Region render preview different from final output

[CodyBrown]

Every now and then this issue happens again. i have a customer change a single material  piece so instead of running the whole thing again i put the region around the piece i changed and just render that and save some time. when it shows up in the network monitor i can click on it to see the preview and it shows me its running what i want, but 45 minutes later it did its own region and looks like the base bounding box when you first turn on region is what it rendered and not the region i made. going back to look at the preview it still shows the correct preview and if i delete the file i can't redownload it either from the monitor, almost like it knows its wrong and won't let me do it.

does anybody else run into this from time to time or know of a way to prevent it? the preview and final renders are attached below.

Thanks!
-Cody

[Niko Planke]

Hey Cody,

We have tried to identify the issue you mentioned.
Sadly we have been unable to reproduce it reliably enough to find the cause.

Do you have additional informations that might help us with reproducing the issue more reilably?
Do you for instance recall if and what rendersettings you adjusted right before submitting the job? There might be a specific order of changes that can trigger this.

If you want to identify the issue earlier on(before the entire rendering is done), the "preview" tab in the Network rendering Monitor should always reflect the actually rendered image(excluding image styles).
The Thumbnail in the properties tab on the otherhand  uses a snapshot of the realtimeview at the time of saving and might not expose the error depending on what causes the error.

I hope we can get to the bottom of this.

[CodyBrown]

Hey Niko,

thanks for that info, i always looked at the preview on the properties tab. that makes way more sense it shows a snapshot of the real time view and not the actual output after the error occurs after its sent to the network.

i can set it up to render the area i want but whenever this issue happens it always renders to what seems like the "default" bounding box when you first turn on the region before you adjust it to what you want.

it happens sporadically in every scene that i work on no matter file size, # of materials/models, etc. the only thing that i have found that kind of gives me a heads up this is about to happen is i turn on region, shows default bounding box, adjust to size and location of scene i want rendered, notice another change so turn region off to make another fix, turn it back on and it goes back to the default size of the final one i attached originally. i can readjust it again to size and location i want, turn it off and back on and it defaults again. when its doing this i've noticed if it goes back to default and i change it to what i want again and render, the preview in the network monitor will show what i set up in the screenshot (didn't know to check preview tab but will from now on), but it will render the default.

to avoid this if i need a change i'll make all my edits and turn on the region and set it up and render making it a point not to turn region off so as to give it the opportunity to go back to default if that makes sense. if i do need other edits and turn it off and back on and notice it defaults, I'll close out the scene and reopen it (which in itself is a time suck as the scenes range from fairly small to up to 10GB) but it happens across all my scenes.

no render settings changed before sending this particular one either. i have master files set up for post so i render all customer items in the exact same size and samples every time.

not sure if this extra information will help you squash this bug but knowing the preview tab should always reflect the real final output gives me a more accurate idea if its running way more than i need and if it'll save time just to stop it and render the correct area. thank you for taking the time to look into this though and get back with me, it is greatly appreciated!

Thanks!
-Cody

[Niko Planke]

Hey Cody,
Thanks a lot for providing the additional information it gave us just the right hint.
I have found at least one way to reproduce this now.

The issue appears to be triggered with specific aspect ratios (in my case 1600x1200) if the region is located directly along the bottom edge.
Be aware that this can also happen in Local rendering.

I will provide that information to the developers to get this adressed asap.

Thanks again for providing the information.