Render starts fine then starts turning black?

Started by donnievegas, February 23, 2012, 12:31:01 AM

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donnievegas

Hi all, firstly I have to say how amazing it is to use terragen again after a few years off! Amazing stuff guys and gals!

Anyhow I have a nice scene that I have rendered a few times, it's water and clouds with no visible height field. Previous renders and small renders are fine. So earlier today I set off a large render at 4096 by 3072, it started doing the whole rendering dots thing, that lasted for 9 hours and once the whole render window was filled with the dots it then started again only this time it's rendering black sections. The render has been going for 13 hours now and it's about 70% black now.

Is this normal? Will my render be ok in the end? Or does it sound like its gone pear shaped?

Setting were normal other than the large size.

Any help or ideas would be great.

DonnieVegas

Oshyan

It sounds like it may be running into memory issues and aborting render tiles, leaving them black. Can you give some details about your system, how much physical RAM you have, your CPU, and what operating system you're running?

With a 9hr GI prepass, I would guess you either have a slow machine, or have very high GI/detail settings. That could be contributing to memory issues, especially at that fairly high resolution.

- Oshyan

donnievegas

Hi Oshyan,

I am using a 2010 27inch iMac, running osx and using intel 3.06 core 2 duo with 8 gigs of ddr3 ram

I have not changed any settings for the full render other than moving the detail slider to 1 and checking ray trace atmosphere

the G.I settings are all 2, 2 and 8

Any ideas

Oshyan

Hmm, it doesn't sound like that would necessarily be causing memory issues, although if the scene is particularly "heavy" (lots of objects, textures, etc.), and was already pushing memory use, then increasing the resolution might have put it over. What is the antialiasing setting? Can you share a lower resolution version of the render so we can see what's in the scene?

- Oshyan

donnievegas

The antiallasing was set to 3 and all i have in the scene is water and clouds?

jo

Hi,

If it was memory problems I think there would be messages in the Console about it. You can find the Console applicaton in Applications > Utilities. The messages would something along the lines of "Unknown error occurred in..." trRenderBucket or TraceRay or something like that. Those sorts of warnings should also be posted to the Errors and Warnings window though. If you look at the main window is the number next to the little yellow warning icon in the bottom right corner something other than 0?

Regards,

Jo

donnievegas

Hi Jo,

Thanks for your response, I think you are right because I tried the same render on my pc but at half the size and the same thing happened and I got the same error messages you mentioned. The thing is on my iMac that did not happen, it just kept going.

Anyhow is there any way to tell that something like this is going to happen prior to hitting render?

Please excuse if that's a stupid question! Just seems a bit of a gamble if you cant tell, or is there a formula for working this out beforehand. Also is it possible to say render a cropped version say 1/4 of the screen and then do this for each corner and then stitch them together lol?

Seems weird that all the setting were on default other then the quality, yet I ran out of memory with an 8 gig machine.

Still, am absolutely loving Terragen 2, its amazing! Just need to build me a new pc now!

donnievegas

Just to update, it seems that when the screen goes black in places DURING a render that all is actually fine. I just finished a 2 hour render and the same thing happened to about a quarter of the render screen, but as the render continued they were all eventually filled in with lovely hi res details!

Damn, I ended up cancelling my previous render after about 15 hours because I thought it was broken lol!

Thank you again for your replies.

DV

Oshyan

I think I understand what was happening, and it wasn't a memory issue, which is good. When TG2 renders, it starts with the GI pass and fills in with "dots" that represent light samples in the scene. When primary rendering happens, it "erases" the visible dots for areas it's rendering. For longer renders this effect would be more noticeable and would also depend on the render tile size (which is affected by AA, in this case a fairly low value, so the tiles were large and would affect a larger area).

So in any case, as you found, it's not an error and everything works out fine. Sorry about the confusion and having to cancel a long render!

- Oshyan

TheElectroKangaroo

#9
I've got a similar concern... After the GI dots have appeared, absolutely nothing happens for about an hour, then the whole scene gets drawn in one go (this is on the max 800x600 render size). Is this a gfx problem? I've got a 32mb laptop gfx chip, 1.12 Gb RAM and a 1.4 Ghz processor.

donnievegas

Hi there Kangaroo,

I am replying as this is in the thread I started, but I am sorry I cannot answer your question, though it does make me think about having a feature that tells you if the render is still running? In my case I stopped a 15 hour render that was in fact working fine in the background, but the screen was just black for ages (after GI dots where rendered). Since then I discovered it was all still working so its not a mistake I would make again.

Having said that I suppose I could have gone to Task Manager and seen that Terragen2 was using loads of CPU time, and then deducted that it was still working.

I am sure someone much more technical than I will answer your question very shortly.

DonnieVegas


TheElectroKangaroo

Yes, but you can't get to Task Manager because of the outrageous amount of CPU time T2 is eating.

donnievegas

That's true dude, but I have to say that you probably could do with a faster CPU and more RAM or you will be sitting around and waiting while your little laptop squeezes out those renders! I am sure it has served you well though, its just Terragen2 is a beast!

Best of luck

Don

Oshyan

Quote from: TheElectroKangaroo on February 28, 2012, 01:03:34 PM
I've got a similar concern... After the GI dots have appeared, absolutely nothing happens for about an hour, then the whole scene gets drawn in one go (this is on the max 800x600 render size). Is this a gfx problem? I've got a 32mb laptop gfx chip, 1.12 Gb RAM and a 1.4 Ghz processor.

I don't think it's a graphics problem, you just have a very slow system so it takes a lot longer to complete the GI pass and primary rendering. How does it behave when you turn off GI? Does it still get drawn "in one go"?

- Oshyan

TheElectroKangaroo

I dunno, I never tried disabling GI. I'll try it tonight.