Optimized setting for high resolution

[PixelJockey]

Hi kids. 99.99% of the time the highest resolution I render to is 2048x1536. Very rarely am I asked to do something like 4096x3072 or higher and when I do these renderings the render time is astronomical. Generally I find render time is pretty close to a function of pixel area. If a 1024x768 images takes 15 minutes then a 2048x1536 images takes 1 hour, so in theory a 4096x3072 should take 4 hours. Instead it takes 12 hours.

I'm wondering if I'm fundamentally missing the boat when it comes to VRay settings for high resolution renderings. For a 2k image of an exterior architectural scene I can usually get away with IR map set to medium and Light Cache set to 1200. When I go to a higher rez image I find the renders usually crash with an unhandled exception during the LC calculation. So I turn off LC and use Brute Force for the secondary bounce. I don't get crashes but still have very long render times.

So should I forget using the presets for the Irradiance Mapng and adjust the settings manually or just accept half-day renders? I'm not looking for a magic bullet, I'd just like to know what other users experience are with high rez images so I can know if I need to rework the problem or just sit back and enjoy the render time. Any nudge in the right direction would be greatly appreciated. Thanks.

[jujubee]

Make sure you're working from saved irmap/lc files.

Your error is a memory error. Make sure:

1) Use instances whenever possible.
2) Make sure everything is ungrouped before rendering (eats up a ton of memory in Max.)
if you're fine without a preview, turn off frame buffers and save to image.
3) Turn up your memory limit.
4) Use the memeory switch for x32.
5) Optional - split your rendering (or render region) than render the other half.
6) Switch to x64 bit - probably the best and easiest option available.

[PixelJockey]

1) Use instances whenever possible. - Yep, all the time.
2) Make sure everything is ungrouped before rendering (eats up a ton of memory in Max.) - Yep, I hate they way Max handles groups.
if you're fine without a preview, turn off frame buffers and save to image. Yep - I do that too.
3) Turn up your memory limit. - Hmmmm... I'm not sure what you mean there?
4) Use the memeory switch for x32. - I render to a 64 bit render note with 8GB RAM.
5) Optional - split your rendering (or render region) than render the other half. - Ahh yes. I alway forget about that.
6) Switch to x64 bit - probably the best and easiest option available. - Yep and done.


So I've done most of that, but I think splitting the image just might do the trick for me. I'll give that a shot on my next big render tonight. Thanks for info. I feel better already.

[jujubee]

Memory - dynamic or raise static memory limit.

Also,

1) use proxies
2) DO NOT USE Standard Mats!!!
3) DO NOT USE Raytrace Mats
4) Clamp output
5) Make sun invisible if necessary
6) If possible, do not use AA at high resolutions
7) IES lights add a lot of time.
Turn down light subs for lights hardly seen.

Umm what else.
IRMap Medium settings is often overkill.

I'd almost have to say that we would need to see your settings.

I just rendered a still using DR - about 20 buckets at 3200x2400. Lots of lights and glossies - took about 2-3 hours to process. That seems within normal range for me.

[PixelJockey]

Jujubee

1) check - every chance I get
2) check - I always use VRay mats
3) check - Raytrace! What kind of amature do you think I am!
4) Hmmm... okay maybe I am an amature. I rarely clamp output.
5) Hmmm... okay and that has an affect on render time?
6) Ah yes.. I do use pretty aggresive AA.
7) check - almost never use IES
I have quite a few VRay lights. They are set to store with IR map. And one VRay sunlight.

When I get a chance I'll post settings. But for now I'll try tinkering with some of your suggestions.

Thanks again.

[MoonDoggie]

Don't forget IMAP settings are dependant on resolution, the ad-hoc rule has been you can lower the min/max by one everytime you double the resolution.

Lightcache is the same way, but needs to be increased for higher resolutions for the same effect.

AA is not a reason you crashed, but it is a reason your renders are taking so long, do a test with AA set to fixed at 1, compare render times

-Colin

[tehamnes]

You could precalculate the Irrmap and LC at half the resolution of the final image but with higher settings - that would save some time overall too. The difference in quality should be minimal.

[glyph]

what tehammes suggests is the exact same result as upping the min and max ir values - (ie as moon doggie suggests) - that's the least trouble unless you might want to reuse the ir map later - I regularly do (simple) scenes at 8-10k across no problem

[MikeHampton]

Yea.. I've had the same problem with trying to predict render times. I will use very low settings, turn off displacement, set global subdivision multiplier to .01, use light cache for for both primary and secondary bounces, etc. so that I have a very fast preview render time, like maybe 30 seconds. So I figure if I am rendering a scene with those setting at 600x300 in less than a minute, my "scanline thinking brain" figures that turning all the setting back to "normal" and rendering a 1280x720 image the render time should be no worse than 10 minutes, but I may end up with a 9 hour render time!!! :O


As you increase settings and resolution the render times definatly seem to increase exponentially, NOT linearly. So as you are working you occassionally need to do a high res/normal settings rendering just to get a feel for how the render times are comming along so you are not suprised at the end as your deadline approaches.


But I have one thing to add and one question to ask.

I have more or less shyed away from using Vray lights. I use the Vray sun, but other than that I use standard max lights (non IES) wherever I can. The reason being is that Vray lights are all soft shadows. Soft shadows are awsome but if you don't HAVE to have them.. don't use them. I've done tests where soft shadows alone increased my rendertime by at least a factor of 2-4! So unless you have a specific reason to, I would avoid using Vray lights.


Now my question: How does using groups negativly affect memory in Max? I explictly group everything in my scene. I can't stand to go to the selection box and have 30,000 items listed in there. I just want to see about 10 or so groups and then nested groups within those. That way with just about 3 mouse clicks (using isolate selection) I can isolate down to a single chair leg without ever having to look at names of objects in a pick list. So am I killing my memory by doing this?????? :O

[m_hinks]

You could precalculate the Irrmap and LC at half the resolution of the final image but with higher settings - that would save some time overall too. The difference in quality should be minimal.

You might as well just reduce your IR min/max by 1, thats the same as rendering to half res.

So if your image is looking good at -3, -1, rendering to half res is the same quality as rendering with -4, -2 at full res.

Ill get corrected if im wrong but I've seen this a lot on the forums, pretty sure its right!

[jujubee]

How does using groups negativly affect memory in Max? I explictly group everything in my scene. I can't stand to go to the selection box and have 30,000 items listed in there. I just want to see about 10 or so groups and then nested groups within those.

I completely agree and I don't know why. It's been that was for Max 8 and 9 and across 64-bit. This has nothing to do with Vray.

When I wasn't on 64, I had trouble rendering very intense scenes. Ungrouping items was one way to manage memory better. Just be sure to work with layers.

As for 64bit, you'll still notice a viewport slowdown on an intense scene until you ungroup everything. I usually ungroup everything as a last step measure prior to final rendering - just save another version in case.

[werticus]

nesting groups is the biggest no no of all - no one knows why but your basically killing your render times / memory use. This was brought up on the forums a long time ago however. (like 2yrs or more)


use selection sets instead.

[MikeHampton]

Ok... of course I had to see this for myself.. and I'm not getting the same results.


This is only ONE test, but I took a recent file I was working on. Rather complex scene about 2 million polys. LOTS of glass, transparent and frosted. Plus cars in the scene. So LOTS of reflection and refraction going on (including blurry reflection/refractions). Also had some displacement for some topiary trees.


I opened the file and exploded the entire scene so there is NOTHING grouped. I saved the file and rebooted the computer. Upon a fresh reboot with no other applications running at 1700x1100, the render time was 41m 29s for the scene with NO groups.

I again shut down and restarted the computer. Reloaded the original scene which EVERYTHING is grouped (I probably have groups nested about 4 levels deep). The entire scene at the top level is probably only about 6-8 groups. I rendered with all the same settings at 1700x1100 and had a render time of 40m 53s.

So the render time difference was basically negligable with the GROUPED file actually being just a tiny bit faster.

Of course this is just ONE test... but maybe they have fixed any memory problems with groups in Max 9???

On one hand I would gladly do anything to significantly reduce render times, but on the other hand I am rather relieved there seems to be no differnce because I use groups so extensively. The only problem I have ever had with groups is that for some reason if you have a group that has tens of thousands of objects in it (even if each object is just one polygon).. there is a notciable slowdown when you try to select that group, where if all those objects where attached into one object there isn't.

My next test will be to try to find a scene that I CAN'T render due to running out of memory and explode all the groups and see if I can at least get it to work.

[siliconbauhaus]

interesting about the groups thing as I group the bejebus out of everything (much to juju's dismay)

[RErender]

I always thought the group thing to be sort of a myth, maybe in some situations they could have an effect but I have not seen it. They can be a pain when your trying to recurse the objects inside for this and that but not too bad to work around. They sure are handy though.