Open object Render issues

[tourit_media]

One of our 3D Artists noticed the other day their render times jumped form around 30 seconds to 4 minutes a frame when they added a metal material to object in the scene. Upon further investigation we found it wasn’t the metal shader that was the problem but the fact that a metal shader was applied to an object that was open on the back. The image attached is the same exact setting renders on a Titan RTX, but the only thing different is the louvers back was bridged instead of being open. I should also mention that the inside of this building is empty and has no light in the inside but fully enclosed.

What we want to know is there a render setting that causes this or is it normal to jump so much because an object is open on the back?

[seandunderdale]

Is reflect on backside turned on? If the backside is open on the geo, and reflect on backside is on, that might be whats adding to the large jump in render time....thats is a BIG jump though.

[tourit_media]

This is the reflection setting. Doesn't appear to be on.



I also should mention that the render goes pretty fast except for the last 6 buckets in the scene sit there for the remainder of the 3 minutes of render time.

[Zdravko.Keremidchiev]

Would it be possible to send that scene for investigation? Please mention this thread in the form.

[tourit_media]

Unfortunately we use a NAS for all assets, so I'm not sure how helpful it would be for us to send the file because all the textures and proxies in the scene will be missing.

[Zdravko.Keremidchiev]

In this case, we will try to make a similar scene to reproduce the issue.

[Zdravko.Keremidchiev]

I was unable to reproduce the stuck buckets and long render time with a similar setup. It's probably something specific in the scene. Have you tested CUDA and CPU engines? Do they produce the same effect?