如何使用 PCL 进行颜色过滤

Question

我正在学习使用pcl.I想过滤掉颜色为红色(rgb 255,0,0)的点云，但不是work.what我应该怎么做？我使用的 PCL 版本是 1.12.1.

#include <pcl/point_types.h>
#include <pcl/filters/conditional_removal.h>
int main()
{
    pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZRGB>);
    pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud_filtered(new 
    pcl::PointCloud<pcl::PointXYZRGB>);

    cloud->width = 5;
    cloud->height = 1;
    cloud->points.resize((cloud->width) * (cloud->height));
    //creat point cloud
    for (size_t i = 0; i < cloud->points.size(); ++i)
    {
       cloud->points[i].x = 1024 * rand() / (RAND_MAX + 1.0f) / 1000;
       cloud->points[i].y = 1024 * rand() / (RAND_MAX + 1.0f) / 1000;
       cloud->points[i].z = 1024 * rand() / (RAND_MAX + 1.0f) / 1000;
       cloud->points[i].r = 110;
       cloud->points[i].g = 110;
       cloud->points[i].b = 110;
    }
   //set rbg 255,0,0
    cloud->points[2].r = 255;cloud->points[2].g = 0;cloud->points[2].b = 0;
    
    pcl::ConditionAnd<pcl::PointXYZRGB>::Ptr range_cond(new pcl::ConditionAnd<pcl::PointXYZRGB>());
    range_cond->addComparison(pcl::FieldComparison<pcl::PointXYZRGB>::ConstPtr(new pcl::FieldComparison<pcl::PointXYZRGB>("r", pcl::ComparisonOps::EQ, 255)));
    range_cond->addComparison(pcl::FieldComparison<pcl::PointXYZRGB>::ConstPtr(new pcl::FieldComparison<pcl::PointXYZRGB>("g", pcl::ComparisonOps::EQ, 0)));
    range_cond->addComparison(pcl::FieldComparison<pcl::PointXYZRGB>::ConstPtr(new pcl::FieldComparison<pcl::PointXYZRGB>("b", pcl::ComparisonOps::EQ, 0)));
   
   pcl::ConditionalRemoval<pcl::PointXYZRGB> condrem;
   condrem.setCondition(range_cond);
   condrem.setInputCloud(cloud);
   condrem.setKeepOrganized(true);
   condrem.filter(*cloud_filtered);
   
   std::cerr << "Cloud before filtering: " << std::endl;
   for (size_t i = 0; i < cloud->points.size(); ++i)
       std::cerr << "    " << cloud->points[i].x << " "
       << cloud->points[i].y << " "
       << cloud->points[i].z << " "
       << (int)cloud->points[i].r << " "
       << (int)cloud->points[i].g << " "
       << (int)cloud->points[i].b << std::endl;

   std::cerr << "Cloud after filtering: " << std::endl;
   for (size_t i = 0; i < cloud_filtered->points.size(); ++i)
      std::cerr << "    " << cloud_filtered->points[i].x << " "
      << cloud_filtered->points[i].y << " "
      << cloud_filtered->points[i].z << " "
      << (int)cloud_filtered->points[i].r << " "
      << (int)cloud_filtered->points[i].g << " "
      << (int)cloud_filtered->points[i].b << std::endl;
   return (0);

}

过滤后的云是None。结果： enter image description here

Answer 1

警告消息提示您：“未找到字段！” （三次）。 PointXYZRGB 没有 r、g 和 b 字段。您可以使用 getFields() 找出点类型具有哪些字段。 PointXYZRGB 有一个可用于过滤的组合字段 rgb。但是，您可能想考虑使用 PointXYZRGBA 代替（使用字段 rgba），因为其他点类型使用 float 进行存储（历史原因），我不确定它的效果如何带过滤。

Answer 2

我修改后的代码在这里：

//creat point cloud
for (size_t i = 0; i < cloud->points.size(); ++i)
{
   cloud->points[i].x = 1024 * rand() / (RAND_MAX + 1.0f) / 1000;
   cloud->points[i].y = 1024 * rand() / (RAND_MAX + 1.0f) / 1000;
   cloud->points[i].z = 1024 * rand() / (RAND_MAX + 1.0f) / 1000;
   cstd::uint32_t rgb = ((std::uint32_t)110 << 16 | (std::uint32_t)110 << 8 | (std::uint32_t)110);
   cloud->points[i].rgb = *reinterpret_cast<float*>(&rgb);
}
//set red rbg 255,0,0
std::uint32_t red_rgb = ((std::uint32_t)255 << 16 | (std::uint32_t)0 << 8 | (std::uint32_t)0);
cloud->points[2].rgb = *reinterpret_cast<float*>(&red_rgb);
std::cerr << " FieldsList:" << pcl::getFieldsList(*cloud) <<std::endl;

pcl::ConditionAnd<pcl::PointXYZRGB>::Ptr range_cond(new pcl::ConditionAnd<pcl::PointXYZRGB>());
std::uint32_t rgb_filter = ((std::uint32_t)255 << 16 | (std::uint32_t)0 << 8 | (std::uint32_t)0);

//Add a comparison operator less than (255,0,0) on the rgb field
range_cond->addComparison(pcl::FieldComparison<pcl::PointXYZRGB>::ConstPtr(new pcl::FieldComparison<pcl::PointXYZRGB>("rgb", pcl::ComparisonOps::LT, *reinterpret_cast<float*>(&rgb_filter))));

最终结果： enter image description here

如何使用 PCL 进行颜色过滤

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