How do I read pcd.bin with pcl?

[RogerAylagas]

Hi,
I know this might be a noob question, but I am trying to read the point cloud of a pcd.bin file of the Lidar using PCL library in C++ but as the extension is pcd.bin loadPCDFile() does not work. I have alredy tried PCDReader but same error occurs

[pcl::PCDReader::readHeader] No points to read

How can I read the binary pointclouds using pcl in c++?

[holger-motional]

Hi,
that is actually a good question! The .pcd.bin extension is a bit confusing. Essentially we took a .pcd file, removed the headers and saved the data in binary format. You can see how we load it here. So the LIDAR data is simply a bunch of float32 = 4 Bytes and each point is described by 5 floats. The following code in Python would print out the numbers:

import numpy as np

file_path = '/data/nuscenes/samples/LIDAR_TOP/n015-2018-07-18-11-50-34+0800__LIDAR_TOP__1531886224949600.pcd.bin'

with open(file_path, "rb") as f:
    number = f.read(4)
    while number != b"":
        print(np.frombuffer(number, dtype=np.float32))
        number = f.read(4)

Now you just need to implement that in C++.

[RogerAylagas]

Thank you for the quick response, just one more question: what are the fields of the points? x ,y ,z and intensity I supose, but what is the 5th field?
Thank you again!

[holger-motional]

As described at https://github.com/nutonomy/nuscenes-devkit/blob/radar-visualization/python-sdk/nuscenes_utils/data_classes.py#L228 , that's the ring index (an integer between 0 and 31). We do not currently use it.

[RogerAylagas]

Oh okey thank you so much!!

[dada9375]

Hi Holger,
unfortunately I cannot find the page https://github.com/nutonomy/nuscenes-devkit/blob/radar-visualization/python-sdk/nuscenes_utils/data_classes.py#L228
Was it removed?

[holger-motional]

Hi @dada9375,
yes, we changed the folder structure a bit. It is now under: https://github.com/nutonomy/nuscenes-devkit/blob/master/python-sdk/nuscenes/utils/data_classes.py#L249

[dada9375]

Thanks Holger