3ds Max memory usage and render time

[vi3x]

Well, this is my first post here, so... hi everybody!

 

I am working on a relatively simple scene on 3ds MAX 2011 64-bit on a 64-bit system. The scene has about 100k polys, and the render settings are:

 

Size: 1920x1080;

AA: min 4, max 64;

FG preset: medium;

Reflection bounces: 4;

Refraction bounces: 6;

FG bounces: 4;

Glossy reflections: x2;

Glossy refractions: x1;

Soft shadows: x1;

MR Depth of field;

No caustics / GI.

 

Now, I started the rendering today at noon and ten hours later it hadn't finished yet. It seems like a HUGE render time to me, am I doing something wrong?

 

Then again I don't get MAX memory management. I've read on the Internet that MAX only gets the ram it needs, not a bit more. That's fine by me. What I don't get is why on a system with 4GB it gets only 800MB from the physical memory and 1094MB from the virtual memory. I'm not saying it should use all of my 4GB, but if it needs 1.8GB for my scene, why not using the available ram?

 

I'm running 3ds MAX 2011 64-bit with Win 7 64-bit on an Intel Quad Core i7-720qm 1.60GHz with 4GB ram.

[kris McIsaac]

The 3 basics for render time are lighting, materials and render settings. As you have provided the third one and it does not seem too extreme except maybe depth of field you may want to look at the other two. Lighting: What light sources are you using is it internal or external, daylight, Portals, artificial etc. how many lights and what sampling do they have? Materials: are they reflective? how many glossy samples? any translucent?

 

I usually do some tests using a matte white override applied to everything (except glazing) i will start with a sun and sky then start adding artificial lights. I will also start with lower render settings say 800x600, AA - 1/4, 1, FG low, FG bounces 1. Once I get the lighting working ok I start to apply the materials then do more low quality tests to check colour bleed and reflections then will start to up the quality. I generally wont go above AA 4, 16 and tend to keep the FG bounces at 1.

 

How far through was it after 10 hours?

 

I am guessing this is a laptop? That processor is not a super powerful one but should work ok. I would think it is the scene that is causing the long render times. Can you share your scene or provide more details about it?

[vi3x]

Hi kris, thank you for the response!

 

Well, I'm a bit ashamed to admit it, but I *kinda* noticed this was an architecture related forum only after I registered (which is not bad, since I'm planning to do architectural scenes, sooner or later...). But the current scene is about a metal watch.

 

The scene setup is a classic industrial design one: subject laying on a grey drape, like in a photo studio, two lights on the sides with no shadows, one from above with shadows (raytrace). The lights are all rectangular photometric (32 samples, uniform diffuse). The materials, given the subject, are full of metallic and shiny reflections but since it's mostly all chrome there are no glossy samples (only the plastic parts have some, but they shouldn't be more than 16 or 32, can't recall right now).

 

While it was rendering, I made the horrible mistake to minimize 3ds, which means I couldn't be able to maximize it before the render was done. I just figured that 10 hours were an unacceptable render time, therefore I thought it may be stuck (or that something was wrong anyway) and killed the app without being able to see how far it went with the process.

 

Today I tried another render without the two side lights, dropping the AA to 4+16 and without the depth of field. I went away and 1 hour later it was done. Normally I would use a pipeline similar to yours for my renders, and the previous render was fine. I'm thinking the DOF is the main culprit here, but I really need it for this job.

 

As I'm writing I launched another render, since I found out I put an exaggerate turbosmooth render value that didn't show up in viewport. Maybe that's it, I'll let you know how it turns out.

 

By the way, do you have any idea on the physical / virtual memory usage? I was considering to expand my ram to 6-8 gigs (it's a laptop, btw, I'm not a pro - yet! - so it's doing good for what I need), but since the software isn't using more than 1GB of physical memory it sounds like a waste...

[steyin]

10+ hours for a render of that watch is far too long. You can also probably reduce your sampling to min:1/max:16,a long with FG bounces to 2 or 3 to save some more time. You should never really need more than that, especially with such a simplistic industrial design.

[kris McIsaac]

Can you fake the DOF in Pshop? I have only used DOF a couple of times as most of my rendering is architectural exterior but with MR it renders in passes so it will depend on how many passes it needs. If your render without takes an hour and you have 12 passes...12 hours. Did you save the FG map? it may have been recreating that for each pass.

 

I have found that using the switch to or maxamise options in task manager will usually get Max back in Win 7. With memory a scene of this size should not be a problem with 4gb unless you wanted a billboard sized output but more is usually better. I tend to keep working while my renders are going and will go over 7gb often.

 

P.S. it looks pretty good so far.

[vi3x]

Actually I looked on the Internet for a lens blur in Photoshop, and I found it waaay easier (and without losing quality) to render a separate z-depth image from the scene and to import it in Photoshop as a depth map for the lens blur. I'm posting here the result, seems fine by me.

 

I'm not sure how many separate passes it needs. If I recall right you can choose how many passes it needs with the scanline DOF, but with the MR one I couldn't find such an option. I will probably lower the FG bounces but I'm not sure about the AA settings... how do you guys decide the sampling rate for your renders?

[kris McIsaac]

a few things that help me decide will be: The size of the final render, intended use of the final image, amount of post work required, time allocated for completion and past experience.

 

If the final render is just going to be printed in house or used in a digital presentation the samples can be a bit lower. If I am using an alpha to cut out the background or need to Photoshop a lot of details I will go higher. If I have 30 minutes until a deadline....lower! Also if the final image is big then the samples don't have to be as high to still get smooth edges. For detailed renders like yours then 4/64 is possibly what you need but for a basic architectural exterior 4/16 is usually fine

[vi3x]

Thank you, kris, you have been really helpful!