Rhino sun position accuracy

Hello,

I had to investigate the sun hours received by the house in a certain location. I run the calculations in ladybug which revealed that the surrounding buildings do not affect the sun hours in the examined period.

I wanted to create the visualization showing the shadow at chosen hours of the day.

And here is my problem: Rhino sun shows that the buildings DO affect the house by taking 12 minutes from sun hours.

The same visualization made in the unreal engine shows that shadow does not “touch” the building.

However, the difference in the shadow’s positions is huge.

Rhino

Unreal engine

Why the difference is so big and whom I should trust?

I don’t know what this means.

I’m not familiar with Unreal in this aspect, but in your second screenshot he Unreal SunSky location has a north offset of 270. That sounds incorrect to me. Any reason to not have it at 0°? (360°).

Also ensure your time and date is entirely the same. In Rhino you don’t have daylight saving checked. You can see that UTC is 16:00 and local time 17:00… It appears you have timezone +2,0 in Unreal, whereas in Rhino it is with your current settings +1.

We ran internally some numbers on the sun location just the other day. Inputting our location data and the numbers Rhino generates correspond with other sun location calculators. I’m inclined to trust Rhino over Unreal.

Thank you @nathanletwory for your answer.

Sorry, I will provide additional information. I was checking the sun hours from 7:00 to 17:00 (5 p.m.) local time. I noticed that from 16:48 (4:48 p.m.) the shadow starts to cover the window. Thats why I said that Rhino sun shows “taking” the 12 minutes of sunlight.

My model and its orientation toward the north comes from a drone survey with the use of real-world coordinates. In short: in Rhino the Y-axis is north. In Unreal, I rotated the north by 270 degrees to match it with the model Y-axis. So both “Norths” are facing the same direction.

Before, I thought that “daylight saving” is some graphic function. After reading your comment I dug into the topic and found that this is the root of my problem. After checking “daylight saving time” in Rhino and Time Zone to 1 in Unreal, both programs show the same position of the shadow.

Rhino

Unreal

I am very grateful for your help. I was worried that something may be wrong with my calculations.

I’m glad you figured out the solution.