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| 1 | +# euclidean_cluster |
| 2 | + |
| 3 | +## Purpose |
| 4 | + |
| 5 | +euclidean_cluster is a package for clustering points into smaller parts to classify objects. |
| 6 | + |
| 7 | +This package has two clustering methods: `euclidean_cluster` and `voxel_grid_based_euclidean_cluster`. |
| 8 | + |
| 9 | +## Inner-workings / Algorithms |
| 10 | + |
| 11 | +### euclidean_cluster |
| 12 | + |
| 13 | +`pcl::EuclideanClusterExtraction` is applied to points. See [official document](https://pcl.readthedocs.io/en/latest/cluster_extraction.html) for details. |
| 14 | + |
| 15 | +### voxel_grid_based_euclidean_cluster |
| 16 | + |
| 17 | +1. A centroid in each voxel is calculated by `pcl::VoxelGrid`. |
| 18 | +2. The centroids are clustered by `pcl::EuclideanClusterExtraction`. |
| 19 | +3. The input points are clustered based on the clustered centroids. |
| 20 | + |
| 21 | +## Inputs / Outputs |
| 22 | + |
| 23 | +### Input |
| 24 | + |
| 25 | +| Name | Type | Description | |
| 26 | +| ------- | ------------------------------- | ---------------- | |
| 27 | +| `input` | `sensor_msgs::msg::PointCloud2` | input pointcloud | |
| 28 | + |
| 29 | +### Output |
| 30 | + |
| 31 | +| Name | Type | Description | |
| 32 | +| ---------------- | ----------------------------------------------------------- | -------------------------------------------- | |
| 33 | +| `output` | `autoware_perception_msgs::msg::DetectedObjectsWithFeature` | cluster pointcloud | |
| 34 | +| `debug/clusters` | `sensor_msgs::msg::PointCloud2` | colored cluster pointcloud for visualization | |
| 35 | + |
| 36 | +## Parameters |
| 37 | + |
| 38 | +### Core Parameters |
| 39 | + |
| 40 | +#### euclidean_cluster |
| 41 | + |
| 42 | +| Name | Type | Description | |
| 43 | +| ------------------ | ----- | -------------------------------------------------------------------------------------------- | |
| 44 | +| `use_height` | bool | use point.z for clustering | |
| 45 | +| `min_cluster_size` | int | the minimum number of points that a cluster needs to contain in order to be considered valid | |
| 46 | +| `max_cluster_size` | int | the maximum number of points that a cluster needs to contain in order to be considered valid | |
| 47 | +| `tolerance` | float | the spatial cluster tolerance as a measure in the L2 Euclidean space | |
| 48 | + |
| 49 | +#### voxel_grid_based_euclidean_cluster |
| 50 | + |
| 51 | +| Name | Type | Description | |
| 52 | +| ----------------------------- | ----- | -------------------------------------------------------------------------------------------- | |
| 53 | +| `use_height` | bool | use point.z for clustering | |
| 54 | +| `min_cluster_size` | int | the minimum number of points that a cluster needs to contain in order to be considered valid | |
| 55 | +| `max_cluster_size` | int | the maximum number of points that a cluster needs to contain in order to be considered valid | |
| 56 | +| `tolerance` | float | the spatial cluster tolerance as a measure in the L2 Euclidean space | |
| 57 | +| `voxel_leaf_size` | float | the voxel leaf size of x and y | |
| 58 | +| `min_points_number_per_voxel` | int | the minimum number of points for a voxel | |
| 59 | + |
| 60 | +## Assumptions / Known limits |
| 61 | + |
| 62 | +<!-- Write assumptions and limitations of your implementation. |
| 63 | +
|
| 64 | +Example: |
| 65 | + This algorithm assumes obstacles are not moving, so if they rapidly move after the vehicle started to avoid them, it might collide with them. |
| 66 | + Also, this algorithm doesn't care about blind spots. In general, since too close obstacles aren't visible due to the sensing performance limit, please take enough margin to obstacles. |
| 67 | +--> |
| 68 | + |
| 69 | +## (Optional) Error detection and handling |
| 70 | + |
| 71 | +<!-- Write how to detect errors and how to recover from them. |
| 72 | +
|
| 73 | +Example: |
| 74 | + This package can handle up to 20 obstacles. If more obstacles found, this node will give up and raise diagnostic errors. |
| 75 | +--> |
| 76 | + |
| 77 | +## (Optional) Performance characterization |
| 78 | + |
| 79 | +<!-- Write performance information like complexity. If it wouldn't be the bottleneck, not necessary. |
| 80 | +
|
| 81 | +Example: |
| 82 | + ### Complexity |
| 83 | +
|
| 84 | + This algorithm is O(N). |
| 85 | +
|
| 86 | + ### Processing time |
| 87 | +
|
| 88 | + ... |
| 89 | +--> |
| 90 | + |
| 91 | +## (Optional) References/External links |
| 92 | + |
| 93 | +<!-- Write links you referred to when you implemented. |
| 94 | +
|
| 95 | +Example: |
| 96 | + [1] {link_to_a_thesis} |
| 97 | + [2] {link_to_an_issue} |
| 98 | +--> |
| 99 | + |
| 100 | +## (Optional) Future extensions / Unimplemented parts |
| 101 | + |
| 102 | +The `use_height` option of `voxel_grid_based_euclidean_cluster` isn't implemented yet. |
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