Sky exposure factor

grasshopper ladybug-legacy
1

Hi,

I am using the ladybug view analysis to find out the sky exposure factor on a vertical facade. However, though the average value is acceptable, some of the result is higher than 0.5 (shouldn’t be larger than 0.5). I have checked the surface I selected and the distance from base (very low).

Anyone can solve my problem. Thanks.

2

Hi Ivan,
It would really help if you could share the bare minimum version of your file with geotries internalized please.

3

Sky exposure - test.gh (30.1 KB)

Thanks @devang. Please find attached the testing file I used. The sky exposure factor on facade is 52.4 in average. Thanks again.

4

@Ivanita,
Check te viewResolution_ input.
It will take more time to calculate but will be much closer to the 50%. This assumming you use the _viewTypeOrPoints 3 (sky exposure).
-A.

5

@AbrahamYezioro 's answer is correct. The view analysis component uses a ray tracing method that shoots out rays to find intersections with surrounding geometry and becomes more accurate when more rays are used. The default coarse tolerance will give you results that are +/- 3% increasing the resolution will drop this error further.

6

Thanks both @AbrahamYezioro and @chris for the clarification. May I ask if there is any document I can find for this?

Thanks again.

7

Most of the documentation for this is dispersed. This discussion talks a bit about the validation of the method and the difference between sky view and sky exposure.

There’s also the component descriptions that you can read on the gitbook here.

This recent tutorial video describes some of the ray tracing methodologies but you will only be able to view it if you are logged in as a Ladybug Tools patron. You can also buy the video itself here:

If we get enough patrons, hopefully, I can make this video free for all.
-Chris