This model contains some meshes created in Reality Capture
The textures show up in the viewport, but I can’t find the texture assignment in object properties nor layer properties. Object material assignment is ByLayer, and Layer material is Default.
Problem is when I render using vRay, the object comes out default and not as per the viewport.
There is no texture for that object. The colors that you see are assigned to the vertices of the mesh. The Rhino Rendered display mode will correctly show those colors. For rendering with the Cycles engine in Rhino 7 (using either the Render command or the Raytraced display mode), you will have to assign the Cycles VertexColor material to the layer or object. By default, that material is hidden but can be found after running the TestShowPrivateContent command.
But that only partially answers your question - I don’t know how V-Ray deals with this…
in order to render vertex colors in V-Ray you need to assign a material to the object of interest, that has a UVW texture in its diffuse slot. You also need to set the UV Channel to 0, which is the channel we use to export vertex colors to