skymodelr package
=================

Copyright (C) 2026 Tyler Morgan-Wall

The skymodelr package is distributed as a whole under GPL-3. The following
upstream copyright and provenance notices are preserved for attribution and
compliance with upstream notice requirements.

Bundled and downloaded third-party materials
============================================

1. Prague Sky Model implementation
----------------------------------

Files derived from, adapted from, or incorporating code from the Prague Sky
Model implementation by Petr Vevoda and collaborators:

  src/PragueSkyModel/PragueSkyModel.h
  src/PragueSkyModel/PragueSkyModel.cpp

Upstream project:
  https://github.com/PetrVevoda/pragueskymodel

Copyright/provenance:
  Copyright (c) Charles University
  Implementation repository and software by Petr Vevoda

2. Math utility code from Eric Bruneton
---------------------------------------

Files derived from, adapted from, or incorporating code from Eric Bruneton's
clear-sky-models project, including vendored files under:

  src/math/

Upstream source:
  https://github.com/ebruneton/clear-sky-models

Copyright/provenance:
  Copyright (c) 2015 Eric Bruneton
  All rights reserved.

3. ArHosek / Hosek-Wilkie sky model code
----------------------------------------

Files derived from, adapted from, or incorporating code from the ArHosek sky
model, including code based on files in:

  src/ArHosekSkyModel/
  src/hosek/

Upstream source used:
  https://github.com/ebruneton/clear-sky-models/tree/master/atmosphere/model/hosek

Original authors and copyright holders:
  Copyright (c) 2012 - 2013, Lukas Hosek and Alexander Wilkie
  All rights reserved.

Related papers:
  "An Analytic Model for Full Spectral Sky-Dome Radiance"
  "Adding a Solar Radiance Function to the Hosek Skylight Model"

4. Moon texture
---------------

Bundled file:
  inst/textures/lroc_color_poles_1k.jpg

Rights/provenance:
  Derived from NASA Lunar Reconnaissance Orbiter Camera (LROC) lunar image
  data. NASA-origin imagery is public domain in the United States.

5. Star catalogue data
----------------------

Bundled file:
  data/stars.rda

Source/provenance:
  Derived from the Bright Star Catalogue, 5th Revised Edition (BSC5), also
  known as the Yale Bright Star Catalogue. The source catalogue is commonly
  identified as Hoffleit, D. and Warren, W. H. Jr. (1991), "The Bright Star
  Catalogue, 5th Revised Ed.", Yale University Observatory, and is distributed
  as machine-readable catalogue V/50 by the Centre de Donnees astronomiques de
  Strasbourg (CDS):

  https://cdsarc.cds.unistra.fr/viz-bin/cat/V/50

  The package data contain derived stellar positions, apparent V magnitudes,
  spectral type strings, and computed RGB weights used for sky rendering.

6. Downloaded Prague coefficient data
-------------------------------------

Downloaded files:
  SkyModelDatasetGround.dat
  PragueSkyModelDatasetGroundInfra.dat
  SkyModelDataset.dat

Source/provenance:
  These files are not bundled in the source package. They are downloaded by
  download_sky_data() into tools::R_user_dir("skymodelr", "data"). The
  coefficient files are associated with the same Prague Sky Model project and
  copyright/provenance as the vendored Prague source implementation described
  above.

7. Configure helper
-------------------

Bundled file:
  tools/config.R

Copyright/provenance:
  Contains configure helper code from Kevin Ushey.

  Copyright 2017-2021 Kevin Ushey

  The upstream permission notice is preserved in the file header.
