fix(pointcloud_preprocessor): avoid unnecessary data copy

[VRichardJP]

Description

Avoid unnecessary data copy as explained in #998

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[codecov]

Codecov Report

Merging #999 (6e44229) into main (a0ef0e9) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@           Coverage Diff            @@
##            main    #999      +/-   ##
========================================
- Coverage   9.71%   9.71%   -0.01%     
========================================
  Files        953     953              
  Lines      64012   64013       +1     
  Branches   11181   11181              
========================================
  Hits        6217    6217              
- Misses     52632   52633       +1     
  Partials    5163    5163              

Flag	Coverage Δ		*Carryforward flag
differential	0.00% <0.00%> (?)
total	9.69% <0.00%> (ø)		Carriedforward from a0ef0e9

*This pull request uses carry forward flags. Click here to find out more.

Impacted Files	Coverage Δ
sensing/pointcloud_preprocessor/src/filter.cpp	0.00% <0.00%> (ø)

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[yukkysaito]

LGTM

Just a comment.
They were originally copied from perception_ros for the following reasons
https://github.com/autowarefoundation/autoware.universe/tree/main/sensing/pointcloud_preprocessor

However, I am curious as to why the copying is occurring even in the original.
https://github.com/ros-perception/perception_pcl/blob/ros2/pcl_ros/src/pcl_ros/filters/filter.cpp#L71

[VRichardJP]

By the way, it seems there is the same issue with the 2 conditional transform:

autoware.universe/sensing/pointcloud_preprocessor/src/filter.cpp

Lines 176 to 183 in a0ef0e9

	PointCloud2 cloud_transformed;
	if (!pcl_ros::transformPointCloud(tf_output_frame_, output, cloud_transformed, *tf_buffer_)) {
	RCLCPP_ERROR(
	this->get_logger(), "[computePublish] Error converting output dataset from %s to %s.",
	output.header.frame_id.c_str(), tf_output_frame_.c_str());
	return;
	}
	cloud_tf.reset(new PointCloud2(cloud_transformed));

cloud_tf.reset(new PointCloud2(cloud_transformed)); creates a copy of cloud_transformed while it could be also avoided by using a unique_ptr in the first place, like so:

    auto cloud_transformed = std::make_unique<PointCloud2>();
    if (!pcl_ros::transformPointCloud(tf_output_frame_, *cloud_tf, *cloud_transformed, *tf_buffer_)) {
      RCLCPP_ERROR(
        this->get_logger(), "[computePublish] Error converting output dataset from %s to %s.",
        cloud_tf->header.frame_id.c_str(), tf_output_frame_.c_str());
      return;
    }
    cloud_tf = std::move(cloud_transformed);

[yukkysaito]

I'm checking to work correctly

[yukkysaito]

I confirmed to work correctory with tutorial rosbag.

[yukkysaito]

@VRichardJP LGTM
If you are ok, I'll merge this
cc @miursh @aohsato

[VRichardJP]

Yes, thank you :)

[yukkysaito]

@VRichardJP thank you for your contribution 👍