Render Settings Assistance

[ivanjay]

Hi all,

 

We just built our first render farm with a single high powered machine (48 cores to it) and I connected another Boxx workstation we have. However, my rendering is taking an insane amount of time.... I started yesterday morning and 24 hours later it is only 10% done (45 out of 450 tiles) via Thinkbox Deadline.

 

I am thinking that

 

1. Maybe the number of tiles is creating way too much overhead so reducing that will help a lot.

2. I am using a lot of glossy and reflective materials, but maybe my settings are way too high so the rendering time is up there.

3. The resolution is high because this is formatted for 11 x 17 300 dpi printed in a design book handed to people. I cheated the resolution down to 250 but not much more room there.

 

Ideas on what I should be looking at here to resolve? I did post another day about mastering mental ray settings and this is not a quick way around that. I am purchasing books suggested and reading up but unfortunately on this project I am against a deadline and need to get this rendering processed!

 

Thanks!

[blank...]

It will be very hard to say what's wrong, scene is not just render settings but materials and lighting too. The only two things i can see from this:

- lights intersecting geometry can sometimes cause problems

- those glossy multipliers at 3, are they really necessary?

[ivanjay]

It will be very hard to say what's wrong, scene is not just render settings but materials and lighting too. The only two things i can see from this:

- lights intersecting geometry can sometimes cause problems

- those glossy multipliers at 3, are they really necessary?

 

Dario,

 

I have been having issues with noise in my materials hence the reason I pumped up the glossy multipliers. What I found was that with unified sampling I am getting insanely long render times with not good results. i am sure this is due to me not knowing how it works now that it is new in max 2014. So I went back to the classic and set my sampling at 1 / 16 for min / max. I was still getting artifacts but much better render time so I now am at glossy multiplier of 2 with the same settings.

 

But, I do want to learn how to do unified as from what I am reading it is far superior.

[blank...]

I have been having issues with noise in my materials hence the reason I pumped up the glossy multipliers.

 

Try moving the lights out of geometry. I had that exact issue once, lights were intersecting with geometry and some materials had huge problems with glossiness and fireflies. After i moved the lights everything cleared up.

 

What I found was that with unified sampling I am getting insanely long render times with not good results.

Probably because the scene is not set up for unified (like we talked in other thread).

[ivanjay]

Dario, I appreciate all of the help thus far! I think I may have this Unified thing better under control. It does seem easier. This is the first tile out of 100 (it is the ceiling with a paint on it)

 

As you can see this is much better but still a bit of noise from what I can tell. This trip took 22 minutes so not great but not terrible (it is 11 x 17 image at 200 dpi)

 

Would you turn the quality setting 1 higher or adjust the max setting? I am currently at 1 / 300 on the min / max and 2 on the quality slider.

 

Or would you leave this as is and have it acceptable? I might be overthinking it just looking at a tiny small section of the tile zoomed in.

[blank...]

Dario, I appreciate all of the help thus far!

 

No problem, i to am still learning myself

 

This trip took 22 minutes so not great but not terrible

This still sound like a lot of time for that one tiny tile, how is your lighting set up?

 

Would you turn the quality setting 1 higher or adjust the max setting? I am currently at 1 / 300 on the min / max and 2 on the quality slider.

There really is no right answer but - test it. 1/300 should be enough, you can go up to 3 or 4 with quality.

But you can also try going down with max, and increasing glossy value to 2 or 4 just on problematic materials. That way materials that are not problematic aren't getting unnecessary sampling, and problematic ones are getting enough, so this could be faster (although oversampling shouldn't be a problem with unified).

 

Or would you leave this as is and have it acceptable?

Again, no right or wrong, its' up to you, or your client

[ivanjay]

haha fair answers. I need to let it render overnight to the full image I think and see how it looks.

 

Not sure if this is going to answer your lighting question in full but I have an HDRI image with a skylight (I did not see any sampling options anywhere there), and these are all photometric lights in the ceiling and the light cove.

 

I am assuming the rendering time per tile is that high because of the resolution... It is 340 x 220 per tile (10 x 10 grid to make up the full resolution image) and photon map and final gather map is already made and stored so I am just loading from that.

 

If you have any ideas on where to hunt to get that rendering time down a bit great, but if not I will let it go....

 

my renderbox is pretty substantial. 48 logical cores (24 and hyperthreading) Brand new from Boxx

[ivanjay]

Correction on the time, first tile took 9 minutes and the second took 12 minutes so averaging somewhere in that range.

[blank...]

Not sure if this is going to answer your lighting question in full but I have an HDRI image with a skylight (I did not see any sampling options anywhere there), and these are all photometric lights in the ceiling and the light cove.

 

For interior, definitely try the "old" mr Sun/mr Sky/light portals way. Hit F10 and change to "skylight illumination from FG". As far as i know mr native IBL is not designed with interior renderings in mind. Yes it will render, but render times will be much higher and quality of render will be the same (or worse).

 

Photometric lights - turn on far attenuation (set appropriate values); set "max quadtree depth" to 9 ("ray traced shadow param" rollout, renders faster and uses more memory, but i assume that is not a problem).

Edited December 26, 2013 by blank...

[blank...]

Regarding interiors IBL

http://forums.cgarchitect.com/75158-help-needed-mental-ray-artifacts-2.html#post384756

[Matt McDonald]

Your ceiling looks like it has fireflies on it. Are you using true glossy reflections? Generally, you don't need to do that on materials with a glossiness below .4 or .5 unless it is a special circumstance. I typically use highlight + FG only on paint materials.

 

Can you post a screen grab of your indirect illumination tab?

 

How are you submitting jobs to your BOXX? Are you doing so via backburner or opening the file? On occasion I have had MR scenes which when submitted via BB take hours and when rendered locally they take minutes. This is a rare case but just to be sure, you can open task manager on your BOXX while it is rendering if all or most of the cores are being used (depending on the number of buckets), you are good to go. If task manager looks like nothing is happening there is the issue. Unfortunately at this time my only solution to that is to render by opening the file.

 

You could look into optimizing your bucket size based on resolution and core count. I think you can find something about that in the help file. I've never had any luck with it but I've never had a machine with 24 cores.

[ivanjay]

Matt,

 

I am using the built in mental ray wall paint material for the paint. So I just choose Eggshell for most paints and semi gloss where that is what I intend to use. That shader does not give me much in terms of settings to play with.

 

I am remote today so I cannot grab the screenshot of indirect illumination tab. But, what are you looking for specifically as I can prob answer off of memory?

 

I am running a trial of Deadline as I was having some issues with backburner. Job distribution seems to be without issue. Some tiles render in 15 minutes. Others take 1 1/2 hours depending on what is going on in the tile.

[Matt McDonald]

Those aren't the default Mental Ray materials. Those are the default Autodesk materials. You really want to use the Arch & Design Materials. The preset that you are using looks to raytrace all reflections which you don't want to do.

 

As for the indirect illumination tab, I'd like to see your Final Gather settings and your GI settings (if you are using GI).

 

Different buckets will always take different amounts of time based on the sampling in that bucket. I'd still check task manager to see that your CPUs are be maxed while rendering. It's a long shot but it takes two seconds to verify.

[ivanjay]

Matt, what is the issue with raytracing the reflections just out of curiosity? Not that it is hard to create my own paint material at all but I do love the ease of doing it through the Autodesk materials....

 

Final gather and GI were precalculated and saved.

 

Final gather was slid to medium and that was the only change to the default settings.

 

Photons I did pump up the number of photons and checked all objects cause gi but that is the only real change

[Matt McDonald]

Raytraced refelctions, particularly glossy ones are really expensive so you want to avoid them when you can. Metals, glass, flooring...you might need to raytrace reflections on those but not everything.

 

Your final gather settings are probably too high. I'd bet you can get away with something somewhere between draft and low quality.

 

I'm also suspect of your GI settings but it's been too long since I setup a scene with GI and I don't exactly remember what they all do. Someone will be along who can help you with that.

 

I'm also a little curious about your lights. As Dario pointed out, having them intersect or too close to geometry can have significant render time impact. I'm curious as to which light distribution type you are using. If you are using uniform spherical on any of those lights they need to be switched to uniform diffuse so that they are not casting shadow rays in all directions.

[ivanjay]

Matt,

 

I appreciate the feedback and am going to look into all of this. Right now I do have it queued up on my rendering farm and I am kind of in that situation of wondering if I am better off just letting it render compared to endlessly tweaking and searching for the issue.

 

But, if I can get into it and make these changes before it gets too far along I am going to.

 

As for Final Gather.... I do have it baked so I am not continuously running it. Would having it too high still have an impact on my render time since it is just loading the file? Is there a method to evaluate at what point final gather is acceptable. I never know how to test that stuff.

[ivanjay]

FYI most of my lights are photometric

[Matt McDonald]

Yes, even though it was pre-calculated high FG settings will still contribute to render time.

 

For tweaking FG you are trying to balance detail, accuracy, smoothness and smoke. High initial FG settings will give you lots of detail but the render might be inaccurate and/or smokey because there are not enough rays shot from each FG point or there is not enough interpolation of the FG points to smooth it out. Adding rays will improve accuracy and provide a more smooth resuly at the cost of render time. Increasing interpolation will smooth things out with little impact on render time but at the cost of accuracy.

 

Until you really get the hang of things, I would error on the side of fast rather than beautiful. Getting an opportunity to see the rendering multiple times and fix things you don't like is pretty valuable.

[ivanjay]

Thanks for that, really helpful!

 

Might seem like a dumb question but what would I specifically be looking for in my renderings making them need either more rays or interpolation. The explanation is helpful but would i see non smooth transitions from light to dark? Or issues similar to my sampling? Just trying to get an idea on what I am going to see specifically.

[blank...]

I am using the built in mental ray wall paint material for the paint. So I just choose Eggshell...

 

Ouch, those materials are render killers. If you want fast renders don't use them. With MR only acceptable material is A&D (and Car paint and SSS in situations that require them).

 

 

Right now I do have it queued up on my rendering farm and I am kind of in that situation of wondering if I am better off just letting it render compared to endlessly tweaking and searching for the issue

If you're on a deadline, probably better to just let it render. But you will have to invest some more time to learn MR.

 

FYI most of my lights are photometric

That's fine, but like Matt said, check if they are uniform diffuse.

[Matt McDonald]

If you are seeing smokiness in your render (and you'll know it when you see it) you can address that smokiness with either more rays or more interpolation. More interpolation is faster but if you turn it up too high round objects will begin to look flat and corners won't have clearly defined edges. This is because too many FG points are being averaged (interpolated).

 

You can also turn on the FG diagnostic mode and it will give you an idea of what changes to the initial FG density do. You are sort of looking for a diagnostic which shows lots of green dots in corners and on complex objects. Personally, I don't get much help from that tool because I get obsessive about the dots..."there can always be more dots".

 

And for all of this stuff just throw a light gray, matte material over everything so it will render faster.

[ivanjay]

That is cruel that they put them in there and they are inefficient lol I may need to look at that as I use them a lot.

[ivanjay]

Alright guys... First off THANKS SO MUCH FOR ALL OF YOUR HELP

 

I only got 10 frames in before I had my render node on something else so I decided to try to fix and resend. Here is what I did:

 

Final gather was reported too high but since I already baked it I did not screw with those settings.

Check lights and they were uniform spherical. I made them uniform diffuse

I switched all materials out of Autodesk materials and into Arch Design material

Switched from IBL to Final Gather

Still using my HDRI as my exterior. I didnt want to switch and throw all lighting off balance

Used highlight + Fg and Interpolate where it seams appropriate.

 

Submitting to my render node now. 10 x 10 tile distribution so 100 tiles for it all set at 11 x 17 at 200 DPI

[blank...]

Switched from IBL to Final Gather

Still using my HDRI as my exterior.

 

Now you actually made it worse

 

Also, once you change something on ligting, old FG and GI "baked" files are no longer valid. Sure, you can use them but you are not getting the correct sollution.

Edited December 27, 2013 by blank...

[ivanjay]

How is that worse? IBL is for HDRI and the other for sun?

 

I think I will put in the mr sun as suggested and forego the HDRI and keep IBL off assuming all agree that is the better route.... With that being said... I want to put a gray material across everything and take a look but if I put in the override slot wont that remove my windows as well and thus eliminate a lot of the light coming in?