How can I get rgb value from point cloud - c++

Question

I have a point-cloud. I want to get its RGB value. How can I do that?
To make my question clearer, please see the codes.
// Load the first input file into a PointCloud<T> with an appropriate type :
pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud1 (new pcl::PointCloud<pcl::PointXYZRGB>);
if (pcl::io::loadPCDFile<pcl::PointXYZRGB> ("../data/station1.pcd", *cloud1) == -1)
{
std::cout << "Error reading PCD file !!!" << std::endl;
exit(-1);
}
I want to get each value alone
std::cout << " x = " << cloud1->points[11].x << std::endl;
std::cout << " y = " << cloud1->points[11].y << std::endl;
std::cout << " z = " << cloud1->points[11].z << std::endl;
std::cout << " r = " << cloud1->points[11].r << std::endl;
std::cout << " g = " << cloud1->points[11].g << std::endl;
std::cout << " b = " << cloud1->points[11].b << std::endl;
But as a result I get something like that :
x = 2.33672
y = 3.8102
z = 8.86153
r = �
g = w
b = �

Answer 1

From the point cloud docs:
A point structure representing Euclidean xyz coordinates, and the RGB color.
Due to historical reasons (PCL was first developed as a ROS package), the RGB information is packed into an integer and casted to a float. This is something we wish to remove in the near future, but in the meantime, the following code snippet should help you pack and unpack RGB colors in your PointXYZRGB structure:
// pack r/g/b into rgb
uint8_t r = 255, g = 0, b = 0; // Example: Red color
uint32_t rgb = ((uint32_t)r << 16 | (uint32_t)g << 8 | (uint32_t)b);
p.rgb = *reinterpret_cast<float*>(&rgb);
To unpack the data into separate values, use:
PointXYZRGB p;
// unpack rgb into r/g/b
uint32_t rgb = *reinterpret_cast<int*>(&p.rgb);
uint8_t r = (rgb >> 16) & 0x0000ff;
uint8_t g = (rgb >> 8) & 0x0000ff;
uint8_t b = (rgb) & 0x0000ff;
Alternatively, from 1.1.0 onwards, you can use p.r, p.g, and p.b directly.
Definition at line 559 of file point_types.hpp.