Tutorial Notes – 05: Initial Shapes

A 3D shape results when z-values (elevations) are assigned to polygons.



As great a visualization tool that CityEngine is for the GIS world, other industries have platforms designed specifically for them.  If you are working in an interdisciplinary environment with architects, engineers or designers, others on your team will likely be working with Autocad3D Studio Max, Maya or Revit (all products of Autodesk), or maybe SketchUp. I’ve worked with people who use some of these platforms, but I know little else about them except a) they are out there and b) they are way better than CityEngine for certain industry-specific visualization tasks. But, since GIS is becoming a common ground in interdisciplinary efforts, you must know how to import files from these other platforms into CityEngine.

In this tutorial, we import shapes from a number of formats:

  • SHP – Shape files
  • GDB – Shape files from geodatabases: if there are a number of layers in the database, you will have the option of importing more than one
  • Polygons with z-values, which are three-dimensional shapes (in this case, a sphere), as seen in the illustration at the top of this page
  • OBJ – originally designed by Wavefront Technologies.  According to Archilogic, it is a commonly found format designed for importing/exporting geometry between different 3D visualization applications. They are stored in ASCII format.
  • DAE (Digital Asset Exchange) – used in COLLADA, another interchange file format. This one uses XML to describe data.

A full list of file formats that can be imported into CityEngine is available in the Help file under “Importing Data”; enter this term into the search window. There are support file formats for shapes, static models, graphs (streets), terrain and texture.

What you do with files in ArcGIS can help you in CityEngine

CityEngine will notice when you use certain field names in data tables (e.g. with shape files) including ruleFile and startRule,  and automatically assign these values to shapes.  In the illustration at the top of the page, note that when we selected one of the polygons, the parameters for ruleFile and startRule are already filled in.  This saves us from having to code these assignments for 205 polygons in any CGA rule file used with this data.

The statue of Ceres, the Roman goddess of agriculture, atop Chicago’s Board of Trade Building. This feature should be done as a static model and imported into CityEngine.

It is important to know the difference between shapes and static models.

According to the tutorial:

  • Shapes, such as footprints or building “volumes”, serve as a base for CGA generation, meaning you can apply rules to them, e.g. apply facades and colors.
  • Static models cannot be processed further with CGA. Why use something like this? Some design elements like statues are not best modeled in CityEngine — at least, I wouldn’t want to try. Some building models may come ready made and need no processing.

If we drag an OBJ or DAE file into the Viewport, the shape will be rendered as a static model by default.  If we want to work with these as shapes, we must RIGHT CLICK > Import and uncheck the box that says “Import as Static Model”.  This is known as “Import via Menu”.

Right-click > Import and leave the “Import as Static Model” box checked

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