Actual North Direction is opposite to the given North Direction

Hi all,

I am running a solar radiation analysis and when I do not give any direction for North. It takes the North as negative y axis (opposite to the default y axis). Also, when I give a vector for north direction, it reverses it and takes an opposite direction as North. I am really struggling with this issue that what is causing the reversal of the North direction.

Could you please have a look at it and guide me? Thank you so muchh!

You can see in the pic below th North direction is not regarded as the vector direction:

New users cannot upload attachments so I am unable to attach the GH file here. So, I am sharing the Google Drive link here:

Oh, I found out that it has to be flipped to keep the surface normals outwards. Could anyone please help me how I can test it and automatically flip the surface if its normals are inwards because I’ll be using many models and it will not be parametric to check each and every model.
Thanks a lot!

Hi Usman,

A closed polysurface always has normals facing outwards. If you use building massing as a guide for flipping the analysis surfaces that should solve your problem.

This image shows the surface normals before flipping based on guide surface, and the analysis result with the correct surface orientation.

Here’s a simple example script: (50.9 KB)



A simpler way to do this would be in Rhino to use the “Flip” and “Dir” commands to check your surface normals - the method above is just a way to automate that to a degree in GH

1 Like

That’s very cool Charlie. It works. Thank you so much :wink:

1 Like