mirror of
https://github.com/opencv/opencv.git
synced 2024-12-23 07:58:00 +08:00
116 lines
2.9 KiB
ReStructuredText
116 lines
2.9 KiB
ReStructuredText
.. _hull:
|
|
|
|
Convex Hull
|
|
***********
|
|
|
|
Goal
|
|
=====
|
|
|
|
In this tutorial you will learn how to:
|
|
|
|
.. container:: enumeratevisibleitemswithsquare
|
|
|
|
* Use the OpenCV function :convex_hull:`convexHull <>`
|
|
|
|
|
|
Theory
|
|
======
|
|
|
|
Code
|
|
====
|
|
|
|
This tutorial code's is shown lines below. You can also download it from `here <http://code.opencv.org/projects/opencv/repository/revisions/master/raw/samples/cpp/tutorial_code/ShapeDescriptors/hull_demo.cpp>`_
|
|
|
|
.. code-block:: cpp
|
|
|
|
#include "opencv2/highgui/highgui.hpp"
|
|
#include "opencv2/imgproc/imgproc.hpp"
|
|
#include <iostream>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
using namespace cv;
|
|
using namespace std;
|
|
|
|
Mat src; Mat src_gray;
|
|
int thresh = 100;
|
|
int max_thresh = 255;
|
|
RNG rng(12345);
|
|
|
|
/// Function header
|
|
void thresh_callback(int, void* );
|
|
|
|
/** @function main */
|
|
int main( int argc, char** argv )
|
|
{
|
|
/// Load source image and convert it to gray
|
|
src = imread( argv[1], 1 );
|
|
|
|
/// Convert image to gray and blur it
|
|
cvtColor( src, src_gray, CV_BGR2GRAY );
|
|
blur( src_gray, src_gray, Size(3,3) );
|
|
|
|
/// Create Window
|
|
char* source_window = "Source";
|
|
namedWindow( source_window, CV_WINDOW_AUTOSIZE );
|
|
imshow( source_window, src );
|
|
|
|
createTrackbar( " Threshold:", "Source", &thresh, max_thresh, thresh_callback );
|
|
thresh_callback( 0, 0 );
|
|
|
|
waitKey(0);
|
|
return(0);
|
|
}
|
|
|
|
/** @function thresh_callback */
|
|
void thresh_callback(int, void* )
|
|
{
|
|
Mat src_copy = src.clone();
|
|
Mat threshold_output;
|
|
vector<vector<Point> > contours;
|
|
vector<Vec4i> hierarchy;
|
|
|
|
/// Detect edges using Threshold
|
|
threshold( src_gray, threshold_output, thresh, 255, THRESH_BINARY );
|
|
|
|
/// Find contours
|
|
findContours( threshold_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );
|
|
|
|
/// Find the convex hull object for each contour
|
|
vector<vector<Point> >hull( contours.size() );
|
|
for( int i = 0; i < contours.size(); i++ )
|
|
{ convexHull( Mat(contours[i]), hull[i], false ); }
|
|
|
|
/// Draw contours + hull results
|
|
Mat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );
|
|
for( int i = 0; i< contours.size(); i++ )
|
|
{
|
|
Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );
|
|
drawContours( drawing, contours, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
|
|
drawContours( drawing, hull, i, color, 1, 8, vector<Vec4i>(), 0, Point() );
|
|
}
|
|
|
|
/// Show in a window
|
|
namedWindow( "Hull demo", CV_WINDOW_AUTOSIZE );
|
|
imshow( "Hull demo", drawing );
|
|
}
|
|
|
|
|
|
Explanation
|
|
============
|
|
|
|
Result
|
|
======
|
|
|
|
#. Here it is:
|
|
|
|
========== ==========
|
|
|Hull_0| |Hull_1|
|
|
========== ==========
|
|
|
|
.. |Hull_0| image:: images/Hull_Original_Image.jpg
|
|
:align: middle
|
|
|
|
.. |Hull_1| image:: images/Hull_Result.jpg
|
|
:align: middle
|