General Export Reference

  1. Supported Formats & Typical Usage
  2. General Export Options
  3. Formats Feature Comparison

Supported Formats & Typical Usage

Format Features/Typical Usage
Esri FileGDB Common file format for GIS workflows. Export to multipatch/multipoint/point/polyline geometry types into a File-Geodatabase. Textures are supported.
Wavefront OBJ The most compatible format. Transfer models with solid coloring or single texture layers to any DCC tool or rendering engine. Material definitions are exported into accompanying MTL files. Does not support instancing.
Autodesk FBX Provides export into Maya, Max, MotionBuilder and other DCC tools equipped with an FBX importer. Includes support for layered textures (multi-textures) and per-texture UVW transformations (scale, translation, rotation).
Collada DAE Exports into a large number of DCC tools and rendering engines with support for asset-instancing, layered-textures & file-referencing.
Keyhole KMZ / KML Exports into georeferenced earth browsers like ArcGlobe or Google Earth. Such models are shared e.g. in Google Warehouse.
CityEngine Web Scene (WebGL) Exports scene to a CityEngine Web Scene file (.3ws). CityEngine Web Scenes can be viewed in a web browser using CityEngine Web Viewer.
Esri Scene Layer Package Esri Scene Layer Package (.spk) is a custom, web-optimized format that can be shared on ArcGIS online and viewed with the WebScene Viewer.
Renderman RIB Direct export into any Renderman compatible renderer with support for delayed RIB loading, flexible shader calls and multi-texturing. For fast preview, CityEngine is able to generate additional RIB statements (camera, lights) in the master file and a phong-like template shader, which allow for direct rendering without the need for any additional scene-setup tools.
Alembic ABC Alembic is an open, high-performance interchange framework designed for VFX content production pipelines.
Script Based Export (Python) Allows for execution of arbitrary Python commands during batch export.


Export dialog for the FBX Model Exporter

General Export Options

These options are available for all export file formats. Certain formats contain additional settings which will be described in the corresponding section.

In the export wizard, each export option widget displays a tooltip with a description.

See below for a comparison of the different formats with respect to material and shading features.

General Settings

Option Description
Output Path Path to the export location. The path must exist.
Base Name The base name of the exported files. Various suffixes will be appended depending on the other export settings.
Export Geometry

Models with Shape Fallback (Default)
If model generation fails, it will export the start shape geometry.

Ignore the shape, if the model generation fails.

Only export the start shape geometry.


Terrain Layers

Do not export any terrain layers (Default)

Export all visible terrain layers

Export all selected terrain layers

Export all terrain layers


Simplify Terrains Uses the reduceGeometry CGA operation to simplify the terrain geometry prior to export. This can take a considerable amount of time, especially on higher resolution terrains - use with care.


Granularity Settings

Option Description
File Granularity

One file as long as Memory Budget is not exceeded
The geometry data is written into a single file if Memory Budget is zero, else Memory Budget is applied to the unoptimized mesh size and multiple files will be written.

  • The geometry size is measured on the raw meshes before any optimization. Therefore, the file size is usually smaller than the setting.
  • The check is performed per input shape not per rule output shape. I.e. very complex rules may generate more data than the limit setting.

One file per start shape
Exports one geometry file per shape.

Memory Budget Maximum geometry file size in megabytes. See remarks above.
Mesh Granularity

Do not merge any meshes
No meshes will be merged, each mesh will be optimized individually

Merge meshes by material
All meshes with the same material properties will be merged and optimized.

Reuse asset instances, merge generated meshes by material (Default)
Inserted assets/meshes (see CGA insert operation) will be preserved and instanced. Meshes generated by the grammar will be merged by material.


Geometry Settings

Option Description
Vertex Normals Allow (potentially smoothed) vertex normals or force flat face normals.
Normals Indexing Choose between indexed polygon normals or separated normal copies per polygon.
Texture Coordinates

Do not write any UV's
No texture coordinates will be exported.

Only write first layer of UV's
Only the first layer of texture coordinates will be exported (see CGA material attributes)

Write all UV layers
All layers will be exported

Local Offset

The local offset is computed for each individual shape.

None: Disable local offest

Model Centroid: use centroid of the generated model as offset,

Model Centroid Bottom: use centroid projected on bottom bound of the generated model as offset,

Shape Centroid: use centroid of the shape as offset

Shape Centroid Bottom: use shape centroid projected on bottom bound as offset

Local and Global offsets can be queried in the Script-based export callback methods.

Global Offset Global offset for generated geometry
Set offset for x, y and z axes (Cartesian coordinate values).
Vertex Precision These values can be used to reduce the floating point precision of different geometry data prior to the actual file output ( used to reduce file size in OBJ )
Merge ... within precision Coordinates (vertices/normals/texture coordinates) which have an euclidean distance equal or less than precision will be merged and their corresponding indices will be updated.
Triangulate Meshes Triangulate meshes after optimization.
Faces with holes

Write as holes (available for Collada only): Write the actual hole information.

Triangulate faces with holes: Triangulate the face with holes if the export format doesn't support holes natively.

Discard holes: Discard the hole information (ignore holes)

Convert holes to faces: Convert the holes to actual faces (creates coplanar faces)

Materials Settings

Option Description
Include Materials If enabled, material definitions (e.g. diffuse color) and textures will be included in the export (if supported by the format). Otherwise, the default material will be referenced (if required by the format).

Texture Settings

Option Description
Collect Textures All referenced textures will be exported into the export target folder and the file references will be adapted.
Create Texture Atlas Creates texture atlases which combine a set of textures into one, thus reducing the number of textures and materials.
All textures except COLORMAPs are removed.
Note: in case of repetition (i.e. uv coordinates outside [0,1]), textures can not be put into an atlas.
Texture Atlas Max Dimension (2^n) Specifies the maximal dimension of the texture atlases in power-of-2 pixels, e.g. 11 gives a 2048x2048 Atlas.
Texture Atlas Border Add a border of clamped pixels to protect against wrap mode bleeding.

Advanced Settings

Option Description
Write Log

Write log file with detailed information and statistics about this export session. In case of error, check the log file to find out what went wrong.

File Type

Choose among Binary or Text (ascii) based file creation.

Embed Textures Choose to reference the file path (Default) or embed the texture files within the binary file (FBX).
Shape Name Delimiter This character will be used to resolve clashes in the shape names. Example for delimiter "_": {"shape", "shape", "shape"} will be resolved to {"shape", "shape_1", "shape_2"}. Already existing suffices like "_1" will be recognized.

The name resolver can also be called manually on a selection of shapes via Edit → Make Names Unique....

Existing Files

Overwrite existing files
No file check is performed prior to writing the geometry files, all files are overwritten.

Skip existing files
Existing files (geometry, material and texture files) are not overwritten.



Option Description
Script Workspace path to python script for additional python execution parallel to export. (Only available for certain CityEngine licenses.) See Python Scripting Interface



Formats Feature Comparison

The features in this table are listed with respect to the actual output of the CityEngine, not the theoretical features of the individual format. Please also check the list with known interoperability limitations and issues in the application notes.

Format Instancing Shaders Multi-Textures Tex Trafo Triangulation Referencing
FileGDB No No No No Yes No
OBJ No No No No Yes No
FBX Yes (Note 1) No Yes Yes Yes No
DAE Yes No Yes (Note 2) Yes Yes (Note 3) Yes
KMZ / KML Yes No Yes (Note 2) Yes Yes (Note 3) Yes
3ws No No No Yes No No
spk No No No No No No
RIB Yes Yes Yes Yes Yes Yes
ABC Yes No (Note 4) Yes Yes Yes No

Feature Description:

The file format.
Support for instancing of geometry. Typically, the assets would be stored separately and in unmodified state from the actual nodes and transformation data.
Shader Names
Support for shaders
Support for multiple texture channels
Tex Trafo
Support for separate texture coordinate transformations independent from the texture coordinates stored in the meshes (eg. texture rotation).
Does the exporter support optional triangulation upon export?
Does the format support referencing of entities between files? This allows for the definition of a master file to combine all scene elements


Further Reading

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