Dispatch from Support: Does Infraworks 360 Account for the Curvature of the Earth?

Infraworks does take into account the curvature of the earth, BUT it does not compensate for that when importing a large FBX or other 3D models. For example, I had a support case for a user that had a single FBX that contained an entire city's worth of buildings. He noticed that buildings far from the basepoint appeared to "float." It turned out that the ground had curvature but the 3D model did not. The workaround is to break up the 3D models into multiple pieces to avoid running into the curvature of the earth. 

engineering would be so much easier with a flat earth

The curvature of the earth also impacts Infraworks users if you are working in a custom coordinate system with Civil 3D. If you are used to Civil 3D, you may know that the curvature of the earth is completely ignored in any AutoCAD based product. If you are using an out-of-the-box, real-life coordinate system, the ellipsoid is taken into account when transferring data to Infraworks (e.g. adjustment to work with the curvature of the earth happens automatically). However, if you are working in a custom coordinate system in Civil 3D and are pushing it out to Infraworks there is no ellipsoid to adjust to, therefore you may see coordinate weirdness in large models.  

Custom coordinate systems make my brain hurt. I recommend avoiding them altogether, especially if you are using Infraworks. This goes double for large models, where you will see the effects of a curved Infraworks world.

Tschüss!