rendertime object swap (gsg tutorial)

[_Fertig]

Hi,

Iv'e recently been struggeling with C4Ds performance concerning many objects with heavy geometry, things becoming REALLY unresponsive. I had several bigger customer projects (clubs, restaurants, lounges, lots of upholstered furniture/chairs...). For me it's often not about picture-perfect renderings, but more conceptual stuff to quickly visualize ideas, mood of the room etc. Still, some detail is needed and especially sofas and some cushions can really bring the viewport performance down.

There seem to be several solutions:

1. bigger machine: ruled out because of budget
2. model optimization: works to some extent, but i honestly don't have the time to take a manufacturer model and spend half the day remodeling/reducing it, remapping textures etc.
3. xrefs: xrefs can be replaced with lowpoly versions in c4d and switched back to the highpoly xref for rendering (manually though, which can also cause your machine to hickup for a moment). I have to say I had a hard time with some xreffed materials not showing up and the switching mechanism breaking (so i had to reimport everything, not catastrophic, but also not nice)

4. the alembic file format:

I stumbled upon a greyscalegorilla tutorial ( http://greyscalegorilla.com/tutorials/r ... ap-in-r17/ ) the other day, suggesting to use the rendertime replacement option of an imported alembic file (merged). The magic goes somewhat like this: take a highpoly model, use the polygon reduction modifier and bake the current state to object. Save both versions to separate alembic files, but only import the lowpoly version into your file. The highpoly model is only called upon rendertime, but apparently never gets imported into the file, resulting in a lighter file and thus better handling. Materials can be applied through polygon selection sets (shown here: https://www.youtube.com/watch?v=nqbT-3tjxtg ), it's a bit of a hassle though, as the alembic format doesn't include material information.

I did a small scale test, which worked out with some adjustments (object identifier needs to be set by hand, the "render instances" box in cloners doesn't work, you have to place an instance into the cloner). The big advantage to me is, that I can work with really light geometry, and don't need to switch around/toggle visibilities. Now live viewer renderings show the lowpoly version, which is usually enough to set the lighting etc. Test renderings in the picture viewer show the detailed model.

Maybe I'm telling you old news, maybe someone finds it useful for themselves, let me know.. I'll thoroughly test it on the next bigger occasion and update this if necessary.

Best,
Lukas