Render Times too long or just a Patience Problem?

[Helldoor]

Hi there.

As this is my first thread here, I should probably introduce myself a bit:

My Name is Teo. I have studied Architecture and decieded to concentrate on the Visualisation and Graphics area, after finishing my Masters. I settled a small project - Helldoor Visual Studio - my One-Man-Visualisation-Studio. The focus of my work lies on Architectural Visualisation. And that's where my question begins.

The Question
I recently visualized a small family house [pictures attached]. Although the Rhino File isn't any big - 222.0 MB, and the scene doesn't contain too many polygons, the render time estimated 13 Hours!

As for I'm not overly experienced with Rhino and VRay, I wanted to ask you folks, if these 13 Hours are normal, or am I doing something wrong (false material or Vray settings in general)?
Any tipps and tricks, according my workflow, settings, etc. are very, very welcome!


Thanks in advance!


Software:
Rhino 5.0 (64-bit)
VRay 1.5 (64-bit)
Windows 7 (64-bit)

Hardware:
Intel(R) Core(TM) i7-2670QM CPU @ 2.20GHz
RAM 16GB (2x 8GB SODIMM 1333MHz)
AMD Radeon HD 6700M Series
Intel(R) HD Graphics Family

[fooprobe]

it's really hard to diagnose from a distance. it *is* a large output size. but can you identify where the render seems to take the longest? does it hang on the light cache, IR Map, or final pass? or all of them? is your light cache and IR Map optimized? I prefer using adaptive DMC for image sampler, it's better with blur, but it's hard to say if that's going to help.

some other possibilities:
it looks like you're using displacement... but i don't see much effect in the render. try turning it off. at least you'll find if that's causing a problem, then you can work on optimizing it.

also just try overriding the materials in the global switches with a plain color. if the render speeds up dramatically, you know its a material causing the problem, then you just have to figure out which material.

try doing some troubleshooting and post again.

[Helldoor]

Hi emil,

thanks for the quick response.

I'll try to answer your questions:
The longest render phase is the final pass - approx. a half of the whole render time. I don't think, that my IR and light cache maps are optimised, as for I don't know how to optimise them. How do I do that?

I'm not really using much displacement - only for the roof texture. That can't be too much or can it?

I also have the feeling, that all the lights I used, incredibly mess up the render times. Could that be?

And one more question - how long do you estimate the render duration of this scene (if everything would be normal and correct)?


Thanks. Greetz.
Teo. Helldoor.

[fooprobe]

LC - reduce subdivision until you see black pixels at end of LC pass (or increase until you don't). In future use 0.7 multiplier for LC in indirect illumination

ir map - min = -3, max = 0, hsph = 50, samples = 20. Increase hsph and samples until blotches go away

if your metal roof has blurry reflection (glossiness less than 1) then switch image sampler to adap DMC. Min = 1, try Max = 8 and increase towards 16 to reduce graininess

good luck

[fooprobe]

You don't have an especially fast CPU. You could easily be in the 4-6 hour range or higher with a large scale render.

and just how many lights do you have?

[Micha]

I think the render times are much to high for an exterior. At the forum tutorial section should be an old starter kit thread where you can find some ideas for a basic workflow.

My hints:

* try to stick at max refl/refr depth 1, try to use glass without refraction for windows
* disable filter maps for GI - never missed here
* I use image sampler adpat DMC (1/6) all days, for it me it works more stable than adapt subd, try a higher noise threshold like 0.015 or 0.02
* secondary GI multiplier 0.8 could give lower times and more real looking light transportation
* LC subdivs looks good, most this pass should be done within a short time like one minute
* LC ... use light cache forglossy rays should bring down the render times a lot
* are the interior lights the speed killer? test it, maybe there is something wrong

Your IM settings are not shown at your screenshot. I use min/max -1 most, only if I miss small details I would use 0, but the GI AO is good enough to enhance details most

You are working with the linear workflow, anything at gamma 1 and final color correction in postwork?

[mcvltd]

Render times are definitely too high.

My recommendations would be -

1- Use adaptive dmc for your image sampler. 1/6 for test renders and then 1/12 for final renders.
2- For the dmc sampler use a noise threshold of 0.005 for test renders and 0.003 for finals (if using brute force gi then 0.003 and 0.001).
3- For IM settings I'd go with -1/-3 and use the detail enhancement feature.
4- Be careful of using LC for glossy rays - quality will be reduced if your light cache isn't detailed enough (higher subdivs).
5- Be very careful with displacement - an edge length of 4 is ok for small sized renders (1000 pixels wide) but you'll have to increase this as your render size increases. Keep in mind that the higher this value goes the less detail you'll get in your displacement. You may not need to go higher than 15 to 20 for this value. A good way to check if displacement is an issue is to have your task manager open while rendering - if your cpu usage is jumping up and down constantly while the render is in progress then you'll need to increase the edge length until cpu usage is constantly high.

It also looks like you've altered the setting for the raycaster parameters - I'd leave these as default for the moment.

Are your trees part of your render too? If so, then look at the transparency of your leaves - I remember a lot of people in the max forum had problems with slow clip-mapped leaf textures. Also having translucency on the leaves will add to render times.

Can you tell us what you are using for your environment textures?

Also, what settings you've got for your lights.

Rob.

[Helldoor]

Thanks.

Hey there folks,


huge thanks for all your answers so far.

@ fooprobe : .I have 17 lights. Their settings and the settings for the "Sun" I use, can be seen in the pictures attached.
.And as for the render options, you suggested - I'll test them and give you a shout about it later.

@ Micha : .I'lt test the settings, you recommended and tell you later, how they worked.
.And - sorry for the dumb question, but what are the "IM Settings". I couldn't get the "GI AO" either.
edit: dammit. IM = Irradiance Map.... I attached my Irradiance Settingsa also as a pic.

@ Rob : .Same as by the two above - I'll test the settings and let you know, what worked best. (sorry, it ain't any kind of competition or something like that...)
.The light settings can be seen in the pictures attached.
.The trees are not rendered - I added them in the post-production process.
.The Environment - ist's a HDRI Map, I use for the GI(1.25) and the Background(1.50). The settings - Filter-Blur 2.0 / Gamma 1.5 / UVW GenEnvironment / Spherical Mapping


Thanks, once again, dudes. I'm really happy over all the tipps n tricks I get to hear from you.

Greetz.
Teo | Helldoor

[fooprobe]

17 is way too many lights inside. One per room should be plenty.

[Helldoor]

17 is way too many lights inside. One per room should be plenty.

But I have some Paper Lamps (such as the IKEA ones), which have 3 "light bulbs" (=3x Lights). Should I have taken one rectangular, double-sided light instead?

And to summerize the question - are there any light types, that are easier and better to be rendered, than other?And what are the pros and cons?


Greetz
Teo | Helldoor

[Micha]

No render time is added if you use emitter materials instead lights. If you render exteriors only, maybe you can stick at emitters for the interios. If you need lights, be careful with the shadow subdivs, it increase the render time

GI AO - mean ambient occlusion at the GI options (adds a light shadow effect around details). Try -1 instead 0 for max rate (you will lost very tin details, but I would use 0 only if I miss details, you save a lot of render time).
I tested multipass in the past, but don't found an advantage. So, I would disable it.

[fooprobe]

i agree with Micha - you can use emissive materials on an object inside your lamps to make them glow instead of point lights, it's much much faster. but i don't even see the lamps you're talking about, they aren't visible in the render. there's one over the dining room table, but it isn't even glowing.

i believe (but i haven't really tested this) that point lights take more time than rectangular lights (although cleaning up the blurry shadows can add to render time). regardless, you can't need 17 lights at the interior of that scene.

[Micha]

i believe (but i haven't really tested this) that point lights take more time than rectangular lights (although cleaning up the blurry shadows can add to render time).

I use the rectangular light option "use IM" always, so I prefer this light type too.

[Helldoor]

Render Results

Hi there.


I've tested the tipps you gave me for the render settings. Once is for sure - they helped a lot! Thanks, guys!
The output size is the same, I used for my 13 Hour session - 1850 x 1307.
And the the render options are set after your recommendations.

I'll be glad to hear your opinions about the quality to render time ratio...
Here the results:

Pic 1: fooprobe : 2h 54min
Pic 2: Micha : 1h 12min
Pic 3: Rob : 7h 9min

[Micha]

Some time if I did render tests and compared two versions than I found differences, but most I thought, if there would no comparison image than I wouldn't see small errors or little disadvantages. So, I would take the lowest render time.

If you like to get some better details at my version I would adjust the ambient occlusion (AO) at the GI settings. So you could get better shadow edges at the upper outside of balcony (there I see a little difference to the fooprobe version).