Distributed Render blur/distortion

[mikerogers74]

So when I render locally all is good. When I use DR I get distorted/blurry regions. These occur when the node synchronizes to the server. I am running same Max (2025.3) and Corona 12 Update 2 on both machines. I have tried the lock/unlock render view trick I read about in another post. Attached are samples of with & without blurriness.

Thanks

[Aram Avetisyan]

Hi,

This looks like a clear bug.
Please send the scene over so we can check.

You can as well do this through ticket: https://support.chaos.com/hc/en-us/requests/new

[mikerogers74]

Thanks Aram,

I have literally stripped the scene back to nothing.... a plane with a material with a png feeding displacement and a camera with environment lighting. And still the issue. Zip attached.

Some more things ... I have identical NVIDIA studio drivers on the two PCs, system unit setup the same. Not sure what else to double check.

Oddly, using a Noise instead of a Corona Bitmap to drive displacement does not cause the issue. When I add CInfo_NetworkRenderDebugging I get blurry results

I don't see how it could be a bug with such a simple scene?

[Avi]

I am unable to reproduce the issue on my end. How many passes did you render it?

[TomG]

Just observations to go into the bug searching

- Since it is the middle third of the image, looks like something to do with sections of the image rendered on one machine vs. another
- It looks less like blurriness and more like ghosting, it's as if three or four versions are overlaid each slightly offset
- Does changing the synch interval and/or max pixels to transfer at once make any difference? Either resolving it, or changing where it happens in the image? The end render is very large so there could be something to do with the network itself getting overwhelmed with data (what is your network speed btw?)

[Frood]

First thing I would test is to replace CoronaBitmap by standard bitmap :)


Good Luck

[mikerogers74]

Hi Tom,

- Since it is the middle third of the image, looks like something to do with sections of the image rendered on one machine vs. another

Yes, it is definitely when the render node completes a sync interval. On the render node I see something like 2025-05-15 07:33:29   Started EXR dump (46,424,108 bytes, filename: C:/Users/Mike Rogers/AppData/Local/CoronaRenderer/DrData/dump9835.exr)

Then a second later the render ghosts. See attached screenshots.

- It looks less like blurriness and more like ghosting, it's as if three or four versions are overlaid each slightly offset

100% correct

- Does changing the synch interval and/or max pixels to transfer at once make any difference? Either resolving it, or changing where it happens in the image? The end render is very large so there could be something to do with the network itself getting overwhelmed with data (what is your network speed btw?)

The network is 2 modern laptops (pro art 16 and legion 9i) direct connected and tested at 1 gigabit. Legion has ethernet port, pro art has 10gb usb-a ethernet dongle.

The ghosting comes across in bands depending on the number of pixels. Fewer pixels = more bands but after a while the entire image is ghosted.

Hi Frood,

Same issue occurs regardless of Corona Bitmap or std bitmap

Thanks,

Mike

[maru]

Are you using some kind of special setting, modifier, or a script for your camera? For example tilt/shift? Is there a chance that it is missing on one of the machines?

[mikerogers74]

No, just a vanilla corona camera

[Avi]

Continued in ticket #377965

[mikerogers74]

So while I am waiting to sort out a time for a live session with support I thought I would post a clue which might help jog a thought.

The previous ghosting images are with me using the image into the displacement channel of the material. I tried plugging into base color just to see if the shift happens there and it does not. What does happen is the section that was previously ghosted is darker as per attached images. Could this be something to do with some sort of color/gamma thing? The displacement would look like it has shifted because the bitmap is brighter/darker on different machines. I am using Max 2025 with the standard OCIO Default on both machines so not sure what else to look at...

[mikerogers74]

And one more post... the problem does not occur when I switch to Color Management to Gamma Workflow. Not sure if this might shed some light...

[maru]

I am pretty sure this is a bug in 3ds Max which makes textures render differently with the OCIO color management mode and command-line / network rendering. The easiest way to verify this would be checking the same scene in Max 2026. We are on it.

[mikerogers74]

Can confirm Max 2026 is fine in OCIO

[Avi]

Can you run Corona converter one time and see if the problem remains same?