Read and write pcd file without PCL (Point Cloud library)

Question

I'm trying to write a program that reads and writes PCL files without PCD (Point Cloud library), I can read the positions of each point without a problem, but the RGB value is written in uint32_t and I do not know how to read this format and translate it to RGB values.

# .PCD v0.7 - Point Cloud Data file format
VERSION 0.7
FIELDS x y z rgb
SIZE 4 4 4 4
TYPE F F F F
COUNT 1 1 1 1
WIDTH 100
HEIGHT 1
VIEWPOINT 0 0 0 1 0 0 0
POINTS 100
DATA ascii
-0.031568773 -0.99000001 0.99000013 2.3418052e-038
0.031568673 -0.98999995 0.99000013 2.3418052e-038
-0.031568974 -0.54999995 0.77000004 2.3418052e-038
0.031568889 -0.54999995 0.77000004 2.3418052e-038

convert the last value (2.3418052e-038) to RGB value?

Is there a way to do this without Point Cloud library?

Thank you.

Answer 1

Please read the below PLY format data from Wikipedia,

https://en.wikipedia.org/wiki/PLY_(file_format)

Adding a sample snippet to write a PLY file,

std::string fname = "sample.ply";
std::ofstream out(fname);
out << "ply\n";
out << "format ascii 1.0\n";
out << "comment\n";
out << "element vertex " << cloud5->points.size() << "\n";
out << "property float" << sizeof(float) * 8 << " x\n";
out << "property float" << sizeof(float) * 8 << " y\n";
out << "property float" << sizeof(float) * 8 << " z\n";
out << "property uchar red\n";
out << "property uchar green\n";
out << "property uchar blue\n";
out << "property list uchar int vertex_indices\n";
out << "end_header\n";
out.close();

out.open(fname, std::ios_base::app);
for (size_t i = 0; i < cloud5->points.size(); ++i)
{
    out << cloud5->points[i].x << " " << cloud5->points[i].y << " " << cloud5->points[i].z << " " << (int)cloud5->points[i].r 
        << " " << (int)cloud5->points[i].g << " " << (int)cloud5->points[i].b << "\n";
}
out.close();