So i have been having this problem crop up more and more and the last time it has happened it added at least 5 hours of work to fix the problem. Hope somebody can offer me some help.
So, i have been building the models as normal - ensuring as much as possible that the faces are forward facing etc. As i get towards the final stages with lighting and everything correct I will be doing multiple test renders and live renders. All that output correctly. Then potentially after I pick the model back up a day later, or as last night, set the computer to do some high resolution passes half of the model becomes invisible. Mostly single planes. But some elements such as glass suddenly has a second material in the back face (despite it not having anything other than glass on front and back faces).
This morning in order to fix it i have had to go into some of the materials and reflect then as there orientation had changed, some needed a simple inverted face, I had to add depth to some elements, remove depth from others. There seems to be varying solutions for different elements (glass for example, some had to be single faces, others could remain 10mm thick). Hence why it took hours to update the model.
What I don’t understand in particular is that this happens seemingly randomly, after multiple previous renders. The only thing i can think of that changed between the first renders and the second was I up’d the resolution and rendered with CUDA not just CPU.
Any advice would be much appreciated!