HaloViewer

A viewer and plotting toolkit for Halo Photonics wind lidar data (.hpl files) covering the processed-product tree (Proc/YYYY/YYYYMM/YYYYMMDD/*.hpl). Every kind found there is plottable: the instrument-processed Processed Wind Profile (a single scan's height/speed/direction profile, or many combined into a height/time History image), and the raw regular-scan kinds -- VAD, Stare, Wind Profile and RHI -- each of which gets a distance/time intensity+beta History image built from their raw per-gate data (no instrument-processed profile of their own), plus two single-scan views of radial velocity and beta: RHI (the scan's points projected onto the vertical plane along the first ray's azimuth) and PPI (projected onto the horizontal plane), each drawn as dots or, optionally, filled by inverse-distance-weighted interpolation. Any other kind found on disk is still listed (so you can see what's in your data tree) but reported as not yet implemented.

Installation

Conda (recommended -- minimal footprint on top of miniconda)

conda env create -f environment.yml
conda activate haloviewer

This only adds numpy, pandas, matplotlib and scipy on top of a base Python; the GUI toolkit (Tkinter) ships with the standard python conda package on Linux, macOS and Windows, so nothing extra is needed for the GUI itself. Tested against Python 3.9+ on Ubuntu 22.04, 24.04 and 26.04, macOS and Windows.

Plain pip

pip install -e .

(On some minimal Linux distributions Tkinter is a separate OS package, e.g. sudo apt install python3-tk on Debian/Ubuntu -- not needed when using the conda environment above, since conda's python package already includes it.)

Version numbers

The version is derived from the git history by setuptools-scm and written to haloviewer/_version.py when the package is installed. To make a release, tag it (e.g. git tag v0.2.0) and reinstall. Without git metadata (e.g. installed from a zip) the version falls back to 0.1.0. Static project information (author, licence, ...) is in haloviewer/_metadata.py.

Contents

HaloViewer provides four ways to work with the data. Each has its own page in the full documentation (see below).

Graphic viewer -- haloviewer. A Tkinter desktop application for browsing a Proc tree: pick a directory, a file kind and a plot type (Profile, History, RHI or PPI), then step through single files or whole time windows, with adjustable height, distance and speed ranges.

haloviewer /path/to/Data/Proc

Command-line tool -- haloplot. Plots files, directories or glob patterns straight to an image file, without the GUI. File kind, plot mode and time range are inferred where possible and can be set explicitly.

haloplot Proc/2026/202609 --kind RHI --start 24h -p rhi_24h.png

Sync tool -- halosync. A separate GUI for selectively copying the Metek, Proc and Raw trees from the lidar control PC to a backup or analysis disk. It skips files that are already there, leaves out the file the lidar is still writing, and can run on a fixed schedule.

halosync

Python API -- haloviewer.plot(). The same functionality as haloplot for scripts and notebooks. It returns a matplotlib Figure for further customisation.

import haloviewer
fig = haloviewer.plot("Proc/2026/202609/20260919",
                      kind="Processed_Wind_Profile", start="24h")

Documentation

The full documentation (Sphinx, in docs/) describes each tool in detail and includes the API reference generated from the docstrings. Build it from the project root; the HTML ends up in build/html/:

pip install -e ".[docs]"
sphinx-build -b html docs build/html

Design

File structure

The code is layered so each piece can be used, tested and understood on its own:

plotting.py never imports tkinter, and gui.py never calls matplotlib drawing primitives directly -- it only calls functions in plotting.py. This means the exact same plotting code is used by the GUI, the CLI, and any script that imports haloviewer.api.

Extending to more scan kinds

Processed_Wind_Profile, VAD, Stare, Wind_Profile and RHI are all implemented; a user-defined pattern (User1...User5 in the raw .hpl header's Scan type) or a future Halo scan kind would follow the same recipe:

1. Add a reader to data.py that turns a parsed hpl.DataFile (or a set of them) into plain arrays. A regular scan file can usually reuse load_scan_history and load_scan_points as they are.
2. Add drawing function(s) to plotting.py that take those arrays and axes/figure objects -- reuse create_timeseries_figure's two stacked, colour-mapped panels (all History flavours) or create_scan_pair_figure's two side-by-side panels (the RHI/PPI views) if one of those shapes fits.
3. Register the kind's capabilities in scan.KIND_CAPABILITIES (supported=True, its plot modes).
4. Wire the new mode(s) into api.plot_file/plot_files, and into gui.HaloViewerApp._plot_kind (which of the five load/render pipelines applies) and _update_range_controls_enabled (which of Height/Distance/Speed/Fill make sense for it).

The GUI will then automatically offer that kind and mode as soon as it is discovered on disk -- no other GUI changes are needed.

Tests

pip install -e ".[dev]"
pytest

Licence

HaloViewer is licensed under the European Union Public Licence v1.2 (EUPL-1.2); see LICENSE for the full licence text.

haloviewer/hpl.py is adapted from the hpl module of cdruee/python-readmet, which is itself licensed under the EUPL-1.2.

Copyright

(c) 2026 Clemens Drüe, Universität Trier

Developed with support of Anthropic Claude Opus 5.5.