OpenCV unhandled exception - c++

Question

I am a hardware (arduino hobbyist) programmer trying to get into OpenCV but struggling with a random error.
I have been following Adam Hacks youtibe guide to OpenCV and up to very recently it has worked great. I had compiled OpenCV as 32bit as the prebuilt was only available in x64 and my intended application (driving a set of servos via a FT232H usb to I2C adapter) was in 32 bit.
I typed in his code for "Using OpenCV and Haar Cascades to Detect Faces in a Video [C++]" and it worked fine (see below). It identified my face (some of the time) and drew a box round it. Yeah I was very happy.
The code:
#include <opencv2/opencv.hpp>
#include <vector>
using namespace std;
/* Include D2XX header*/
#include "ftd2xx.h"
/* Include libMPSSE header */
#include "libMPSSE_i2c.h"
#include "FT232.h"
using namespace cv;
int main()
{
//FT232 ft232;
//ft232.setUpFT232H();
double scale = 1.0;
CascadeClassifier faceCascade;
faceCascade.load("C:\\OpenCV32\\etc\\haarcascade_frontalface_alt.xml");
VideoCapture cap(0);
if (!cap.isOpened())
return -1;
for (;;)
{
Mat frame;
cap >> frame;
Mat grayscale;
cvtColor(frame, grayscale, COLOR_BGR2GRAY);
resize(grayscale, grayscale, Size(grayscale.size().width / scale, grayscale.size().height / scale));
vector <Rect> faces;
faceCascade.detectMultiScale(grayscale, faces, 1.1, 3, 0, Size(30, 30));
for (Rect area : faces) {
Scalar drawColor = Scalar(255, 0, 0);
rectangle(frame, Point(cvRound(area.x * scale), cvRound(area.y * scale)),
Point(cvRound((area.x + area.width-1)*scale), cvRound((area.y + area.height - 1) * scale)), drawColor);
}
imshow("Webcam Frame", frame);
if (waitKey(30) >= 0)
break;
}
return 0;
}
Then with no intentional changes on my part other that swapping about from one haarcascade to another the program stopped working and threw an unhandled error.
Unhandled exception at 0x76979862 in OpenCV_Nerf.exe: Microsoft C++ exception: cv::Exception at memory location 0x00EFF428. occurred
in this part of the system.cpp code
void error( const Exception& exc )
{
#ifdef CV_ERROR_SET_TERMINATE_HANDLER
{
cv::AutoLock lock(getInitializationMutex());
if (!cv_terminate_handler_installed)
{
if (param_setupTerminateHandler)
cv_old_terminate_handler = std::set_terminate(cv_terminate_handler);
cv_terminate_handler_installed = true;
}
cv_terminate_handler_exception = exc;
}
#endif
if (customErrorCallback != 0)
customErrorCallback(exc.code, exc.func.c_str(), exc.err.c_str(),
exc.file.c_str(), exc.line, customErrorCallbackData);
else if (param_dumpErrors)
{
dumpException(exc);
}
if(breakOnError)
{
static volatile int* p = 0;
*p = 0;
}
throw exc;
#ifdef __GNUC__
# if !defined __clang__ && !defined __APPLE__
// this suppresses this warning: "noreturn" function does return [enabled by default]
__builtin_trap();
// or use infinite loop: for (;;) {}
# endif
#endif
}
the error box pointing to the very last line.
The camera still functions and I have narrowed it down to the line
faceCascade.detectMultiScale(grayscale, faces, 1.1, 3, 0, Size(30, 30));
Build output: (I don't remember the warnings about loss of data first few time,, but I can't be sure)
1>------ Rebuild All started: Project: OpenCV_Nerf, Configuration: Debug Win32 ------
1>Source.cpp
1>D:\Vincent\Documents\Programming\Visual Studio Projects\OpenCV_Nerf\Source.cpp(32,93): warning C4244: 'argument': conversion from 'double' to '_Tp', possible loss of data
1> with
1> [
1> _Tp=int
1> ]
1>D:\Vincent\Documents\Programming\Visual Studio Projects\OpenCV_Nerf\Source.cpp(32,60): warning C4244: 'argument': conversion from 'double' to '_Tp', possible loss of data
1> with
1> [
1> _Tp=int
1> ]
1>OpenCV_Nerf.vcxproj -> D:\Vincent\Documents\Programming\Visual Studio Projects\OpenCV_Nerf\Debug\OpenCV_Nerf.exe
1>Done building project "OpenCV_Nerf.vcxproj".
Debug output (last bit as it was over character count)
'OpenCV_Nerf.exe' (Win32): Loaded 'C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_95bdb3a23d6478de\NvCamera\NvCameraWhitelisting32.dll'. Symbol loading disabled by Include/Exclude setting.
'OpenCV_Nerf.exe' (Win32): Unloaded 'C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_95bdb3a23d6478de\NvCamera\NvCameraWhitelisting32.dll'
'OpenCV_Nerf.exe' (Win32): Loaded 'C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_95bdb3a23d6478de\NvCamera\NvCameraWhitelisting32.dll'. Symbol loading disabled by Include/Exclude setting.
'OpenCV_Nerf.exe' (Win32): Unloaded 'C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_95bdb3a23d6478de\NvCamera\NvCameraWhitelisting32.dll'
'OpenCV_Nerf.exe' (Win32): Loaded 'C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_95bdb3a23d6478de\NvCamera\NvCameraWhitelisting32.dll'. Symbol loading disabled by Include/Exclude setting.
'OpenCV_Nerf.exe' (Win32): Unloaded 'C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_95bdb3a23d6478de\NvCamera\NvCameraWhitelisting32.dll'
'OpenCV_Nerf.exe' (Win32): Loaded 'C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_95bdb3a23d6478de\NvCamera\NvCameraWhitelisting32.dll'. Symbol loading disabled by Include/Exclude setting.
'OpenCV_Nerf.exe' (Win32): Unloaded 'C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_95bdb3a23d6478de\NvCamera\NvCameraWhitelisting32.dll'
The thread 0x31a8 has exited with code 0 (0x0).
The thread 0x1f70 has exited with code 0 (0x0).
The thread 0x3668 has exited with code 0 (0x0).
The thread 0x3698 has exited with code 0 (0x0).
The thread 0x3a34 has exited with code 0 (0x0).
The thread 0x374 has exited with code 0 (0x0).
The thread 0x5d8 has exited with code 0 (0x0).
The thread 0x3288 has exited with code 0 (0x0).
The thread 0x35bc has exited with code 0 (0x0).
The thread 0x348c has exited with code 0 (0x0).
The thread 0x3968 has exited with code 0 (0x0).
The thread 0x8c0 has exited with code 0 (0x0).
The thread 0x1068 has exited with code 0 (0x0).
The thread 0x1ef8 has exited with code 0 (0x0).
The thread 0x3a30 has exited with code 0 (0x0).
The thread 0x184c has exited with code 0 (0x0).
The thread 0x37f8 has exited with code 0 (0x0).
The thread 0x18b4 has exited with code 0 (0x0).
The thread 0x3380 has exited with code 0 (0x0).
The thread 0x3bf8 has exited with code 0 (0x0).
'OpenCV_Nerf.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvproc.dll'. Symbol loading disabled by Include/Exclude setting.
Exception thrown at 0x76979862 in OpenCV_Nerf.exe: Microsoft C++ exception: cv::Exception at memory location 0x00FCF7EC.
Unhandled exception at 0x76979862 in OpenCV_Nerf.exe: Microsoft C++ exception: cv::Exception at memory location 0x00FCF7EC.
I am completely stumped and would really appreciate any help or pointers I could get.
Regards