Corona render selected objects is terrible

[Husi]

Hi. I have been working n a project and I have to create multiple colour options for a few cabinet doors. So, the average time for my final render is about 3-4 hours. But when I render with viewport selection mode its much slower and estimated time jumps to crazy 15-20 hours. Any help on this would be appreciated.

[maru]

Hi, could you tell me if you are using the 3ds Max viewport selection mode (Render Setup > Common) or the Corona viewport selection mode (Render Setup > Scene)?
Could you also share this problematic scene with us (or a part of it)? You can use this uploader: https://corona-renderer.com/upload
After the upload is done, please remember to notify me which upload method you used (classic or Dropbox) and what was the file name.
Thanks!

[Ink Visual]

Just wanted to touch base on the above issue.
I had an impression this is not working ok in the past, although this week we had to re-render some elements in animated sequence, and indeed we encounter exactly the same issue.
The whole frame in HD resolution takes 20mins to render, if we use render selected option (from Render Setup -> Scene) and include list (i.e car wheels only), rendering time increases to 40mins minimum or more.
That is quite bizarre. Especially that our frame looks like the attached, two wheels, not very reflective.
We are using max 2022, latest corona 7 (hotfix1).
Can this be investigated before the release of Corona 8?

[romullus]

I think this is not the issue with incresed render time, but rather the issue with how noise level is being calculated. Corona ignores the fact that actual rendering is performed only on small portion of the VFB, which greatly skews noise calculation. If you are using noise level as render stop condition, you will get wrong estimate. The solution would be to switch to other stop condition, like number of passes, or time limit.

[Ink Visual]

Hi Romullus,
I think Corona surely is not taking into account the fact that only the small portion of image is being rendered, although we are not using noise level condition.
We use passes limit, 30 in that case, and it's not the estimated time that is wrong, but the actual rendering time.

Rendering region of the approximately similar size as the object we we're trying to re-render in "render selected" mode is just SO much faster (i.e whole image render time = 20min, region render time = 3mins, render selected mode = 40mins!).
Unfortunately rendering region does not work for animated sequence as our object (wheels) is obviously moving all over the place in every next frame.

[romullus]

Hmm, i didn't know that. Please report it as a bug then.

[GeorgeK]

Thanks for reporting this, we will investigate and report back if this is something that can be further improved.

[Ink Visual]

Thanks GeorgeK
I can later send over the file we used for this if it helps your investigation.
Cheers!

[GeorgeK]

Thanks GeorgeK
I can later send over the file we used for this if it helps your investigation.
Cheers!

Thank you I don't believe it's needed, I will update you as soon as we have some news on the matter.

Can you please clarify what progressive limits you are using?

(Report ID=CRMAX-1280)

[Ink Visual]

Hi,
I'm using passes limit only. All others set to 0.

[Ink Visual]

Hi, just bumping the thread up.
Was this fixed in latest Corona releases by any chance?
We're still on Corona 9 but are hoping to upgrade to 11 soon.

[maru]

Hi, yes, there were improvements to this in V10 and V11:

From V10 changelog:
Improved performance when rendering with masks
In cases where the user includes just a small object and the rest of the scene is not rendered we get up to 600% speedup. In non extreme cases it leads to around a 10% speedup

From V11 changelog:
Bucket rendering - improved decision when to revert to random pixel rendering based on render regions and rendering mask.

My suggestion is to update to Corona 11 Hotfix 2 - https://corona-renderer.com/download
Then test your case, and if you are still observing a slowdown, submit a new ticket at https://support.chaos.com/hc/en-us/requests/new