dual_return_outlier_filter#
Purpose#
The purpose is to remove point cloud noise such as fog and rain and publish visibility as a diagnostic topic.
Inner-workings / Algorithms#
This node can remove rain and fog by considering the light reflected from the object in two stages according to the attenuation factor. The dual_return_outlier_filter is named because it removes noise using data that contains two types of return values separated by attenuation factor, as shown in the figure below.
Therefore, in order to use this node, the sensor driver must publish custom data including return_type. please refer to PointXYZIRCAEDT data structure.
Another feature of this node is that it publishes visibility as a diagnostic topic. With this function, for example, in heavy rain, the sensing module can notify that the processing performance has reached its limit, which can lead to ensuring the safety of the vehicle.
In some complicated road scenes where normal objects also reflect the light in two stages, for instance plants, leaves, some plastic net etc, the visibility faces some drop in fine weather condition. To deal with that, optional settings of a region of interest (ROI) are added.
Fixed_xyz_ROImode: Visibility estimation based on the weak points in a fixed cuboid surrounding region of ego-vehicle, defined by x, y, z in base_link perspective.Fixed_azimuth_ROImode: Visibility estimation based on the weak points in a fixed surrounding region of ego-vehicle, defined by azimuth and distance of LiDAR perspective.
When select 2 fixed ROI modes, due to the range of weak points is shrink, the sensitivity of visibility is decrease so that a trade of between weak_first_local_noise_threshold and visibility_threshold is needed.
The figure below describe how the node works.
The below picture shows the ROI options.
Inputs / Outputs#
This implementation inherits autoware::pointcloud_preprocessor::Filter class, please refer README.
Output#
| Name | Type | Description |
|---|---|---|
/dual_return_outlier_filter/frequency_image |
sensor_msgs::msg::Image |
The histogram image that represent visibility |
/dual_return_outlier_filter/visibility |
autoware_internal_debug_msgs::msg::Float32Stamped |
A representation of visibility with a value from 0 to 1 |
/dual_return_outlier_filter/pointcloud_noise |
sensor_msgs::msg::Pointcloud2 |
The pointcloud removed as noise |
Parameters#
Node Parameters#
This implementation inherits autoware::pointcloud_preprocessor::Filter class, please refer README.
Core Parameters#
| Name | Type | Description | Default | Range |
|---|---|---|---|---|
| x_max | float | Maximum of x in meters for Fixed_xyz_ROI mode |
18.0 | N/A |
| x_min | float | Minimum of x in meters for Fixed_xyz_ROI mode |
-12.0 | N/A |
| y_max | float | Maximum of y in meters for Fixed_xyz_ROI mode |
2.0 | N/A |
| y_min | float | Minimum of y in meters for Fixed_xyz_ROI mode |
-2.0 | N/A |
| z_max | float | Maximum of z in meters for Fixed_xyz_ROI mode |
10.0 | N/A |
| z_min | float | Minimum of z in meters for Fixed_xyz_ROI mode |
0.0 | N/A |
| min_azimuth_deg | float | The left limit of azimuth in degrees for Fixed_azimuth_ROI mode |
135.0 | ≥0 ≤360 |
| max_azimuth_deg | float | The right limit of azimuth in degrees for Fixed_azimuth_ROI mode |
225.0 | ≥0 ≤360 |
| max_distance | float | The limit distance in meters for Fixed_azimuth_ROI mode |
12.0 | ≥0.0 |
| vertical_bins | integer | The number of vertical bins for the visibility histogram | 128 | ≥1 |
| max_azimuth_diff | float | The azimuth difference threshold in degrees for ring_outlier_filter | 50.0 | ≥0.0 |
| weak_first_distance_ratio | float | The maximum allowed ratio between consecutive weak point distances | 1.004 | ≥0.0 |
| general_distance_ratio | float | The maximum allowed ratio between consecutive normal point distances | 1.03 | ≥0.0 |
| weak_first_local_noise_threshold | integer | If the number of outliers among weak points is less than the weak_first_local_noise_threshold in the (max_azimuth - min_azimuth) / horizontal_bins interval, all points within the interval will not be filtered out. | 2 | ≥0 |
| roi_mode | string | roi mode | Fixed_xyz_ROI | ['Fixed_xyz_ROI', 'No_ROI', 'Fixed_azimuth_ROI'] |
| visibility_error_threshold | float | When the proportion of white pixels in the binary histogram falls below this parameter the diagnostic status becomes ERR | 0.5 | ≥0.0 ≤1.0 |
| visibility_warn_threshold | float | When the proportion of white pixels in the binary histogram falls below this parameter the diagnostic status becomes WARN | 0.7 | ≥0.0 ≤1.0 |
Assumptions / Known limits#
Not recommended for use as it is under development.
Input data must be PointXYZIRCAEDT type data including return_type.