PointCloud2Modifier::setPointCloud2FieldsByString does not support intensity

[john-maidbot]

Bug report

Required Info:

• Operating System:
  • Ubuntu 22.04
• Installation type:
  • apt
• Version or commit hash:
  • c0c0bc57f958eb54a142446f0c2a475754367eee
• DDS implementation:
  • CycloneDDS
• Client library (if applicable):
  • rclcpp

Steps to reproduce issue

    sensor_msgs::msg::PointCloud2::SharedPtr pcl(new sensor_msgs::msg::PointCloud2);
    sensor_msgs::PointCloud2Modifier modifier(*pcl);
    modifier.setPointCloud2FieldsByString(2, "xyz", "intensity");

Expected behavior

Intensity field is created with correct datatype as expected.

Actual behavior

The code crashes with a runtime error.

[deskew_node-1] terminate called after throwing an instance of 'std::runtime_error'
[deskew_node-1]   what():  Field intensity does not exist

Additional information

The intensity field is claimed to be supported here: https://github.com/ros2/common_interfaces/blob/c0c0bc57f958eb54a142446f0c2a475754367eee/sensor_msgs/msg/PointField.msg#L12

Yet it is not implemented here: https://github.com/ros2/common_interfaces/blob/c0c0bc57f958eb54a142446f0c2a475754367eee/sensor_msgs/include/sensor_msgs/impl/point_cloud2_iterator.hpp#L195

Was there a reason for not including the intensity field?

In the meantime, I think I can work around this as follows:

modifier.setPointCloud2Fields(
    4,  // Number of fields
    "x", 1, sensor_msgs::msg::PointField::FLOAT32,  // x field
    "y", 1, sensor_msgs::msg::PointField::FLOAT32,  // y field
    "z", 1, sensor_msgs::msg::PointField::FLOAT32,  // z field
    "intensity", 1, sensor_msgs::msg::PointField::FLOAT32 // intensity field
);

Thank you for your time.