TPPSS computes sunrise / sunset times taking into account local topography provided by the user as a DEM (it can also simply compute an horizon based on the DEM). It provides a library and a command line script to compute sunrise / sunset for a location for a single day or a whole year.
The tool requires Python 3.7+.
To install just the library, launch:
pip install tppssDepending on your Python version and platform , the rasterIO library may not be available in binary form on PyPI. It is recommanded to use Conda to first create an environment then install TPPSS with:
conda install -c conda-forge rasterio
pip install tppssThe second command will pick up the rasterIO installed by Conda.
The cli extra includes a command-line script, also named tppss, whose functionality is described below. It has a few additional dependencies.
Launch:
pip install tppss[cli]The library documentation is available here. (not yet)
The tppss tool has 2 subcommands:
dayyear
The day subcommand prints to the console the sunrise and sunset times for the chosen day.
~$ tppss day --help
Usage: tppss day [OPTIONS]
Compute sunset / sunrise time for a single day
Options:
-p, -position LATLON Latitude and Longitude of the location to
consider (eg 45.2315,5.8389) [required]
-m, --dem FILE DEM in TIFF format and Geographic CRS (eg WGS4)
[required]
-j, --day DATE Date to consider (in YYYY-MM-DD format)
[required]
-t, --timezone TEXT Timezone for the result [Default: Timezone of the
local machine]
--distance INTEGER Distance from the position to consider when
computing the horizon (in KM) [default: 25]
--angle-precision INTEGER Precision of horizon angles (for each degree)
[default: 1]
--time-precision INTEGER Precision of times (for each hour) [default: 60]
--help Show this message and exit.tppss day -m "C:\Users\gvellut\Documents\projects\sunlight\rge74_wgs84_cubic.tif" -j
2021-11-01 -p "46.179317,6.234106"
It outputs:
Timezone set to local: 'Romance Daylight Time'
Compute horizon...
Compute sunrise / sunset...
Sunrise: 2021-11-01 07:47:00+01:00 / Sunset: 2021-11-01 16:21:00+01:00
The first line is a warning indicating which timezone was selected, since none was indicated on the command-line. 'Romance Daylight Time' is the name of the local timezone on my Windows computer.
In case there is no sunset or sunrise (maybe in a location surrounded by high mountains or above the arctic circle), the last line is either: Light all day! or Night all day!.
The year subcommand outputs to a CSV file the sunrise and sunset times for each day of the chosen year.
~$ tppss year --help
Usage: tppss year [OPTIONS]
Compute sunset / sunrise time for a whole year
Options:
-p, -position LATLON Latitude and Longitude of the location to
consider (eg 45.2315,5.8389) [required]
-m, --dem FILE DEM in TIFF format and Geographic CRS (eg WGS4)
[required]
-y, --year YEAR Year to take into account [required]
-t, --timezone TEXT Timezone for the result [Default: Timezone of the
local machine]
-o, --csv FILE CSV to export [required]
--distance INTEGER Distance from the position to consider when
computing the horizon (in KM) [default: 25]
--angle-precision INTEGER Precision of horizon angles (for each degree)
[default: 1]
--time-precision INTEGER Precision of times (for each hour) [default: 60]
--help Show this message and exit.tppss year -m "C:\Users\gvellut\Documents\projects\sunlight\rge74_wgs84_cubic.tif" -y
2021 -p "46.179317,6.234106" -t Europe/Paris -o ss2021.csv
It outputs to the console:
Compute horizon...
Compute sunrise / sunset for year 2021...
Writing results to C:\Users\gvellut\Documents\projects\github\calcsoleil\ss2021.csv...
The CSV is as follows:
DAY,SUNRISE,SUNSET
2021-01-01,08:48+0100,13:59+0100
2021-01-02,08:47+0100,13:59+0100
2021-01-03,08:47+0100,14:01+0100
2021-01-04,08:46+0100,14:04+0100
2021-01-05,08:46+0100,14:04+0100
2021-01-06,08:44+0100,14:05+0100
....
The times for sunset and sunrise also indicate the offset from UTC (which can change in the year with DST).
If there is no sunset or sunrise, the second and third columns have value NA.
The Latitude and Longitude must be in the same CRS as the DEM.
The DEM (Digital Elevation Model) raster must contain heights above the ellipsoid. If the DEM contains instead the altitude above the geoid (for example, EGM96 if SRTM is used), it should first be transformed into heights. However, since only differences of altitudes are considered, it shouldn't matter much depending on the specific purpose (I use this tool for planning photography outings and I am fine with the precision I get). If needed, the ellipsoidal heights can also be computed using GDAL (gdalwarp: See the example at the bottom of this page).
The value for the timezone option is something like Europe/Paris or MST. If not present, it is taken from the local machine. If the timezone has DST, the change is reflected in the times computed for surises and sunsets.
The --distance option indicates how far away from the position should heights be extracted from the DEM when computing the horizon.
The horizon computation is based on this Matlab code (adapted for Python + Numpy):
Benjamin Pillot (2021). DEM-based topography horizon model (https://www.mathworks.com/matlabcentral/fileexchange/59421-dem-based-topography-horizon-model), MATLAB Central File Exchange. Retrieved October 19, 2021.
The sun position computation is adapted from this code:
John Clark Craig. Python Sun Position for Solar Energy and Research (https://levelup.gitconnected.com/python-sun-position-for-solar-energy-and-research-7a4ead801777)
- Example that draws horizon + sun course through the sky
- Support projected CRS (use vertical compensation see https://www.usna.edu/Users/oceano/pguth/md_help/html/demb30q0.htm)
- Generate doc
- Sample: Document how the input DEM is obtained from the RGE
- Optional Rasterio dependency for CLI ; separate CLI dependencies from the library
- Conda package