Thanks Cedric,
Upon some further inquiry, I agree.
I do not think it is the `outImg` argument that is the problem, `nothing`
worked just fine for another OpenCV function that had `None` written as a
Python equivalent, as did the arguments for kp1, kp2, and the train and
query images. The only thing left is good[] array, which was frankly a bit
more difficult to work with because of the PyCall conversion between
Python's nested lists and Julia's Abstract Arrays.
In short, I changed this Python piece:
good[] is of type `list`
good = []
for m,n in matches:
if m.distance < 0.75*n.distance:
good.append([m])
To this in Julia:
good[] is of type `Array{Any,1}`
good = []
for i=1:size(matches,1)
if matches[i,1][:distance] < 0.75*matches[i,2][:distance]
push!(good, matches[i,1])
end
end
To anyone, does it look like this could have caused a problem?
Thank you
On Friday, June 17, 2016 at 2:42:32 PM UTC-4, I Ce wrote:
>
> I am using PyCalland @pyimport cv2 to implement an OpenCV
> feature-matching program in Julia.
>
>
> I have an example of the code I want to use in *Python* (see *Brute-Force
> Matching with SIFT Descriptors and Ratio Test* in this link:
> http://docs.opencv.org/3.0-beta/doc/py_tutorials/py_feature2d/py_matcher/py_matcher.html
> for
> the full Python code.)
>
>
> Everything up to the point of drawMatchesKnn() works fine, but I have
> issues with the outImg argument when converting to Julia.
>
>
> Documentation for drawMatchesKnn() is pasted below:
> (and can also be found here:
>
> http://docs.opencv.org/3.0-beta/modules/features2d/doc/drawing_function_of_keypoints_and_matches.html#drawmatches
>
>
> Python: cv2.drawMatchesKnn(img1, keypoints1, img2, keypoints2,
> matches1to2[, outImg[, matchColor[, singlePointColor[, matchesMask[,
> flags]]]]]) → outImg
>
> Parameter description:
>
> - img1 – First source image.
> - keypoints1 – Keypoints from the first source image.
> - img2 – Second source image.
> - keypoints2 – Keypoints from the second source image.
> - matches1to2 – Matches from the first image to the second one, which
> means that keypoints1[i] has a corresponding point in
> keypoints2[matches[i]] .
> - outImg – Output image. Its content depends on the flags value
> defining what is drawn in the output image. See possible flags bit values
> below.
> - matchColor – Color of matches (lines and connected keypoints). If
> matchColor==Scalar::all(-1) , the color is generated randomly.
> - singlePointColor – Color of single keypoints (circles), which means
> that keypoints do not have the matches. If
> singlePointColor==Scalar::all(-1) , the color is generated randomly.
> - matchesMask – Mask determining which matches are drawn. If the mask
> is empty, all matches are drawn.
> - flags – Flags setting drawing features. Possible flags bit values
> are defined by DrawMatchesFlags.
>
> As you can see from the sample program, the drawMatchesKnn() line in
> Python would look like this:
> img3 = cv2.drawMatchesKnn(train,kp1,query,kp2,good,None,flags=2) (the key
> argument is argument 6, specified as "None")
>
>
> I'm having problems because I don't really know what an equivalent,
> working example in Julia would be.
>
>
>
> I tried this:
> img3 = cv2.drawMatchesKnn(train,kp1,query,kp2,good)
>
> And got this error: (so arg6 is required)
>
> LoadError: PyError (:PyObject_Call) <type 'exceptions.TypeError'>
> TypeError("Required argument 'outImg' (pos 6) not found",)
>
>
>
> This: (passing the scalar value 0, which worked for the method
> drawKeyPoints() in another program)
> img3 = cv2.drawMatchesKnn(train,kp1,query,kp2,good,0,flags=2)
>
> and got this error:
>
> LoadError: PyError (:PyObject_Call) <type 'exceptions.SystemError'>
> SystemError('NULL result without error in PyObject_Call',)
>
>
>
> and this:
> img3 = cv2.drawMatchesKnn(train,kp1,query,kp2,good,nothing,flags=2)
>
> and got this error:
>
> LoadError: PyError (:PyObject_Call) <type 'exceptions.SystemError'>
> SystemError('NULL result without error in PyObject_Call',)
>
>
> Seems tricky to me because None in Python and nothing in Julia do not
> appear to behave the same way.
>
>
> Anything else I could try? What could the problem be, and how can I fix it?
>
>
> Thanks for reading!
> Any help is much appreciated.
>
