OpenCV Error: Assertion failed (ni > 0 && ni == ni1) - opencv

Question

I have the following problem: Everything works fine, but when i reach the calibrateCamera Part i get the following error:
OpenCV Error: Assertion failed (ni > 0 && ni == ni1) in unknown function, file .
.....\src\opencv\modules\calib3d\src\calibration.cpp, line 3197
I am new here, and maybe my code isn't as clear as it could be, but please be friendly.
Thank you very much in advance.
My code is: (i deleted the include and pragma parts, because it got really big letters here)
int _tmain()
{
printf("Everything loaded. Press Enter to continue.\n\a");
getch();
system("cls"); //bildschirm clearen
int numBoards = 0;
int numCornersHor;
int numCornersVer;
char stCurPath[200];
int numFiles = 0;
char stRemFileNum[200];
int curNum;
vector<string> file_names;
string s;
bool pathok = false;
#pragma region ask user for path to load images and list them
// ask user for path to load images and list them
while(pathok == false)
{
fflush(stdin);
printf("Enter path to the folder where the pictures are:\n");
scanf("%199[^\n]s", stCurPath); //achtung wegen bufferoverflow - nicht mehr als 199 zeichen + EOF (0) einlesen.
//[^\n] wegen Leerzeichen. scanf liest bis Enter.
system("cls");
DIR *dir;
struct dirent *ent;
dir = opendir (stCurPath);
if (dir != NULL) {
/* print all the files and directories within directory */
printf("Your chosen path:\n%s\n\nFiletree of this path:\n", stCurPath);
while ((ent = readdir (dir)) != NULL)
{
numFiles++; //Anzahl der Files
printf ("%d)\t%s\n",numFiles, ent->d_name);
s = ent->d_name;
file_names.push_back(s);
}
closedir (dir);
fflush( stdout );
printf ("\nNumber of found files: %d\n", numFiles);
pathok = true;
}
else
{
/* could not open directory */
printf ("Could not open directory. Make sure path is ok!\n\n");
pathok = false;
/*perror ("");
return EXIT_FAILURE*/;
}
}//while(pathok == false)
/*****************************end ask user for path to load images and list them****************************************/
#pragma endregion
#pragma region ask user to exclude some files
/*****************************************ask user to exclude some files*************************/
printf ("\nEnter the number of the files you dont want to load (number only!).\nSeperate single files with comma.\nEnter 0 if you don't want to exclude files.\nEnter x to exclude all non bmp files.\n\nNumbers:\n");
scanf("%199s", stRemFileNum); //achtung wegen bufferoverflow - nicht mehr als 199 zeichen + EOF (0) einlesen
vector<string>::iterator it;
if(strcmp(stRemFileNum,"x") == 0)
{
curNum=1;
numFiles = 0;
string extstr;
const char * extc;
file_names.erase(remove_if(file_names.begin(),
file_names.end(),
isBmpExtension), file_names.end());
system("cls"); //bildschirm clearen
printf("New Filetree of this path:\n\n");
it = file_names.begin();
for(it; it != file_names.end(); ++it)
{
numFiles++;
printf ("%d)\t%s\n",numFiles, (*it).c_str());
}
printf ("\nNumber of found files: %d\n", numFiles);
}//if(strcmp(stRemFileNum,"x") == 0)
//end user entered x
//start user entered 0
if(strcmp(stRemFileNum,"0") != 0 && strcmp(stRemFileNum,"x") != 0)
{
//fehler
numFiles = 0;
vector<string> numbersVector;
string strNumbers = stRemFileNum;
Tokenize(strNumbers, numbersVector, ",");
sort(numbersVector.begin(), numbersVector.end(), strCompDesc);
for(it = numbersVector.begin(); it != numbersVector.end(); ++it)
{
curNum = atoi((*it).c_str());
file_names.erase(file_names.begin() + (curNum - 1));
}
system("cls"); //bildschirm clearen
printf("New Filetree of this path:\n\n");
//fehler ende
for(vector<string>::iterator it = file_names.begin(); it != file_names.end(); ++it)
{
numFiles++;
printf ("%d)\t%s\n",numFiles, (*it).c_str());
}
printf ("\nNumber of found files: %d\n", numFiles);
}
//user entered 0
else if(strcmp(stRemFileNum,"0") == 0)
{
printf ("\nNo files excluded.\n");
}
/*****************end ask user to exclude some files *******************************************/
#pragma endregion
fflush(stdin);
printf("\nEnter number of corners along width: ");
scanf("%d", &numCornersHor);
fflush(stdin);
printf("Enter number of corners along height: ");
scanf("%d", &numCornersVer);
int numSquares = numCornersHor * numCornersVer;
Size board_sz = Size(numCornersHor, numCornersVer);
vector<vector<Point3f>> object_points;
vector<vector<Point2f>> image_points;
vector<Point2f> corners;
vector<Point3f> obj;
int pictures_done=0;
Mat image;
Mat gray_image;
//Bilder zum persönlichen auswerten anzeigen +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//
for(vector<string>::iterator it = file_names.begin(); it != file_names.end(); ++it)
{
printf("\nLoading Picture..\n");
image = imread(string(stCurPath) + "\\" + (*it).c_str()); //als farbe lesen; doppelter backslash o. normaler
//resize(image, image, Size(0,0), 0.5, 0.5, INTER_AREA);
cvtColor(image,gray_image,CV_RGB2GRAY);
for(int j=0;j<numSquares;j++)
{
obj.push_back(Point3f(j/numCornersHor, j%numCornersHor, 0.0f));
}//for(int j=0;j<numSquares;j++)
bool found = findChessboardCorners(image, board_sz, corners, CV_CALIB_CB_ADAPTIVE_THRESH | CV_CALIB_CB_FILTER_QUADS);
if(found)
{
cornerSubPix(gray_image, corners, Size(11, 11), Size(-1, -1), TermCriteria(CV_TERMCRIT_EPS | CV_TERMCRIT_ITER, 30, 0.1));
drawChessboardCorners(gray_image, board_sz, corners, found);
}
cvNamedWindow("win1", 1);
imshow("win1", gray_image);
waitKey(30);
cvMoveWindow("win1",0,0);
waitKey(30);
printf("\nPicture loaded.\nPress a to load original, s to store snap and show next picture,");
printf("\nd to drop snap and show next picture, and f to close the programm\n");
char key;
bool bOriginalDisplayed = false;
while(1)
{
if (cin.rdbuf()->in_avail())
{
key = _getch();
}
if('a' == key && found!=0)
{
if (!bOriginalDisplayed)
{
printf("\nLoading original..\n");
cvNamedWindow("win2", 1);
cvMoveWindow("win2",0,0);
imshow("win2", image); //oder imshow cvMoveWindow("Smile", 100, 100);
bOriginalDisplayed = true;
waitKey(50);
printf("\nOriginal loaded.\nPess a again to close original before you continue.\n");
}
else
{
cvDestroyWindow("win2");
printf("\nOriginal closed.\n");
bOriginalDisplayed = false;
}
}
if('s'==key)
{
image_points.push_back(corners);
object_points.push_back(obj);
printf("\nSnap stored!\n");
pictures_done++;
found = false;
break;
}
if('d' == key)
{
pictures_done++;
break;
found = false;
}
if('f' == key)
{
return 0;
}
Sleep(50);
} //while (1)
} //for(vector<string>::iterator it = file_names.begin(); it != file_names.end(); ++it)
cvDestroyWindow("win1");
waitKey(50);
Mat intrinsic = Mat(3, 3, CV_32FC1);
Mat distCoeffs;
vector<Mat> rvecs;
vector<Mat> tvecs;
intrinsic.ptr<float>(0)[0] = 1;
intrinsic.ptr<float>(1)[1] = 1;
calibrateCamera(object_points, image_points, image.size(), intrinsic, distCoeffs, rvecs, tvecs);
Mat imageUndistorted;
for(vector<string>::iterator it = file_names.begin(); it != file_names.end(); ++it)
{
printf("\nLoading undistorted Picture..\n");
image = imread(string(stCurPath) + "\\" + (*it).c_str()); //als farbe lesen; doppelter backslash o. normaler
//resize(image, image, Size(0,0), 0.5, 0.5, INTER_AREA);
cvtColor(image,gray_image,CV_RGB2GRAY);
cvNamedWindow("win1", 1);
cvNamedWindow("win2", 1);
cvMoveWindow("win1",0,0);
cvMoveWindow("win2",0,0);
undistort(image, imageUndistorted, intrinsic, distCoeffs);
imshow("win1", image);
waitKey(0);
imshow("win2", imageUndistorted);
waitKey(30);
printf("\nPicture loaded. Press s for the next picture or f to exit.");
char key;
bool bOriginalDisplayed = false;
while(1)
{
if (cin.rdbuf()->in_avail())
{
key = _getch();
}
if('s'==key)
{
break;
}
if('f' == key)
{
return 0;
}
Sleep(50);
} //while (1)
} //for(vector<string>::iterator it = file_names.begin(); it != file_names.end(); ++it)
return 0;
}

Answer 1

If found the problem. And me being a good person i came here to post the answer for people having the same issue in the future.
Solution: Add a obj.clear() into the for function so obj always stays same size when you push back. Like this:
//Bilder zum persönlichen auswerten anzeigen +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//
for(vector<string>::iterator it = file_names.begin(); it != file_names.end(); ++it)
{
printf("\nLoading Picture..\n");
image = imread(string(stCurPath) + "\\" + (*it).c_str()); //als farbe lesen; doppelter backslash o. normaler
//resize(image, image, Size(0,0), 0.5, 0.5, INTER_AREA);
cvtColor(image,gray_image,CV_RGB2GRAY);
obj.clear();
for(int j=0;j<numSquares;j++)
{
obj.push_back(Point3f(j/numCornersHor, j%numCornersHor, 0.0f));
}//for(int j=0;j<numSquares;j++)
bool found = findChessboardCorners(image, board_sz, corners, CV_CALIB_CB_ADAPTIVE_THRESH | CV_CALIB_CB_FILTER_QUADS);
if(found)
Have fun programming. Greets, Escore.