Scene Size Causing Slow mental ray Render Times?

# 1 15-05-2004 , 03:54 AM

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Scene Size Causing Slow mental ray Render Times?

I've asked a lot of mental ray questions over the past few months but as of late, I'm wondering if I have a serious rendering problem that can only be remedied by starting all over modelling my scene to help rendering times.

The scene I've built is NURBS heavy and I guess one solution I have would be to convert all of my NURBS models to polygons, then reduce those if they're too big. I really don't want to have to remodel the scene because I had a hard enough time as it was building this sucker. So, does scene size affect render times at all? Do NURBS models also affect render times? Any help would be appreciated immensely! user added image

Thanks!

Russell

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# 2 15-05-2004 , 01:34 PM

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Yes and Yes. user added image

If you have alot of fillets/trims with high tessellations, it will slow the render down immensely. Likewise, if you have a heavy scene with loads of mesh, the renderer has to calculate all that. Usually with large scenes, you render out various pieces at a time, then just comp it all together in a compositing app.

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# 3 16-05-2004 , 02:04 AM

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Terrific! Okay, now that this has been established... user added image

Is there a simple solution to this dilema? What is the best way to shrink this puppy down? Is there a way? I spent forever building the room and I'd hate to have to start over on it. If anyone knows, could you please tell me? You can even e-mail me the results off-forum if you'd like. And if you don't mind, could you explain it in color crayon for me. I'm still learning the ropes here. user added image

Thank you so much. And Nitro, thank you. BTW, is it difficult to set up rendering out several scenes then comping them later. Do you use After Effects to comp them together?

Russell

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# 4 16-05-2004 , 01:44 PM

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Read up in the manual on using render layers. Or if you want a visual guide, you can take a look at Rage's Introduction to Compositing tutorial here.

If you're comping several scenes instead of layers, just make sure you have something that represents the same scale (like say a cylinder representing a human) in each one so proportions are correct in the end. It's easier to just use layers and turn off what you don't need to see while modeling, then render things out in layers.

Compositing app is just a matter of personal preference whether it's AE, Digital Fusion, Shake, or Combustion.

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# 5 17-05-2004 , 03:30 PM

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I hope this doesn't come off as rude or pushy but there really is no way to shrink the file size down? I don't currently own any of those compositing apps and I'm still having enough trouble learning Maya so learning to render in passes and comping them may not be the best solution for me right now. I'm tempted to just eat it in render times and just learn patience. I've started to look into converting all of my NURBS objects to polys in the hopes that'd help. I've also deleted temp files in my folder to try and reduce clutter. Any other possible suggestions? Thanks for your time and help, Nitro. user added image

Appreciated as always. user added image

Russell

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# 6 17-05-2004 , 03:39 PM

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Mesh is mesh. It all gets converted to poly when rendered out. Using render layers is just the de facto way it's done for large scenes. If you can't do that, the only thing I can suggest is go into render globals and make sure you're using a small low quality render until you get the render view to be exactly the way you want. Then, up it to high quality and be patient. The only other way is really to rebuild your surfaces so that they're less dense.

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# 7 28-05-2004 , 11:56 PM

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Okay, here's a variant on that question... can file types, i.e. jpg, tif, gif, and God forbid, bmp, files impede render times as well? I know with BMP files, you're poop out of luck as they're sizes can be astronomical!

Russell

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# 8 29-05-2004 , 12:17 AM

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I would imagine that "if" the file type makes it faster or slower, then bmp would be the fastest one, because the other ones are compressed, which means that for bmp the image is created period, but for say jpg the image is first created and then is compressed, obviously adding the time it takes to compress ontop of the time it takes to create the image. But I don't know....

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# 9 29-05-2004 , 12:20 AM

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Hmmmm...

...fascinating... LOL! I need to give this some thought. Plus, I need to move away from my window and computer... a nice little t'storm is on its way and there'a tornado warning in a nearby county. Eek! user added image

Thanks , Mr. Phantom for your help. user added image

Russell

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# 10 29-05-2004 , 02:08 PM

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changing the file type wont really affect your rendertime much, the difference is neglible. However dont render as BMPs as they suck major ass and are huge files. Render as tiffs or tgas nothing else. Jpgs etc are fine for web but not good enough for this type of work (lossy comrpession etc).

If you are using mental ray I wouldn't worry about your scene size I would be more worried about your mental ray settings. there are many settings that can cause your render to take a long time. The min and max radius settings for one. I would look into optimising your render rather than shrinking the scene size. It will be less work in the long run. Mental ray is designed to handle large scenes etc so I wouldn't think your over stretching it. Post a wire of your scene and lets take a look at it.

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# 11 29-05-2004 , 05:16 PM

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Here's my wireframe. What else did you need? Did you need a picture of my MR settings at all? Thanks, Alan, for your help. user added image

Russell

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# 12 29-05-2004 , 05:17 PM

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Wireframe...

...here it is for real this time. user added image

Russell

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Russell Bolding
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# 13 29-05-2004 , 05:19 PM

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Actually, come to think of it, I really think my scene is poly heavy. Could that account for a little of my problem?

Russell

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# 14 29-05-2004 , 05:21 PM

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One more thing: Alan, you're a big MR guy, right? What setting do you use and what do you reccommend?

Russell

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# 15 31-05-2004 , 01:44 PM

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I'm not really that up on MR, im still learning, but i dont think that your scene is that poly heavy at all. what's your poly count at the moment?

Try setting it to preview final gather or something like that and look in the output window and see whta it's telling you. It may have some information that will tell you why it's running so slow.

Alan

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Currently working on: Your Highness

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