Render freeze

Started by xsimekp1, October 15, 2018, 06:42:01 AM

Previous topic - Next topic

xsimekp1

Hi,

we hav got a problem with rendering, whenever we render to some larger resolution (we tried 20k) it freezes during a render. Sometimes after 30 minutes, sometimes after 4 hours. We need it really high res.
I do not have there any objects nor complex node system. I need it just for the sky (clouds + sun).

What could be the problem?

Pavel

ajcgi

I had a similar resolution thing to do recently.
It's a boring answer, but render it out in tiles, say 4 or more. Copy your scene with a different crop region and output path in each copy. Make sure you have an overlap on those crops and that your GI is considering the whole view, not just crops or you might get trouble. Then blend the whole thing together afterwards in Nuke or After Effects or whatever.

The problem seems to be a bottleneck at a certain resolution. I decided I don't care what causes it, I just need a workaround and this always works. ;)

N-drju

#2
Render freezes happen when a computer has too little RAM to process a scene. In that case (prooved on Win XP back in the days) a render will start and carry on for some time until it reaches a more demanding render bucket. Usually it may be a bucket containing objects or glass / reflective surfaces. If it is too much for a system to take on, Terragen will return an error and a bucket (along with the core that was scheduled to process it) will be irreversibly dropped out from the rendering. When another problematic bucket is about to be rendered it may, likewise, be dropped again.

If a scene is very complex and this situation goes on and repeats itself, you may suddenly find yourself in a situation when there are no more "free" CPU cores left to process an image. By then, you are left with the image being still technically rendered (timer still ticking) but having dysfunctional render buckets that prevent CPU cores from rendering any further.

Render freezes are very rare if you have anywhere close or above 8GB RAM. If you have that much RAM, I would suggest to repost in the "Terragen Support" section, because the root of the problem might be different.

You may also try what ajcgi, correctly, suggests and render your image in small "crop renders". Crop renders generally fair better in limited RAM environment. This technique may be burdensome however, as you can never really tell what size the cropped area should be for it to successfully bypass RAM limitations. You don't want to make forty crop renders to keep errors from occurring. But also, you don't want to render a crop and find out that, after all, it was still too large for your system to handle.
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

ajcgi

That's a fair presumption, that RAM would be a factor. The last time this happened here, it was on a render node with 64GB and started to freeze at around 40GB. So perhaps there's a point beyond which the RAM can't be addressed on a large render.

[edited to add last 4 words ;)]

SILENCER

Send it to Pixel Plow, they'll render it.

It's worth the money. I've done 16K spherical backgrounds there that would have occupied my machine here at the shop for a couple of days.


https://www.pixelplow.net/pricing/


WAS

From what I gather from pricing, they're not too expensive. A 1080p still I believe if I'm remembering correctly could run a dollar something something that would render for 6-8hr for me.

Oshyan

I have a machine with 128GB of RAM and have routinely addressed 100+GB of it with Terragen. So it's not a Terragen limitation for memory addressing. But I would definitely check memory usage first in any such freezing scenario with high resolution rendering. Keep in mind that the higher the AA and detail, the more clouds and higher the voxel count, and the more render elements you have, the higher the memory use. So even if your scene *seems* simple, it may not be as far as rendering and memory use are concerned.

- Oshyan

N-drju

#7
Quote from: Oshyan on October 15, 2018, 05:45:59 PM
I have a machine with 128GB of RAM and have routinely addressed 100+GB of it with Terragen. So it's not a Terragen limitation for memory addressing.

I think we have a consensus that it's not Terragen's fault that memory is cut out of the rendering process. Maybe I mismatched a word or two. :) Of course, I mean a system doing strange things to "preserve vital functions". I remember my first goes on XP with TG 2. It was horrible...
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

ajcgi

Quote from: SILENCER on October 15, 2018, 02:56:18 PM
Send it to Pixel Plow, they'll render it.

It's worth the money. I've done 16K spherical backgrounds there that would have occupied my machine here at the shop for a couple of days.


https://www.pixelplow.net/pricing/

This presumes their machines won't freeze too. ;)

WAS

#9
What operating system are you on anyway? It's highly unlikely Windows 10 would freeze when dealing with RAM/Memory. It should end the process, meaning TG would just crash to desktop, with maybe an exception error.

With only 8GB+Commit, in scenes with populations, I often have to experiment with what my system can handle. Usually it will get to about 20gb with about 5gb to spare of commit before TG will just crash to desktop. If I'm holding at 15-16GB of RAM+Commit, holding steady, I know things should be fine, anything happening would likely be due to something else, such as CPU usage with background tasks.

SILENCER

This presumes their machines won't freeze too. ;)


They're pros.
Render like a boss and save a headache.

N-drju

Quote from: SILENCER on October 17, 2018, 04:04:19 PM
Render like a boss and save a headache.

...not your money though. :D
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"