIFT descriptor

I am approaching to the Oxford Buildings dataset which contains already computed SIFT descriptors from affine detected keypoint locations. Usually SIFT detector provides to its detected keypoints ...
4
votes
3answers
747 views

Local Image Features Extraction for Road Signs

I'm working on a project to detect a road sign from the Image. Consider the sample image below: I'm using a heuristic search to detect the road sign within an image. Basically, I want some weak ...
5
votes
0answers
145 views

Filtering Corners Detected on Multiple Scales

I made a multi-scale Harris corner detector (inspired by MOPS) which is simply a Harris corner detector performed on several scales (i.e. subsampled versions of the same image). This effectively make ...
2
votes
1answer
2k views

Understanding Integration Scale in Multi-Scale Harris Corner Detector

I would like to improve a simple Harris corner detector by adding more scales. I don't need scale-invariant interest points, just to detect more points by processing more scales. The Wikipedia says ...
0
votes
1answer
322 views

best robust feature detectors for detecting similarities among archeological signs

I would like to implement edge detectors for creating a feature vector for archeological signs. Which are best features, algorithms to retrieve? That could be loaded in a Support vector machine for ...
2
votes
2answers
3k views

A feature extraction method: Principal Component Analysis (PCA)

I read some articles about PCA and I think the nice way to summarize it is: It is a way of identifying patterns in data, and expressing the data in such a way as to highlight their similarities and ...
9
votes
2answers
1k views

Image Processing Prior to Feature Detection

I have implemented a feature detector based on Harris corners. It works fine most times, but there are cases where it performs poorly. I need to make it work on many different images without ...
15
votes
2answers
1k views

Image Registration by Segmentation

Image registration algorithms are usually based on point features such as SIFT (Scale-Invariant Feature Transform). I saw some references to line features, but I was wondering if it would be possible ...
4
votes
1answer
201 views

What scale should a detected SIFT point be extracted at?

I've heard this from a few different researchers but I can't find a definitive value. Given the "scale" extracted by David Lowe's SIFT detector, we need to extract a descriptor at a specific scale. ...
15
votes
1answer
4k views

Detection of circles (ellipses) in 2D point cloud

Given a set of points (2D) i.e., point cloud (PC), the question is about a robust, accurate and ...
9
votes
1answer
2k views

Good features / algorithms for recognizing car-models in images

I have a question concerning object recognition, especially recognizing car-models! I am at the beginning of a work about identifying the same car-model in different images. At the moment I think one ...
5
votes
1answer
629 views

Patent-free Interest Point Detector? [duplicate]

Possible Duplicate: Free alternatives to SIFT/SURF for commercial use There are same very good algorithms for interest point detection/description, like: SIFT (Scale-Invariant Feature Transform) ...
5
votes
1answer
403 views

image feature extraction

We are given a set of grayscale image patches obtained from images after edge detection. Each patch is 10x10 pixels with intensity varying between 0 and 255 for each pixel. This set may contain a very ...

1
2