Painterly Rendering, Clipping line, I'm have an error - c++

Question

I'm making a painterly rendering.
And now I'm doing that clipping line things.
But I got this error:
<<unsigned><pt.x*DataType<_Tp>::channels> <<unsigned<size.p[1]*channels<>>>
And
template<typename _Tp> inline const _Tp& Mat::at(int i0, int i1) const
{
CV_DbgAssert( dims <= 2 && data && (unsigned)i0 < (unsigned)size.p[0] &&
(unsigned)(i1*DataType<_Tp>::channels) < (unsigned)(size.p[1]*channels()) &&
CV_ELEM_SIZE1(DataType<_Tp>::depth) == elemSize1());
return ((const _Tp*)(data + step.p[0]*i0))[i1];
}
Maybe this is the error that on 'Lineclipping()'
Please, tell me another good idea that clipped line.
this is my code. And I'm just a student so my codding skill is very beginner.
#include <iostream>
#include <opencv2/opencv.hpp>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <sstream>
#include <cmath>
#include <stdio.h>
#include <cstdlib>
#include <time.h>
#include <random>
using namespace cv;
using namespace std;
random_device rd;
mt19937_64 rng(rd());
double PI = 3.141592;
int perturbLength = (rand() % 6) + 1;
int perturbRadius = ((rand() % 5) + 0) / 10;
int perturbAngle = (rand() % 15) + (-15);
int Maxlength = 10 - perturbLength;
int radius = 2 - perturbRadius;
int angle = 45 - perturbAngle;
double theta = angle*(PI / 180);
void Lineclipping(int x, int y, double theta, int len, Point2d& pt1, Point2d& pt2, Mat& EdgeMap)
{
double length = ceil(len);
enter code here
float detectPT = len / length;
for (int i = detectPT; i <= len;)
{
Point2d Mpt1(x + length*cos(theta), y + length*sin(theta));
if (EdgeMap.at<uchar>(Mpt1.y, Mpt1.x) > 0)
{
pt1.x = Mpt1.x;
pt1.y = Mpt1.y;
}
else if (i == length)
{
pt1.x = Mpt1.x;
pt1.y = Mpt1.y;
}
i = i + detectPT;
}
for (int i = detectPT; i <= len;)
{
Point2d Mpt2(x - length*cos(theta), y - length*sin(theta));
if (EdgeMap.at<uchar>(Mpt2.y, Mpt2.x) > 0)
{
pt2.x = Mpt2.x;
pt2.y = Mpt2.y;
}
else if (i == length)
{
pt2.x = Mpt2.x;
pt2.y = Mpt2.y;
}
i = i + detectPT;
}
}
Mat EdgeDetect(Mat& referenceimg, Mat& Edge)
{
Mat image = referenceimg.clone();
//Make Edge Map
Mat IntensityImg(image.size(), CV_8U, 255);
Mat sobelx, sobely;
for (int i = 0; i < image.rows; i++)
{
for (int j = 0; j < image.cols; j++)
{
Vec3b intensity = image.at<Vec3b>(j, i);
uchar blue = intensity.val[0];
uchar green = intensity.val[1];
uchar red = intensity.val[2];
IntensityImg.at<uchar>(j, i) = (30 * red + 59 * green + 11 * blue) / 100;
}
}
GaussianBlur(IntensityImg, IntensityImg, Size(5, 5), 0.1, 0.1);
Sobel(IntensityImg, sobelx, CV_32F, 1, 0);
Sobel(IntensityImg, sobely, CV_32F, 0, 1);
Mat magnitudeXY = abs(sobelx), abs(sobely);
magnitudeXY.convertTo(Edge, CV_8U);
Mat mask(3, 3, CV_8UC1, 1);
morphologyEx(Edge, Edge, MORPH_ERODE, mask);
for (int i = 0; i < image.rows; i++)
{
for (int j = 0; j < image.cols; j++)
{
Edge.at<uchar>(j, i) = (Edge.at<uchar>(j, i) > 20 ? 255 : 0);
}
}
imshow("intensity", Edge);
return Edge;
}
void paint(Mat &image, int snum)
{
Mat Edge;
EdgeDetect(image, Edge);
for (int n = 0; n < snum; n++)
{
int x = rand() % image.cols;
int y = rand() % image.rows;
if (image.channels() == 1)
{
image.at<uchar>(x, y) = 255;
}
else if (image.channels() == 3)
{
int length = Maxlength / 2;
Point2d pt1(x + length*cos(theta), y + length*sin(theta));
Point2d pt2(x - length*cos(theta), y - length*sin(theta));
Lineclipping(x, y, theta, length, fpt1, fpt2, Edge);
//draw line
Scalar color(image.at<Vec3b>(y, x)[0], image.at<Vec3b>(y, x)[1], image.at<Vec3b>(y, x)[2]);
line(image, pt1, pt2, color, radius);
}
}
}
int main()
{
Mat Img = imread("fruit.jpg", IMREAD_COLOR);
CV_Assert(Img.data);
Mat resultImage = Img.clone();
Mat sobel = Img.clone();
int num = Img.rows*Img.cols;
paint(resultImage, num);
imshow("result", resultImage);
waitKey();
return 0;
}
And This is the error parts.
for (int i = detectPT; i <= len;)
{
Point2d Mpt1(x + length*cos(theta), y + length*sin(theta));
if (EdgeMap.at<uchar>(Mpt1.y, Mpt1.x) > 0)
{
pt1.x = Mpt1.x;
pt1.y = Mpt1.y;
}
else if (i == length)
{
pt1.x = Mpt1.x;
pt1.y = Mpt1.y;
}
i = i + detectPT;
}
for (int i = detectPT; i <= len;)
{
Point2d Mpt2(x - length*cos(theta), y - length*sin(theta));
if (EdgeMap.at<uchar>(Mpt2.y, Mpt2.x) > 0)
{
pt2.x = Mpt2.x;
pt2.y = Mpt2.y;
}
else if (i == length)
{
pt2.x = Mpt2.x;
pt2.y = Mpt2.y;
}
i = i + detectPT;
}
Thank you!

Answer 1

Since I can't compile this and run it, I am going to run through a possible execution and show you where you can hit this out of range error.
int perturbLength = (rand() % 6) + 1; // Range is 1 to 6, let's assume 4
int perturbAngle = (rand() % 15) + (-15); // Range is -15 to -1 let's assume -14
int Maxlength = 10 - perturbLength; // 6
int angle = 45 - perturbAngle; // 44
double theta = angle*(PI / 180); // .7679
Now we get into this code inside the paint method:
int x = rand() % image.cols; // Let's assume image.cols - 2
int y = rand() % image.rows; // Let's assume image.rows - 1
Inside of paint we will reach this code:
int length = Maxlength / 2; // Maxlength is 6 so this is 3
Lineclipping(x, y, theta, length, fpt1, fpt2, Edge);
Which leads to the Lineclipping method and here we get a problem:
Point2d Mpt1(x + length*cos(theta), y + length*sin(theta));
if (EdgeMap.at<uchar>(Mpt1.y, Mpt1.x) > 0)
This is the problem. Remember, x is image.cols - 2. Now we perform the operations x + length * cos(theta), which is (image.cols-2) + 3 * cos(.7679). 3 * cos(.7679) is 2.999 which whether you floor it or round it is going to cause a problem when you add it to image.cols - 2. If it is floored and you get 2 we have image.cols which causes out of range, if it is rounded then we have image.cols + 1, so in either case we go beyond the bounds of the array.