Understanding render times - Sampling Focus

[Fluid_Jamie]

Hi Everyone,

I'm in the process of creating a 4500 frame fly-through animation for a client and have the time to debug render times, so thought I would turn to here for some advice! With the amount of frames involved, I'm keen to shave off as much on the render times as possible.

A large portion of the frames are relatively stable at 15/20mins per frame at 1080p, at a 5.0 noise limit. However some of the foliage heavy spaces are climbing to almost 50 minutes, so I'm trying to understand what I can do. Especially considering I want to reduce the noise limit for the final production.

I'm pretty sure it's down to the forest pack and the trees, as most of the buildings have very basic reflections and render very quickly when isolated. The trees were specified by the landscape architect and have been sourced from xfrog and evermotion, all of which rely on opacity mapped leaves. I have gone through and reduced reflections but the Sampling focus pass (attached) still highlights the trees as a source of concern. So do you guys have any suggestions on this?

The indirect light pass also showed a lot more noise than the direct, yet increasing the GI vs AA balance resulted in increased render times.

So, if anyone has any tips to help, it would be greatly appreciated. The scene is lit with a single PG HDRI, so no overly complex lighting. I'm sure there's something I've missed so let me know if there's any other info I can provide.

TL;DR - Need help with long render times, see attached passes!

Many Thanks,

Jamie

[vansan]

If I had the same problem I'd try to override GI material with the most simple (gray 210,210,210) color for every scene material (except glass).
Another way is to try baking indirect lighting using standard 3dsmax tools(never tried that though), and then render only direct lighting in animation.
And I hope you find your own way to improve rendertimes, and share it with us!

[FrostKiwi]

If you plan on going for such drastic optimisations, like overriding GI material you might want to jump to the newest daily build before doing so.
If you are not already, since there have been quite the big speedups in the recent days.

• Added new and improved image sampler, capable up to 100% speedups, on by default for all new and old scenes

• Another significant speedup due to better sampling: scenes with glossy surfaces clean up faster, hair renders much faster and no longer produces faint colored fireflies

[Fluid_Jamie]

Thanks guys, appreciate the advice. The improvements found in the daily builds do look impressive, however this project will eventually be going to a farm so that could throw up a few issues. And unfortunately 1.7 is due out the day of the project deadline...

I have a feeling that the slowdown is the opacity maps on the trees/bushes, as removing these from the scenes reduces the render times by over half.

Does anyone know of a method of rendering opacity maps faster? Without having to convert all the leaves to geometry!

[Bzuco]

To speed up foliage
https://forum.corona-renderer.com/index.php/topic,4537.msg73413.html#msg73413

Disable adaptivity, because it is mostly concentrating on not important parts in render (dark green leaves, dark bottom of house...human eye cannot recognize noise in dark colored areas very well)

[Bzuco]

If you consider that adaptivity is important for you, that at least increase Adaptivity recalculation value to something 2/3 of total passes. It will produce less noise on problematic parts(darker parts in sampling focus element)

[FrostKiwi]

Does anyone know of a method of rendering opacity maps faster? Without having to convert all the leaves to geometry!

In V-Ray there is a switch to binarize opacity maps. For leaves you can do a curve adjustment in the Output tab, so it is only 255 or 0 white. This gives a bit of a boost, albeit not as large as converting to geo.

[TomG]

In V-Ray there is a switch to binarize opacity maps. For leaves you can do a curve adjustment in the Output tab, so it is only 255 or 0 white. This gives a bit of a boost, albeit not as large as converting to geo.

You mean like the Clip option in the CoronaMtl for Opacity maps?

[romullus]

Make sure that opacity clip option is turned on in every material that has opacity map plugged in it. Also you can check if global opacity map filtering is turned off (should be off by default). One more thing you could try is to go through all your opacity maps and see if there's room for improvement in them - some textures are really bad prepared in that regard. Ideally you want as little black and as much pure white areas in your opacity map as possible. See attached image, from left to right: bad, better, best.

Ah crap, beatten by the two cowboys :]

[romullus]

To speed up foliage
https://forum.corona-renderer.com/index.php/topic,4537.msg73413.html#msg73413

I don't think that bit depth plays any significant part in Corona's rendering anymore. The issues raised in that topic was fixed long time ago.

Thanks guys, appreciate the advice. The improvements found in the daily builds do look impressive, however this project will eventually be going to a farm so that could throw up a few issues. And unfortunately 1.7 is due out the day of the project deadline...

There are some render farms that support daily builds. You may want to investigate that if you're not tied to some particular farm of course.

[FrostKiwi]

You mean like the Clip option in the CoronaMtl for Opacity maps?

Never work with foliage but Ohh wow, How did I totally overlook that one for all this time? O.o

[TomG]

You mean like the Clip option in the CoronaMtl for Opacity maps?

Never work with foliage but Ohh wow, How did I totally overlook that one for all this time? O.o

The clip option arrived with 1.5, you may just have overlooked it due to already having an established workflow :)

And on the cowboys from Romullus - yeeeehaaa! :) Lots of good info in here now and hopefully it will be of help for many!

[Fluid_Jamie]

You mean like the Clip option in the CoronaMtl for Opacity maps?

Never work with foliage but Ohh wow, How did I totally overlook that one for all this time? O.o

You're right, there's some really good info here. Thanks guys!

There are some render farms that support daily builds. You may want to investigate that if you're not tied to some particular farm of course.

I might have to go down this path, the potential speed increase sounds too good to ignore. I have a good relationship with my preferred farm so I'm sure they would be willing to help!

Make sure that opacity clip option is turned on in every material that has opacity map plugged in it. Also you can check if global opacity map filtering is turned off (should be off by default). One more thing you could try is to go through all your opacity maps and see if there's room for improvement in them - some textures are really bad prepared in that regard. Ideally you want as little black and as much pure white areas in your opacity map as possible. See attached image, from left to right: bad, better, best.

Ah crap, beatten by the two cowboys :]

Some really good tips there, thanks. I went through and turned clipping on for all opacity maps that were visible in the frame (including all the Forest Pack materials that are influence by the ForestEdge opacity map). However it hasn't made much of a difference, I presume as all the opacity maps were already 100% black or white.

Would you suggest the next step is reducing the surface area of the leaf geometry to match the bitmap? Some of the leaf shaders have an excessive bump map, but that shouldn't cause too much of an issue.

[romullus]

Would you suggest the next step is reducing the surface area of the leaf geometry to match the bitmap?

Well, that would be an ideal scenario, but hardly a practical one, especially when dealing with premade trees :] Adjusting bitmap or uv mapping is much easier task as usually there's only a few textures per asset. As you can see, the more opacity, the longer render times become.

Some of the leaf shaders have an excessive bump map, but that shouldn't cause too much of an issue.

Bump map may have significant impact on render time. You may want to turn it off on some bigger foliage assets and see if that would help.

[Fluid_Jamie]

Would you suggest the next step is reducing the surface area of the leaf geometry to match the bitmap?

Well, that would be an ideal scenario, but hardly a practical one, especially when dealing with premade trees :] Adjusting bitmap or uv mapping is much easier task as usually there's only a few textures per asset. As you can see, the more opacity, the longer render times become.

Especially since the leaves are one editable poly, not instanced objects. So I'm not even going to try altering hundreds of elements!

Some of the leaf shaders have an excessive bump map, but that shouldn't cause too much of an issue.

Bump map may have significant impact on render time. You may want to turn it off on some bigger foliage assets and see if that would help.

I've removed the bump, but I'm still experiencing high render times unfortunately! I could remove reflection from the leaves, but I don't want to lose too much realism!

I have found some of the leaves have unwanted translucency, and one model had 1.0 refraction in the leaves which made a big difference. I'll continue tweaking and see if I find anything else...