无法在BackgroundSubtractorMOG2中设置用户参数

Question

OpenCV库版本2.42.我想在BackgroundSubtractorMOG2对象中设置一个参数,例如

BackgroundSubtractorMOG2 bgr;  

// the following doesn't work because 'nmixtures', 'backgroundRatio' 
// and 'fVarMin' are a protected members.
bgr.nmixtures = 3;   
bgr.backgroundRatio = 0.9;
bgr.fVarMin = 5; 

// the following works 
bgr.set('nmixtures', 3); 

// both of the following lines will give a run-time error 
// `Access violation reading location 0x0000000000000008.`
bgr.set("backgroundRatio", 0.9);  
bgr.set("fVarMin", 5);     

backgroundRatio并且fVarMin是控制算法的参数.用户应该能够根据文档更改这些参数.

我该如何设置参数BackgroundSubtractorMOG2？

编辑正如下面的答案中正确提到的,这是OpenCV中的一个错误.该错误已在OpenCV版本2.4.6中修复.

Answer 1

我刚刚查看了OpenCV源代码,发现文件中有趣的初始化/modules/video/src/video_init.cpp.这里是:

CV_INIT_ALGORITHM(BackgroundSubtractorMOG2, "BackgroundSubtractor.MOG2",
    obj.info()->addParam(obj, "history", obj.history);
    obj.info()->addParam(obj, "nmixtures", obj.nmixtures);
    obj.info()->addParam(obj, "varThreshold", obj.varThreshold);
    obj.info()->addParam(obj, "detectShadows", obj.bShadowDetection));

似乎可以使用方法仅设置这四个参数set.

还要看看modules/video/src/bgfg_gaussmix2.cpp有一个BackgroundSubtractorMOG2类的文件.它有以下字段:

float fVarInit;
float fVarMax;
float fVarMin;
//initial standard deviation  for the newly generated components.
//It will will influence the speed of adaptation. A good guess should be made.
//A simple way is to estimate the typical standard deviation from the images.
//I used here 10 as a reasonable value

并且值fVarMin(您想要更改)设置为:

fVarMin = defaultVarMin2

在两个构造函数中.以下是所有这些:

static const float defaultVarInit2 = 15.0f; // initial variance for new components
static const float defaultVarMax2 = 5*defaultVarInit2;
static const float defaultVarMin2 = 4.0f;

有趣的是,这个值没有在任何其他文件中使用,所以现在似乎无法改变它.您可以将此问题直接发布到OpenCV bugtracker.