Non-free feature detectors in 3.0

answered 2014-10-12 06:55:25 -0600

berak
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updated 2014-10-23 03:54:08 -0600

in 3.0, SIFT and SURF were moved to the opencv_contrib repo

you will need to clone/fork/download that, and add that to your cmake;

cmake -DOPENCV_EXTRA_MODULES_PATH=<opencv_contrib>/modules

then, after building,

#include "opencv2/xfeatures2d/nonfree.hpp"

if you want to use SIFT/SURF directly, it's

[EDIT: latest refactoring removed a lot of possibilities. you can't create a'stack' object anymore, also, the 'factory functions'(Algorithm) are gone. ]

~~xfeatures2d::SURF surf;~~

Ptr<xfeatures2d::SURF> surf = xfeatures2d::SURF::create();

~~if you want the factory functions:~~

~~xfeatures2d::initModule_xfeatures2d(); // note additional namespace Ptr<FeatureDetector> sift = FeatureDetector::create("SIFT");~~

last, you will have to link against opencv_xfeatures2d.

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I've done all the building, but it's the factory bit that doesn't work. In 2.x, you call cv::initModule_nonfree(); to initialise, but that is missing in 3.0 and the call to FeatureDetector::create() fails for nonfree descriptors.

CraigH ( 2014-10-12 07:44:16 -0600 )edit

Ok, so now I'm missing the library for cv::features2d::SIFT, and get unresolved externals. Which library should it be in?

CraigH ( 2014-10-12 09:23:51 -0600 )edit

you will have to link opencv_xfeatures2d, sorry for not mentioning this before ;)

again, it seems safer atm, to create an instance directly, like

xfeatures2d::SURF surf2;

cerr << surf2.name() << endl;

berak ( 2014-10-12 09:27:04 -0600 )edit

Hmm, i must be building it wrong. I don't have an xfeatures2d lib :(

CraigH ( 2014-10-12 09:46:41 -0600 )edit

look at the cmake output, if it was enabled or not.(or why)

older versions had xfeatures2d disabled by cudaarithm dependancy , maybe you want to update the whole schlepp.

berak ( 2014-10-12 09:58:05 -0600 )edit

I pulled the latest from git, both opencv and opencv_contrib and with your extra line, it all now works. Thanks for all your help!

CraigH ( 2014-10-12 10:21:30 -0600 )edit

@berak: guess, initModule_xfeatures2d() solves that issue

Guanta ( 2014-10-12 10:43:38 -0600 )edit

xfeatures2d::initModule_xfeatures2d(); thanks, @Guanta

berak ( 2014-10-12 10:59:43 -0600 )edit

Hi all: old style : Ptr<SIFT> sift=new SIFT(nfeatures,nOctaveLayers,contrastThreshold,edgeThreshold,sigma) But in OpenCV3.0: How to set up those params?

wuling ( 2014-10-14 02:52:01 -0600 )edit

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