Current version: 0.2.8 (alpha)
ear ye, hear ye! The mysteries of the universe have been unraveled! No longer must you manually set the time of day, wondering if your settings are correct or not. No longer will you have to suffer while creating a day/night cycle. USPA is here to save you from these wretched curses.
What is it?
USPA (or Unreal Solar Position Algorithm) is a plugin that automagically converts date, time and location (latitude and longitude) to an actual solar position with an accuracy of +/- 0.003 degrees! That’s crazy, huh? It’s based on National Renewable Energy Laboratory’s own solar positioning algorithm.
How’s it different from anything else?
First of all, USPA is a highly accurate algorithm that takes into consideration not only date, time and location, but also:
Fractional second difference between UTC and UT which is used to adjust UTC for earth’s irregular rotation rate.
Difference between earth rotation time and terrestrial time.
Annual average local pressure.
Annual average local temperature.
Surface azimuth rotation.
Atmospheric refraction at sunrise and sunset.
It also outputs not only the sun’s position, but also:
Earth’s heliocentric/geocentric longitude, latitude and radius vector.
Mean elongation (moon-sun), anomaly (sun/moon), argument latitude (moon), ascending longitude (moon)
Greenwich sidereal time and mean sidereal time.
Sunrise/sunset time and angle.
Topocentric sun declination, right ascension and local hour angle.
And much more.
Why do I need it?
Why don’t you? If all you want is some boring ol’ directional light moving across the sky with whatever position, then USPA is not for you. But if you want highly accurate sun/moon position with a boatload of features (see above), then USPA is for you.
Can I see it in action?
February sun transit:
July sun transit:
Setting it up is also a breeze. Just input a few parameters and presto!
Where can I get it?
Currently, USPA is in alpha state and is still being worked on. I’ll update the OP when it’s released.
Can you add X feature?
I’m generally open to all suggestions. Just shoot and I’ll see what I can do.