Accuracy of the sun & sky model.

[J_Seg]

Hi!

I'm using vray physical sun and sky to simulate how the sun moves during the day in my architectural projects, using latitude longitude and date. One of my clients recently questioned the accuracy of the renders based on this approach. I have to pass the question on to you guys who made the software. This may be a big and difficult question to answer but how accurate is the sun and sky? I guess it is based on a phisical model of some sort.

Another related question, does it take into account the daylights saving time?

Regards J.

[vlado]

The sun and sky models are based on data in the references at the end of this page: http://help.chaosgroup.com/vray/help...htm#references

The position of the sun itself is based on the following publications:

http://www.amazon.com/Practical-Astr.../dp/0521356997
http://web.archive.org/web/200602061...epler/sun.html
http://web.archive.org/web/201109270...r/sidereal.htm
http://web.archive.org/web/200307301...0009/0068.html

You can contact the authors of the respective publications to inquire about their accuracy.

Other than that, of course I don't exclude the possibility for errors in the implementation. If you can explain a bit exactly what makes you doubt the results, it will be very helpful.

Best regards,
Vlado

[snivlem]

In the very early days of V-Ray for Maya the sun was actually wrong.

But they fixed it years ago (like 2009 from memory).

I've done several tests comparing to other programs like VectorWorks Sun system and also SketchUp's sun system. Maya and V-Ray match both programs perfectly. It is correct.

I've even matched real world built projects taken with a photograph to our 3D Cad models and V-Ray cam standing in the same position. V-Ray Sun + Sky matches the photographs as well.