Add drone LiDAR example

examples/manifest.toml

@@ -155,6 +155,7 @@ examples = [
   "custom_data_loader",
   "custom_space_view",
   "custom_store_subscriber",
+  "drone_lidar",
   "extend_viewer_ui",
   "external_data_loader",
   "incremental_logging",

examples/python/drone_lidar/.gitignore

@@ -0,0 +1 @@
+/dataset

examples/python/drone_lidar/README.md

@@ -0,0 +1,40 @@
+<!--[metadata]
+title = "Drone LiDAR"
+tags = ["3D", "drone", "Lidar"]
+description = "Display drone-based LiDAR data"
+-->
+
+<picture>
+  <img src="https://static.rerun.io/drone_lidar/95c49d78abc01513d344c06e2d9a0c8b84376a0d/full.png" alt="">
+  <source media="(max-width: 480px)" srcset="https://static.rerun.io/drone_lidar/95c49d78abc01513d344c06e2d9a0c8b84376a0d/480w.png">
+  <source media="(max-width: 768px)" srcset="https://static.rerun.io/drone_lidar/95c49d78abc01513d344c06e2d9a0c8b84376a0d/768w.png">
+  <source media="(max-width: 1024px)" srcset="https://static.rerun.io/drone_lidar/95c49d78abc01513d344c06e2d9a0c8b84376a0d/1024w.png">
+  <source media="(max-width: 1200px)" srcset="https://static.rerun.io/drone_lidar/95c49d78abc01513d344c06e2d9a0c8b84376a0d/1200w.png">
+</picture>
+
+
+## Background
+
+This example displays drone-based indoor LiDAR data loaded from a [`.las`](https://en.wikipedia.org/wiki/LAS_file_format) file. This dataset contains 18.7M points, acquired at 4013 distinct time points (~4650 points per time point). The point data is loaded using the [laspy](https://laspy.readthedocs.io/en/latest/) Python package, and then sent in one go to the viewer thanks to the [`rr.send_columns()`](https://ref.rerun.io/docs/python/0.18.2/common/columnar_api/#rerun.send_columns) API and its `.partition()` helper. Together, these APIs enable associating subgroups of points with each of their corresponding, non-repeating timestamps.
+
+
+[Flyability](https://www.flyability.com) kindly provided the data for this example.
+
+
+## Running
+
+Install the example package:
+```bash
+pip install -e examples/python/drone_lidar
+```
+
+To experiment with the provided example, simply execute the main Python script:
+```bash
+python -m drone_lidar
+```
+
+If you wish to customize it, explore additional features, or save it, use the CLI with the `--help` option for guidance:
+
+```bash
+python -m drone_lidar --help
+```

examples/python/drone_lidar/drone_lidar.py

@@ -0,0 +1,179 @@
+from __future__ import annotations
+
+import io
+import typing
+import zipfile
+from argparse import ArgumentParser
+from pathlib import Path
+
+import laspy
+import numpy as np
+import numpy.typing as npt
+import requests
+import rerun as rr
+import rerun.blueprint as rrb
+from tqdm import tqdm
+
+DATASET_DIR = Path(__file__).parent / "dataset"
+if not DATASET_DIR.exists():
+    DATASET_DIR.mkdir()
+
+LIDAR_DATA_FILE = DATASET_DIR / "livemap.las"
+TRAJECTORY_DATA_FILE = DATASET_DIR / "livetraj.csv"
+
+LIDAR_DATA_URL = "https://storage.googleapis.com/rerun-example-datasets/flyability/basement/livemap.las.zip"
+TRAJECTORY_DATA_URL = "https://storage.googleapis.com/rerun-example-datasets/flyability/basement/livetraj.csv"
+
+
+def download_with_progress(url: str, what: str) -> io.BytesIO:
+    """Download a file with a tqdm progress bar."""
+    chunk_size = 1024 * 1024
+    resp = requests.get(url, stream=True)
+    total_size = int(resp.headers.get("content-length", 0))
+    with tqdm(
+        desc=f"Downloading {what}",
+        total=total_size,
+        unit="iB",
+        unit_scale=True,
+        unit_divisor=1024,
+    ) as progress:
+        download_file = io.BytesIO()
+        for data in resp.iter_content(chunk_size):
+            download_file.write(data)
+            progress.update(len(data))
+
+    download_file.seek(0)
+    return download_file
+
+
+def unzip_file_from_archive_with_progress(zip_data: typing.BinaryIO, file_name: str, dest_dir: Path) -> None:
+    """Unzip the file named `file_name` from the zip archive contained in `zip_data` to `dest_dir`."""
+    with zipfile.ZipFile(zip_data, "r") as zip_ref:
+        file_info = zip_ref.getinfo(file_name)
+        total_size = file_info.file_size
+
+        with tqdm(
+            total=total_size, desc=f"Extracting file {file_name}", unit="iB", unit_scale=True, unit_divisor=1024
+        ) as progress:
+            with zip_ref.open(file_name) as source, open(dest_dir / file_name, "wb") as target:
+                for chunk in iter(lambda: source.read(1024 * 1024), b""):
+                    target.write(chunk)
+                    progress.update(len(chunk))
+
+
+def download_dataset() -> None:
+    if not LIDAR_DATA_FILE.exists():
+        unzip_file_from_archive_with_progress(
+            download_with_progress(LIDAR_DATA_URL, LIDAR_DATA_FILE.name), LIDAR_DATA_FILE.name, LIDAR_DATA_FILE.parent
+        )
+
+    if not TRAJECTORY_DATA_FILE.exists():
+        TRAJECTORY_DATA_FILE.write_bytes(
+            download_with_progress(TRAJECTORY_DATA_URL, TRAJECTORY_DATA_FILE.name).getvalue()
+        )
+
+
+# TODO(#7333): this utility should be included in the Rerun SDK
+def compute_partitions(
+    times: npt.NDArray[np.float64],
+) -> tuple[typing.Sequence[float], typing.Sequence[np.uintp]]:
+    """
+    Compute partitions given possibly repeating times.
+
+    This function returns two arrays:
+    - Non-repeating times: a filtered version of `times` where repeated times are removed.
+    - Partitions: an array of integers where each element indicates the number of elements for the corresponding time
+      values in the original `times` array.
+
+    By construction, both arrays should have the same length, and the sum of all elements in `partitions` should be
+    equal to the length of `times`.
+    """
+
+    change_indices = (np.argwhere(times != np.concatenate([times[1:], np.array([np.nan])])).T + 1).reshape(-1)
+    partitions = np.concatenate([[change_indices[0]], np.diff(change_indices)])
+    non_repeating_times = times[change_indices - 1]
+
+    assert np.sum(partitions) == len(times)
+    assert len(non_repeating_times) == len(partitions)
+
+    return non_repeating_times, partitions  # type: ignore[return-value]
+
+
+def log_lidar_data() -> None:
+    las_data = laspy.read(LIDAR_DATA_FILE)
+
+    # get positions and convert to meters
+    points = las_data.points
+    positions = np.column_stack((points.X / 1000.0, points.Y / 1000.0, points.Z / 1000.0))
+    times = las_data.gps_time
+
+    non_repeating_times, partitions = compute_partitions(times)
+
+    # log all positions at once using the computed partitions
+    rr.send_columns(
+        "/lidar",
+        [rr.TimeSecondsColumn("time", non_repeating_times)],
+        [rr.components.Position3DBatch(positions).partition(partitions)],
+    )
+
+    rr.log_components(
+        "/lidar",
+        [
+            # TODO(#6889): indicator component no longer needed not needed when we have tagged components
+            rr.Points3D.indicator(),
+            rr.components.Radius(-0.1),  # negative radii are interpreted in UI units (instead of scene units)
+            rr.components.Color((128, 128, 255)),
+        ],
+        static=True,
+    )
+
+
+def log_drone_trajectory() -> None:
+    data = np.genfromtxt(TRAJECTORY_DATA_FILE, delimiter=" ", skip_header=1)
+    timestamp = data[:, 0]
+    positions = data[:, 1:4]
+
+    rr.send_columns(
+        "/drone",
+        [rr.TimeSecondsColumn("time", timestamp)],
+        [rr.components.Position3DBatch(positions)],
+    )
+
+    rr.log_components(
+        "/drone",
+        [
+            # TODO(#6889): indicator component no longer needed not needed when we have tagged components
+            rr.Points3D.indicator(),
+            rr.components.Radius(0.5),
+            rr.components.Color([255, 0, 0]),
+        ],
+        static=True,
+    )
+
+
+def main() -> None:
+    parser = ArgumentParser(description="Visualize drone-based LiDAR data")
+    rr.script_add_args(parser)
+    args = parser.parse_args()
+
+    download_dataset()
+
+    blueprint = rrb.Spatial3DView(
+        origin="/",
+        time_ranges=[
+            rrb.VisibleTimeRange(
+                timeline="time",
+                start=rrb.TimeRangeBoundary.cursor_relative(seconds=-60.0),
+                end=rrb.TimeRangeBoundary.cursor_relative(),
+            )
+        ],
+    )
+
+    rr.script_setup(args, "rerun_example_drone_lidar", default_blueprint=blueprint)
+
+    log_lidar_data()
+    log_drone_trajectory()
+
+
+if __name__ == "__main__":
+    main()

examples/python/drone_lidar/pyproject.toml

@@ -0,0 +1,13 @@
+[project]
+name = "drone_lidar"
+version = "0.1.0"
+readme = "README.md"
+dependencies = ["laspy", "numpy", "requests", "rerun-sdk", "tqdm"]
+
+[project.scripts]
+drone_lidar = "drone_lidar:main"
+
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"