Need small example for cv.findContours

[mekhontsev]

Hello!
Can anybody show me how to use cv.findContours function in Lua, especially second parameter?

c++ prototype:
cv::findContours( InputOutputArray _image, OutputArrayOfArrays _contours,
OutputArray _hierarchy, int mode, int method, Point offset )

Thanks in advance!

[satoren]

I'm sorry. There is no idea right now.
I'm working on improving bind code generator.

[pantaloon]

Any luck with improving the bind code generator ? i'm also looking into how to call the findContours function from Lua but with no success.

[pantaloon]

And here is my lua implementation of it, it works all the way down to the last function where it doesnt contours is of the right kind.

cv = require("cv")
src = cv.imread(filename, 1 );

src_gray = cv.Mat()
cv.cvtColor(src, src_gray, cv.COLOR_BGR2GRAY)

canny_output = cv.Mat()
cv.Canny(src_gray, canny_output, threshold, threshold*2, 3 );

contours = cv.Mat(100, bit.lshift(4,16), cv.Point(0,0))
cv.findContours(canny_output, contours, cv.RETR_TREE, cv.CHAIN_APPROX_SIMPLE)

---

ERROR from findContours:

OpenCV Error: Assertion failed ((_contours.kind() == _InputArray::STD_VECTOR_VECTOR || _contours.kind() == _InputArray::STD_VECTOR_MAT || _contours.kind() == _InputArray::STD_VECTOR_UMAT)) in cv::findContours, file LuaOpenCV\third_party\opencv\modules\imgproc\src\contours.cpp, line 1892
LuaOpenCV\third_party\opencv\modules\imgproc\src\contours.cpp:1892: error: (-215) (_contours.kind() == _InputArray::STD_VECTOR_VECTOR || _contours.kind() == _InputArray::STD_VECTOR_MAT || _contours.kind() ==
_InputArray::STD_VECTOR_UMAT) in function cv::findContours

So basically i can't figure out the syntax to create the InputOutputArray of cv.Points that is expected for the contour to work.

[KellyGodLv]

C++:
using con = std::vector<std::vectorcv::Point>;
class Contour {
public:
Contour() {};
virtual ~Contour() {};
con _con;
};

function("FindContour", [](Mat src, Contour& contours) {
findContours(src, contours._con, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE);
});
function("DrawContour", [](Mat src, Contour& contours,Scalar color) {
drawContours(src, contours._con, -1, color);
});

from lua :
local src=cv.imread(file_name,cv.IMREAD_ANYCOLOR)
local dst_img=src:clone()
cv.cvtColor(src,src,cv.COLOR_BGR2GRAY)
local con=cv.Contour()
cv.FindContour(src,con)
cv.DrawContour(dst_img,con,cv.Scalar(0,0,255))
.......do something...