render CRASH!!

[thethirddimension]

Hi,

 

I am working on a model for a virtual store, which is situated on the high street. There are quite a few blocks imported in to the model for fixtures along the walls and midfloor, plus a counter etc... there are spot lights inside as well, large glass windows as well as the sun coming through the windows to help illuminate the in store environment. My question is, when I am rendering complex models that involove sun light quite often I will see the attached image while it is doing its final gather. If I reduce the lighting such as the number of spotlights it will sometimes get further on in the final gather process before it crashes and produces the attached image. However i have reached the point now where i can reduce the internal lighting no more (down to 3 spot lights) as reduce the number of blocks in the store and it is still doing it.... it is no not far off a hollow shell!!

 

It is of presentation quality (level 5) and 2500 x 1300 pixels, which i need as it has to be viewed on wide screen for presentations as well as printing purposes. And a point to not is if substitute the sun light for a few spot lights outside the buidling this problem doesn't occur, even if I ramp up the internal spot lights from 3 to 20!

 

If someone can help me determine what variable i need to change without sacrificing too much (or any) quality, or help me identify what is going wrong that would be great.

 

Thanks in advance

[Bill Tillman]

That's a very complex drawing and setup you're trying to render. The first thing we will ask you is what's under your hood. The CPU and memory available on your machine will have everything to do with this. If it were me, I'd try to lower the resolution first and see if the rendering could complete. If you still crash, then you're going to have to suspect that either your hardware is inadequate for this or you have a bad memory chip or something which is causing the crash. You also must realize that AutoCAD is not the real tool for something this complex and with all the lighting you're using. As much as I love AutoCAD it has it's weaknesses as well as it's strengths and this may be one time when it's just not up to the task. However, I would think the render would complete if your hardware is sound. Might take a long time but it should complete. Since the crash keeps repeating, I'm suspecting a memory leak or other hardware issue.

[thethirddimension]

the most frustrating thing is i've just invested in new hardware! It's got 8GB ram, Intel i7 processor and Quadro FX 3500 graphics card. You are right if I lower the resolution it will complete, and have just completed one at 2500 x 1200 however I had to remove more blocks from the model. The other thing is it's not like it's taking forever to do, the whole render only took 30 min! so it's cirtainly not dragging on for hours, it seems to be getting through it quite well and then crash!

 

I know what you are saying about AutoCAD not being the best tool for this particular task, however I think it can handle it ok, it's just when I introduce the sun it seems to not like something.

 

Is there a variable that can be changed which has a massive difference to the processing power required when using the sun, however sacrifices little quality?

[bora111bora]

good thing to do, before rendering high quality images is to restart your computer, and empty memory.

[thethirddimension]

empty the memory, how do I do that? and talking of memory, If I open up the Rendering properties pannel, right at the bottom it has a 'processing' section. My memory limit is set to 1048, can you shed any light on what this means? If i cranked it up what would this actually do?

 

Your help is appreciated thanks

[thethirddimension]

just had a quick read on the subject of emptying the memory, is this just a matter of turning AuotCAD off and on again?

[bora111bora]

when you restart computer your ram memory will clear, that is that i thought.

[Bill Tillman]

Yes, rebooting your computer might clear up some memory. But most of the stay-resident stuff you're running will just load right back into memory, like anti-virus, and of course M$ as well as other vendors have lots of things which run at startup and use memory.

 

The more memory you have available the better but I doubt restarting your computer will help this situation.

 

I often notice during a render that the Rendering Window title will show (Not Responding) sometimes for a few seconds or longer. It eventually goes away and my the render continues. I have noticed that when I try to work on other things during the render that things really slow down. Most of the time I just let the computer alone while it does an intensive render. But sometimes I need it and just have to live with it. However, my machine so far, is not experiencing the crashes you describe. I do some pretty intense renderings sometimes which can take 20-30 minutes to complete on this i7 quad core with 12 GB or RAM. You just have to get used to rendering be a pain in the neck unless you have the dough to setup your own rendering farm.

[Marty Evans]

And remember that you need to run a 64bit OS to enjoy anything above 4gb. With XP 32 bit, you can access as much as 4gb using the /3gb switch. I fought this on another very large rendering project that I did. Another option is to render the model in pieces and put it back together in photoshop when complete. Not ideal, but a workaround.

[Bill Tillman]

I prefer to use the GIMP these days over Photoshop. Photoshop is just too darn expensive and the GIMP is free and with only a few exceptions you can do everything with it that you can with Photoshop. They even have a plug-in for it which makes the interface look and act just like Photoshop.