In order to try and speed up the rendering phase I am looking into how I can use rendering farms like RenderRocket. Since CineRender in AC18 lets you export to Cinema 4D I would expect to be able to render using the service. I don't personally own Cinema 4D so I haven't tried that myself.
RenderRocket lets you upload a *.C4D file and all assets (textures, etc) you use in that project. But AFAIK these assets are built into the ArchiCad project and/or libraries, so when I tried just rendering using the C4D file the render failed with a list of textures missing:
I looked in the Surface Catalog 18.lcf, and found one of the textures (Fabric GS.jpg [not .png]), so you should try the Extract a Container... command, which unpacks the .lcf file, to be able to get and copy these texture files (I don't think the operating system can search the .lcf files). You should also look in the Embedded Library.
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@zgeorgievg: yes and no. as David said, I could find some references in the Catalog files that had the same name (but wrong file extension). as long as the names don't match up, and it's such a pain to see what is added manually and what is in the embedded files, it's a bit too hard.
But yes, I did get to extract the files. It was really easy, so I have no idea why you ended up with gsm files. Try googling "extract catalog archicad" and you should find a guide.
I really wonder why the image files show up as PNG in Cinema 4d files, but JPG in the embedded files ...
The various catalogs contain different asset types. I see that you have extracted assets from the furnishings catalog, so the GSM files are probably 3d models. Other catalogs will probably contain other files, like textures for trees, etc.
Someone else should answer this, as I don't have access to AC atm.
Do you have a folder called "tex" at the file location where you have your c4d file exported from ArchiCAD?
Normally, you should see this folder next to the c4d file and this folder contains the texture images in PNG format.