Why do i need to import the Shaders required by the Crowd Characters in the Render Scene ?

When the render starts, the rendering engine translates the Maya rendering scene in its own file format (.vrscene for V-Ray, .ass for Arnold...). Thus, as shading assignment is simply done by attaching a Shading Group / Shader name to a Mesh, the required Shading Group / Shader nodes need to be translated as well in the rendering engine file format. To do so, those Shading Group / Shaders need to be imported in the scene and assigned to an active geometry (not hidden). If they are not assigned or assigned to an hidden geometry, the rendering engine optimizes the translation and ignores the nodes. To make sure your dummy geometry will be not visible at render time, you can deactivate its Primary Visibility or move it far for the camera frustum.

Hence, there's no need to save Shading Group / Shader along with the Geometry File (.fbx). The Geometry File is only used to compute geometry information (skinning, blendshapes, geometry caches...). Moreover most shaders (like custom renderer shaders) can not be saved in an Fbx file.

Thus the usual workflow is:

• do the LookDev for Character AA (geometry, skinning, shaders...) and save it in a maya scene (lookDevAA.ma)
• create the corresponding Golaem Character and export the relative Geometry File (.fbx)
• do your crowd simulation in an another maya scene (crowdSim.ma)
• when creating a Render Proxy, you're prompted to import the Crowd Character Shader Groups / Shaders: import the lookDevXX.ma file of each Character used in the crowd scene so its shaders become available