Adding modules from opencv_contrib to OpenCV

Question

I'm trying to add the xfeatures2d module from opencv_contrib to an existing OpenCV/Python project.

I've downloaded the latest version of the module from the repo, and built OpenCV again with the following additional params:

OPENCV_EXTRA_MODULES_PATH=/path/to/opencv_contrib-master/modules
BUILD_opencv_xfeatures2d=ON

Excerpt from build log:

-- Installing: /usr/local/lib/python2.7/site-packages/cv2.so
-- Installing: /usr/local/lib/python3.4/site-packages/cv2.so
-- Installing: /usr/local/lib/libopencv_xfeatures2d.3.0.0.dylib

It appears the new module is installed correctly. I'm able to import cv2 in both Python versions. However neither recognise the new features the module is supposed to add.

>>> cv2.SURF()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'SURF'
>>> cv2.xfeatures2d.SURF()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'xfeatures2d'

Could you consider editing the original Question since the answer does not reflect the question in the title. — Elliot Woods
– Elliot Woods, Commented Mar 2, 2017 at 6:08

Community · Accepted Answer · 2020-06-20 09:12:55Z

17

I encountered this same issue. I'm using python 2.7.6 and OpenCv 3.0 with the additional non-free modules. I do have xfeatures2d present in available modules and can import it, however it was as though xfeatures2d didn't contain SIFT or SURF. No matter how I called them it was the same Error:

"AttributeError: 'module' object has no attribute 'SIFT'

I tried the different name spaces suggested, and only recently noticed this detail and GOT IT WORKING!

$ python

>>>import cv2

>>>help(cv2.xfeatures2d)

You'll notice that it replies that it is now referred to as...

FUNCTIONS
SIFT_create(...)

and

SURF_create(...)

So very simply - the namespace is NOT "cv2.SIFT()" or "cv2.xfeatures2d.SIFT" but rather

cv2.xfeatures2d.SIFT_create()

Please give it a shot!

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jan 26, 2015 at 18:13

Sovtek

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4 Comments

RiggsFolly Over a year ago

This does not really answer the question. If you have a different question, you can ask it by clicking Ask Question. You can also add a bounty to draw more attention to this question once you have enough reputation.

Robbert Over a year ago

Thanks @RiggsFolly, but this could actually, potentially, answer the question.

Robbert Over a year ago

@Sovtek - thanks for submitting your findings! I'll have a look at this solution later this week, when I continue work on the OpenCV project. If it does solve the issue for me, I'll mark your answer as Accepted.

Yonatan Simson Over a year ago

gave you a vote for the help(cv2.xfeatures2d). Worked for me.

gtzinos · Accepted Answer · 2018-01-20 10:46:31Z

7

Install it from pip

Python 2.x

pip install opencv-contrib-python

Python 3.x

pip3 install opencv-contrib-python

Use sudo if a permsision error occurred.

answered Jan 20, 2018 at 10:46

gtzinos

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2 Comments

mapto Over a year ago

I cannot find this package. Also 'pip3 list | grep opencv' does not contain it. Any ideas what am I missing?

mapto Over a year ago

Actually, found it, not sure why it failed the first time.

Jprog · Accepted Answer · 2015-01-12 22:33:17Z

4

Another possibility (and the easiest one I found!) is to install the 2.4.9 release which already include SIFT and SURF algorithm. You just have to do then

import cv2
sift = cv2.SIFT()
(...)

answered Jan 12, 2015 at 22:33

Jprog

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1 Comment

Robbert Over a year ago

Thanks for chiming in Jprog. I did end up using 2.4 for now (2.4.10 actually). I won't mark this as an accepted answer though, as it does not solve the issue in OpenCV 3.

berak · Accepted Answer · 2014-09-26 12:10:06Z

2

you are missing the new, additional namespace:

>>> help(cv2.xfeatures2d)
Help on module cv2.xfeatures2d in cv2:

NAME
    cv2.xfeatures2d

FILE
    (built-in)

FUNCTIONS
    SIFT(...)
        SIFT([, nfeatures[, nOctaveLayers[, contrastThreshold[, edgeThreshold[,
sigma]]]]]) -> <xfeatures2d_SIFT object>

    SURF(...)
        SURF([hessianThreshold[, nOctaves[, nOctaveLayers[, extended[, upright]]
]]]) -> <xfeatures2d_SURF object>

    StarDetector(...)
        StarDetector([, _maxSize[, _responseThreshold[, _lineThresholdProjected[
, _lineThresholdBinarized[, _suppressNonmaxSize]]]]]) -> <xfeatures2d_StarDetect
or object>

DATA
    FREAK_NB_ORIENPAIRS = 45
    FREAK_NB_PAIRS = 512
    FREAK_NB_SCALES = 64


>>> surf = cv2.xfeatures2d.SURF(300)

answered Sep 26, 2014 at 12:10

berak

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8 Comments

Robbert Over a year ago

Thanks @berak (you seem to answer all OpenCV questions I come across). I have tried xfeatures2d but it gives the same error - no such attribute - on both Python 2 and 3. It also doesn't explain why PyCharm is autocompleting correctly.

berak Over a year ago

can it be, you got 2 pythons in your box ?

Robbert Over a year ago

Correct, I have both Python 2.7 and 3.4, just to test which version works, since OpenCV 3 is still in alpha. Both are able to load OpenCV correctly (though I have to change EXPORTPATH accordingly) and call regular cv2 properties.

Robbert Over a year ago

PyCharm was probably picking up autocomplete from an older OpenCV installation, considering the new namespace in OpenCV 3. When I reload the modules in PyCharm, autocomplete no longer works.

Fake Name Over a year ago

I've been dealing with this issue myself. It looks like xfeatures2d is flat-out broken in the alpha/beta releases. It's building properly (at least according to the build log), but the python API is not built at all.

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