About SkyDome Visualization

Hello forum,

When I work with Skydome component I can’t but notice the irregularities in the patches, especially when using Reinhart model. For example (image), in the middle of sunny July there are suddenly some blue patches (low solar radiation). I understand it as the day being cloudy or rainy (for several days even), since single patch displays a a number of days, there are sometimes, occasionally, cloudy days that just happen to appear on one patch, thus such irregularity.

Since data is collected throughout the decades on a physical equipment, there is no way sky dome can show sunny days during the whole year (unless it is in Sahara or somewhere)

These are, of course, just guesses, I would like to hear some knowledgeable opinion on topic to be super sure.



What you are running up against here is the resolution of sky patches for the Reinhart sky being finer than the hourly resolution of sun positions. You can find a full account of this type of issue on this discussion:



One minor comment. The sky is cumulative that can be confusing. If you want to study a single day then you should generate the sky only for the day that you’re interested. Have you tried to use selectSkyMtx to generate the sky for a single day?

Hi Mostapha,

Yes, I always use selectSkyMtx, just don’t set the time boundaries. I’ve set them just to check and got results that are even more confusing. Now direct solar radiation doesn’t show any value and legend values are too small.

CHN_Shanghai.Shanghai.583620_CSWD.epw (1.69 MB)

Hi Tim,

Back to values when you use only an hour the values are going to be much smaller because that’s only the value for a single hour. The one that you’re showing up there is a cloudy hour and sky is pretty diffuse.

I made a gif file that I hope for better understanding of the cumulative sky. I generated the sky for 20 July in Chicago between 7 am and 5 pm. On the left you see the sky for each hour and you can see how the radiation values of the sky are assigned to sky patches for each hour. On the right you can see how cumulative sky gets built based on values for each hour for a single day.

click on the image to see the animation