If you import say a curve or an arc into CityEngine it always gets chopped up into short segments with control points and straight segments in between. This creates various problems within CityEngine that cannot be foreseen or are not repairable without manual intervention.
We have tried a lot of different ways to import splines from the formats available to CityEngine but no luck so far. Most of the time we must redraw the streets manually within CityEngine with its own spline tool and that is not economically viable on that scale that we need. The only time we actually seemed to get splines was using FileGDB however that unfortunately turned out as a multidimensional spaghetti (see attached images). Is it possible to successfully import spline graphs into CityEngine and does anyone have a good pipeline for that? Streets are such an important part of CE and I hope there is a solution!
We are a team working with CityEngine as one of our main tools for generating 3d-models for urban planning using GIS-data and automation means everything to our productivity.
That spaghetti is what I always get from importing OSM streets. I have also never gotten a spline drawn in ArcMap into CE (neither in SHP nor GDB format) without losing the curve. In fact I have never gotten a curve at all unless I densified it beforehand (and so turned it into a collection of straight segments).
That aside, street creation is an absolute nightmare in CE, especially if you have even slight terrain elevation to deal with. Look up Infraworks, that's how you properly handle street creation.