Calling cv::cuda::HOG from python

Question

I need to access the cuda modules of opencv in C++ from python. I tried wrapping the c++ functions using Boost however I get the following error.

ImportError: ../build/lib.linux-x86_64-2.7/pyBoostHOG.so: undefined symbol: _ZN2cv4cuda6Stream4NullEv.

Is there any way by which I can access the opencv cuda modules from python? Thanks in advance..

Answer 1

I had the same error.

I figured out that I must include opencv2/core/cuda.hpp file (symbol _ZN2cv4cuda6Stream4NullEv reffers to: cv::cuda::Stream::Null()

But this doesn't solve the problem, because when I tried to make wrap thought swig and include these file, new error:

.../include/opencv2/core/cuda.hpp:317: Error: Syntax error in input(1).

is displayed. Compiling another program using cv::cuda::Stream::Null() cause not error.

Answer 2

I was facing the same error. And this is how I was compiling the .so file:

g++ `pkg-config opencv4 --cflags --libs` -fPIC -c flow.cpp
g++ -Wall -O3 -shared -o flow.so flow.o `pkg-config opencv4 --cflags --libs`

The error was resolved when I changed my make file to the following:

g++ `pkg-config opencv4 --cflags --libs` -fPIC -c flow.cpp
g++ -Wall -O3 -shared flow.o -o flow.so `pkg-config opencv4 --cflags --libs`