Fixes #341

[oceanusxiv]

This pull request is in regards to #341

After filing the bug report I went an did some digging to figure out why the bug was occurring.
As it turns out, in laser_scan_display:75, the function call:

    projector_->transformLaserScanToPointCloud(
      fixed_frame_.toStdString(),
      *scan,
      *cloud,
      *buffer,
      laser_geometry::channel_option::Intensity);

calls a function in laser_geometry with a prototype as such:

  void transformLaserScanToPointCloud(
    const std::string & target_frame,
    const sensor_msgs::msg::LaserScan & scan_in,
    sensor_msgs::msg::PointCloud2 & cloud_out,
    tf2::BufferCore & tf,
    double range_cutoff = -1.0,
    int channel_options = channel_option::Default)

The relevant parameter here is the range_cutoff, which controls at what range reading the transform should discard the readings. By default this value is implicitly set to -1 as seen, which means the range_cutoff would be inherited from the max_range of the incoming Laserscan, this is usually desired behavior.

However, range_cutoff is not the only default argument, channel_options is one as well, and the bug was caused by ambigious interpretation of the arguments due to the original call above omitting the range_cutoff. Since both arguments can be implicitly converted to one another's type, both are default, and range_cutoff comes first, this results in the interpretation that

range_cutoff = laser_geometry::channel_option::Intensity

cutoff is one meter because laser_geometry::channel_option::Intensity = 0x01

The proposed fix is the simplest possible solution, which is to explicitly set range_cutoff and correct the positioning.

[MarcTestier]

Indeed, the problem is that ROS 1 LaserProjection class has multiple definitions of the transformLaserScanToPointCloud function as seen here :

whereas the ROS 2 LaserProjection class only propose one :
void transformLaserScanToPointCloud( const std::string & target_frame, const sensor_msgs::msg::LaserScan & scan_in, sensor_msgs::msg::PointCloud2 & cloud_out, tf2::BufferCore & tf, double range_cutoff = -1.0, int channel_options = channel_option::Default)

Another solution would be that the ROS 2 LaserProjection class propose multiple definitions of transformLaserScanToPointCloud just like ROS 1. That would avoid other potential conflict like this one.

[mjcarroll]

• Linux
• Linux-aarch64
• macOS
• Windows

[mjcarroll]

Confirmed that the behavior exists and that this fixes it, so LGTM.