Sky View simulation results are strange when target building geometry is not included as part of the context

Dear bee and bugs,

I got some strange results when the target building geometry is not included as part of the context geometry for the Sky View simulation using the View Analysis component:

There is no such problem when using the same workflow for Sky Exposure simulation.

I assume the target building itself will be automatically included as part of the context geometry due to consideration of self-obstruction …

Hope you can kindly advise!



target building is not connected to “context” input node:

target building is connected to “context” input node:

view analysis problem (1010 KB)

Hi Ji,

There is an input that lets you control the self-obstruction of your geometry.

For more information, take a look at this short discussion:




Thanks, Antonello, for the clarification!

But, isn’t this option is set to “true” by default for view type 3 and 4?

Hope you can kindly advise.

  • Ji

Hi Jin,

you are right, we should modify a couple of code lines. Thanks



Thank you very much, Antonello!

It’s really just about one line of handy code …

Ji and Antonello,

Thank you very much for finding this bug. I can’t believe that I made a mistake as simple as putting a “<” when I should have put a “>”. So the component was actually doing the opposite of what I said it was in the description.

In any case, I have fixed this on the github now and in the attached file.…

Thank you again!

-Chris (1.33 MB)

Thank you very much, Chris, for the prompt fix!

  • Ji

I want to use this post to show the results of SVF calculation in two distinct city areas:
The first is correct:

In the second, the SVF is not defined properly:
In this second area the avg, st. dev. and min/max of the recorded values are as follow:
A negative value of SVF is not possible.
Why it happened? How can I solve?

Can it be related to the normal direction of the surface?

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@Francesco661 I’d agree with @AbrahamYezioro 's suggestion.

Also, FYI that for surface-based Sky View Factor or Sky Exposure Factor calculation, pls set a very small distance between the test points and the target surface, like 0.01m or even smaller, to avoid getting zero values when the test points are located right on the surface, or getting overestimated values for test points on vertical surfaces that are positioned very close to the top edge of the surface.

1 Like

Thank you @Grasshope and @AbrahamYezioro for your correct suggestions. I simply solved considering: Surface>Utilities>Flip