topic Re: City Engine Roof Orientation in ArcGIS CityEngine Questions

City Engine Roof Orientation

TianyiWang1 — Wed, 10 Jun 2020 21:03:42 GMT

Hello all, I'm trying to map an European town with many sloped roofs in City Engine. The rule I use is the default one: Building_from_OpenStreetMap.cga. The roof ridge generated for buildings seems like always along the building's longest side, however I wonder if there is a way to control the roof orientation. For example, In the picture below, how to make roof 1 run the same direction as roof 2?

I have manually run "Set to first edge" and "Compute first/street edge" tools for this building, but the roof doesn't change at all. (I set the edge computing to the shortest side but it doesn't work). Any suggestion could be helpful cuz I'm still new to this. My CityEngine version is 2019.0.

Re: City Engine Roof Orientation

CherylLau — Tue, 16 Jun 2020 17:43:40 GMT

To control the orientation of a roof, you can select an edge of your building footprint and go to Shapes -> Set First Edge. This will only have an effect for shapes with Roof_Form = {shed, gable, half-hip, gambrel, saltbox}. This cannot be done for dynamic shapes (shapes automatically generated by street networks). It looks like your shapes have gable roofs, and if they are building footprints from OpenStreetMap, then they are not dynamic shapes, so this should work for you.

Re: City Engine Roof Orientation

TianyiWang1 — Tue, 16 Jun 2020 22:00:00 GMT

Hello Cheryl,

Thanks for your reply. My buildings are downloaded directly from OpenStreetMap, but no matter which edge set to be the first edge, the roof direction won't change at all. Do you have any idea why this happened?

Tianyi

Re: City Engine Roof Orientation

CherylLau — Fri, 19 Jun 2020 11:15:04 GMT

No, sorry, I don't know why it doesn't work for you. It works for me.

Does it work on a rectangular footprint that you draw yourself?
Is the front edge actually changed? When the shape is selected, the front edge of a shape is partly orange to distinguish it from the other edges.
Is the Roof_Form set to something that will change (like "gable")?