PBR name connection & material.opacity

02-18-2020 05:10 AM
Occasional Contributor II

Hi, I wanted to figure out how the PBR materials works, with maps was included etc. and how to get automate the assignment of a material catalog with PBR materials.

So my first question, why is my export not honoring opacitymap, how should the CGA look to get the opcatiymap included? In CE it looks as it should, but export to FBX or DATASMITH, I just get a full metal plate 


What is the trick, that I've never figured out? I know that we did something with the template Unreal project and the rule, but as I understand, that should not be needed anymore.  

Second question:

I see a lot of different maps around, that could maybe be a part of PBR. Sometimes it matches perfectly into CE, but sometimes it don’t:

Some material attributes are designed to be exclusively used for physically-based rendering shaders. These are:

  • emissivemap
  • occlusionmap
  • roughnessmap
  • metallicmap
  • emissive
  • metallic
  • roughness

If the shader name is set to "CityEnginePBRShader", encoders which support PBR materials use those attributes as well as the

  • color
  • colormap
  • opacity
  • opacitymap
  • normalmap


For my eye it seems that there is a lot of different names, but the texture looks the same to me. I’ve tride to find documentation on google to figure out when to use what, and if something could be replaced by others

Sometimes I get a Diffuse or displacement maps, how do those guys fit in? Sometimes I also have a mask map. All the materials I get, are from sites that say PBR materials, like quixel or CC0 materials. Could someone please help me translate or understand the different maps out there?

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1 Reply
Esri Contributor

Hi Kenneth  

First about the opacity thing. With CityEngine 2019.1 (which one are you using?) the Unreal export should automatically choose the right "opacity mode" for you, so you actually should not need to do anything special in CGA.

But, if you are setting material.shader to some shader path in Unreal (like "/Game/Materials/CityEngineMaterials/M_CE_Opaque") or you set the opacitymap.mode to opaque the automatic opacity mode selection is not triggered anymore. 

If you think you did everything right you can also send me a zip of your project so I can have a look  

About the PBR (specifically for Unreal). Typically what you are interested in are the roughness map and the metallic map (here is a good description: Physically Based Materials | Unreal Engine Documentation) in combination to what you typically use like diffuse (which is the same as the colormap in CGA), normal and opacity maps. Let me know if you want to know more.



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