// Uses 4 calibration factors
public float arwCalibChessboardCornersSimple(int numImages, string file_name, out float[] projectErrorResults)
{
projectErrorResults = new float[numImages];
GCHandle handle = GCHandle.Alloc(projectErrorResults, GCHandleType.Pinned);
IntPtr address = handle.AddrOfPinnedObject();
float averageProjectionError = ARNativePlugin.arwCalibChessboardCornersSimple(file_name, address);
handle.Free();
return(averageProjectionError);
}