MESH of complex geometry

[sophie Lu]

Hello,

I want to process complex urban ground as a MESH simulation. Now I have generate MESH of buildings successfully from DSM file. In this case, how can I extract the air area above the city? I have tried to generated a box that can cover the buildings and do Boolean cut, but it always warning that "cut cannot produce".

Is there any reference example or suggestion?

Thanks for your help!

Sophie