CityEngine Unreal Exporter FAQ

Document created by BNeukom-esristaff Employee on Apr 5, 2018Last modified by BNeukom-esristaff Employee on Jul 19, 2018
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This FAQ should answer some common questions regarding the Unreal Engine exporter in CityEngine 2018.0.


  1. Is CityEngine available for testing/educational purposes right now?
    Yes, a trial version of CityEngine 2018.0 (includes the Unreal exporter) is publicly available here.
  2. What are the system requirements for creating a large scale project like the HOK Planning Demo project shown in the Webinar?
    We recommend 32G memory, Nvidia 980GTX or 1080GTX GPU (or AMD equivalent) and a current i7 (or AMD equivalent, like Ryzen) CPU.
  3. Can the exported Unreal project be shared or is this only for design purposes?
    All Unreal features are available, i.e. you can easily export to a shareable standalone "game" executable.
  4. Is this model (the HOK Planning Demo from the Webinar) lighted by stationary lights? I mean, there isn't any lightmass calculation?
    The HOK planning demo was done with dynamic lights (and was still very fast). Light map baking via lightmass is tricky to get right on large city scenes (also quite slow).
  5. How do you deal with Frame rate and optimization if you need to share this executable with a client? It seems like exporting it straight out of City Engine will spike the frame rate.
    The demo shown in the webinar was a straight forward export out of CityEngine with more than 100million polygons. In CityEngine we only spent a bit of time to make sure we not generate more materials than necessary (this is the expensive part in Unreal). We still achieved 60fps on a Nvidia 1080GTX.
  6. I was wondering if that project is available to download, so I could check the blueprint logic involved in that process.
    The initial release of the Unreal exporter will only contain the template project with CityEngine materials and a basic tutorial. In the next few months we plan to release more involved projects...
  7. How is the lighting handled, built-in or preview mode and how does it work over 10's of km?
    The webinar demo scene covered about 10x10km consisting of about 100million polygons and is using dynamic lighting (no lightmap baking). On a Nvidia 1080GX we reached 60fps with this setup.
  8. Is there a standard price for CityEngine? And if so, what is the price for CityEngine?
    CityEngine pricing depends on your local Esri reseller, please find contact information in your country here.
  9. I cannot find the CityEngine Template Project in the Epic Marketplace!
    Users with an Unreal Studio license should automatically see the "Unreal Model Loader" project in the Vault section of the Epic Games Launcher.
  10. Why are the tree models (in fan/model representation) from ESRI.lib not displayed correctly in Unreal?
    Our default material in the template project does not support opacity masks for performance reasons. The trees in model/fan representation in ESRI.lib make havy use of opacity masks, so the material needs to be adjusted. In CGA, the material used in Unreal is controlled with the "material.shader" attribute. There is currently a limitation in ESRI.lib that this attribute cannot be set from the outside, i.e. we recommend to create a modified copy of ESRI.lib for use with the Unreal exporter. Please modify these two rules in "Plant_Loader.cga":

    const UE_M_MASKED_OPACITY = "/Game/Materials/CityEngineMaterials/M_CE_MaskedOpacity"
    PlantModel(scaleY,scaleXZ,relOffsetX,relOffsetZ) -->         
      // ...          
      set(material.shader, UE_M_MASKED_OPACITY)         

    PlantFan(scaleY,scaleXZ) -->         
      // ...         
      set(material.shader, UE_M_MASKED_OPACITY)         

    Known Issues and Limitations

    1. Any "builtin" textures like "builtin:default" and "builtin:uvtest.png" are currently ignored at export (CityEngine 2018.0).