Question

我正在研究Structure from Motion。我认为，当它从运动中构建时，人们会遇到MultiView Geometry一书。这是一本非常好的书，但我在那本书中发现了令人困惑的数据。在下面的代码中，有一个名为Populate point cloud的函数，它有两个参数pointcloud和pointcloud_RGB。我在pointcloud中有point3d类型的值，但我在该书中找不到关于pointcloud_RGB的任何内容，它突然出现在这个函数中，用于填充VEC3d rgbv。有人可以帮助谁来看看这本书。

void PopulatePCLPointCloud(const vector<cv::Point3d>& pointcloud, 
  const std::vector<cv::Vec3b>& pointcloud_RGB = std::vector<cv::Vec3b>() 
) 

{ 
cout<<"Creating point cloud..."; 
cloud.reset(new pcl::PointCloud<pcl::PointXYZRGB>); 

for (unsigned int i=0; i<pointcloud.size(); i++) { 
// get the RGB color value for the point 
        cv::Vec3b rgbv(255,255,255); 

if (i < pointcloud_RGB.size()) { 
rgbv = pointcloud_RGB[i]; 
} 

        // check for erroneous coordinates (NaN, Inf, etc.) 
                if (pointcloud[i].x != pointcloud[i].x || 
                        pointcloud[i].y != pointcloud[i].y || 
                        pointcloud[i].z != pointcloud[i].z || 
#ifndef WIN32 
                        isnan(pointcloud[i].x) || 
                        isnan(pointcloud[i].y) || 
                        isnan(pointcloud[i].z) || 
#else 
                        _isnan(pointcloud[i].x) || 
                        _isnan(pointcloud[i].y) || 
                        _isnan(pointcloud[i].z) || 
                        false 
                        ) 
                { 
                        continue; 
                } 
pcl::PointXYZRGB pclp; 
pclp.x = pointcloud[i].x; 
pclp.y = pointcloud[i].y; 
pclp.z = pointcloud[i].z; 
// RGB color, needs to be represented as an integer 
uint32_t rgb = ((uint32_t)rgbv[2] << 16 | (uint32_t)rgbv[1] << 8 | 
(uint32_t)rgbv[0]); 
pclp.rgb = *reinterpret_cast<float*>(&rgb); 
cloud->push_back(pclp); 
} 
cloud->width = (uint32_t) cloud->points.size(); // number of points 
cloud->height = 1; // a list of points, one row of data 

//Create visualizer 

pcl::visualization::CloudViewer viewer ("Simple Cloud Viewer"); 
viewer.showCloud (cloud); 

                 cv::waitKey(0); 
                 return; 
}

Answer 1

我相信这是MasteringOpenCV的代码片段 - 第4章。我检查了整个项目，看来这是某种错误pointcloud_RGB定义在

const std::vector<cv::Vec3b>& pointcloud_RGB = std::vector<cv::Vec3b>()

除了此处没有赋值;

rgbv = pointcloud_RGB[i];

这是在

的条件下

if (i < pointcloud_RGB.size())

如果由于pointcloud_RGB为空而且因此不能大于i，程序将永远不会进入此程序。这就是为什么它应该没有任何问题。

实际点云为pcl::PointXYZRGB pclp;，此处用XYZ坐标+ RGB值填充;

pcl::PointXYZRGB pclp; 
pclp.x = pointcloud[i].x; 
pclp.y = pointcloud[i].y; 
pclp.z = pointcloud[i].z; 
// RGB color, needs to be represented as an integer 
uint32_t rgb = ((uint32_t)rgbv[2] << 16 | (uint32_t)rgbv[1] << 8 | 
(uint32_t)rgbv[0]);

当然，总有可能向作者发送电子邮件并要求澄清。

Motion Visualizer的结构

1 个答案: