PDA

View Full Version : Overcoming high render times



HolyMonkey-
01-30-2012, 07:49 AM
Alright, I've opened quite alot of thread lately, hope thats alright, and useful for other people than me! Anyhoo back to buisness

In general , rendertimes do really well, until I add in reflection and reflection blur in the shaders.

After radiosity bake, rendertime can be somewhere in between 10-20minutes per frame. Is this normal for a sequence?

Is the only way to overcome this is to bake out cache and put it in a renderfarm?

What im trying to ask is, if there is any way of optimizing a render with reflections and what not, in order to get decent rendertimes under the 10 minute mark.

Cheerio!

mummyman
01-30-2012, 08:00 AM
Maybe look into compositing the reflections and blur them in post??

cptwhite
01-30-2012, 10:02 AM
I'm not an advanced user but can tell you render time is going to be greatly affected by:

Image size in pixels

The amount of AA to you (and type - have you tried Adaptive AA settings with the perspective camera - set AA to 1, and Adaptive AA to 0.05, and oversample to 0.2 and see what you think of the result...the lower the Adaptive AA value the better the render), oversample adds a kind of "softening" to the final render but it's very subtle.)

Reflection blurring is a killer for render times, you might be able to get better results through the node editor, depending on what material you're trying to emulate

The radiosity settings will also greatly affect render time, what type are you using, is it indoor, outdoor...have you followed the radiosity guide on in order to optimise your settings?

Following on from that, are you working in a linear workflow as this helps reduce the quality settings required in radiosity for faster results. Read up on this if you don't know much about it - highly recommended! Basically you should be de-gamma-ing any 8 bit RGB textures before using within lightwave, then re-gamma-ing the result after render (easy in LW 10 - go to Edit > Colour Space Options). Search for official newtek video on Linear Workflow for a decent explaination on youtube (there's a 10 minute vid of this feature).

Finally what are your light sources for global illuminations? I highly recommend you download sIBL (from [url]www.hdrlabs.com (http://www.except.nl/lightwave/RadiosityGuide96/index.htm
except.nl[/url)). There's a plugin for lightwave, download some sIBL (smart image based lighting) from the archive and apply - gives very nice lighting results, tweak the radiosity intensity value to suit the background you use :)

Good luck :)

HolyMonkey-
01-31-2012, 01:23 AM
I'm not an advanced user but can tell you render time is going to be greatly affected by:

Image size in pixels

The amount of AA to you (and type - have you tried Adaptive AA settings with the perspective camera - set AA to 1, and Adaptive AA to 0.05, and oversample to 0.2 and see what you think of the result...the lower the Adaptive AA value the better the render), oversample adds a kind of "softening" to the final render but it's very subtle.)

Reflection blurring is a killer for render times, you might be able to get better results through the node editor, depending on what material you're trying to emulate

The radiosity settings will also greatly affect render time, what type are you using, is it indoor, outdoor...have you followed the radiosity guide on in order to optimise your settings?

Following on from that, are you working in a linear workflow as this helps reduce the quality settings required in radiosity for faster results. Read up on this if you don't know much about it - highly recommended! Basically you should be de-gamma-ing any 8 bit RGB textures before using within lightwave, then re-gamma-ing the result after render (easy in LW 10 - go to Edit > Colour Space Options). Search for official newtek video on Linear Workflow for a decent explaination on youtube (there's a 10 minute vid of this feature).

Finally what are your light sources for global illuminations? I highly recommend you download sIBL (from [url]www.hdrlabs.com (http://www.except.nl/lightwave/RadiosityGuide96/index.htm
except.nl[/url)). There's a plugin for lightwave, download some sIBL (smart image based lighting) from the archive and apply - gives very nice lighting results, tweak the radiosity intensity value to suit the background you use :)

Good luck :)

I love this forum, great help! Thanks! =) and thanks to you mummyman!

cptwhite
01-31-2012, 02:47 AM
Let us know how you get on HolyMonkey, including detailed info about your settings (before and after). How you optimised and examples of the render times, always useful for others who may read this :)

Surrealist.
01-31-2012, 02:57 AM
Well to answer your initial question, yes, it is normal. But of course this is scene dependent.

I think to get quality, you are looking at render time. This is just one of those things you have to accept.

You can do a lot to optimize your scene, so it could be that if you have a very simple scene and it is taking a lot longer than it should then, optimization (as in the suggestions above) will help. But the bottom line is, once your scene gets complex, that is to say, once you start making a scene that you'll likely use for a production, with some quality and anything other than just one object sitting on the floor, you are looking at high render times.

Global illumination with Interpolated in LightWave is fairly fast but it is limited to camera and object movement and will not work for deformed objects/characters. So that is another hurdle.

I have heard it said once that studio production render times range from 30 to 90 minutes per frame. And I am fairly sure that in some cases it is much higher than that for photo realistic complex special effects. That seems reasonable to me considering a fair amount of complexity. The only real answer is to beef up your rendering hardware - render farm etc.

There are other alternatives that all lead up to a sacrifice in quality. So it is a trade off. Obviously none of this is a hard rule. No two scenes are going to be the same. But I think if you want any quality at all you just have to accept the render time hit, like anything else in 3D (cloth simulation, dynamics, modeling, texturing) - quality/time/money.

JonW
01-31-2012, 03:55 AM
If there is a lot of reflections & transparency & you want flicker free & overall good quality. 30 minutes a frame would be reasonable. Obviously if your box has a pair of X5690 CPUs it's going to render a frame 4 x quicker than a 920 CPU.

The quickest way to reduce frame render time, is to get another computer or 3 onto the job!

HolyMonkey-
01-31-2012, 05:00 AM
If there is a lot of reflections & transparency & you want flicker free & overall good quality. 30 minutes a frame would be reasonable. Obviously if your box has a pair of X5690 CPUs it's going to render a frame 4 x quicker than a 920 CPU.

The quickest way to reduce frame render time, is to get another computer or 3 onto the job!

We have a renderfarm we're renting down in germany, but I haven't tried setting it up yet but I've come across quite a few threads where people have a few problems using renderfarms.

#1 The scene can't find the radiosity file, even if you put it to "locked" and keep it in the same directory.

#2 Does baking radisotiy down on many camera angles reduce render time?

F.ex You have one perspective camera which handles the main video, then you take a camera spinning around the object calculating radisoity.

Etc. Thank you all so much, this is of great help!

Surrealist.
01-31-2012, 05:55 AM
I have seen some of those radioisty threads too. I have not been using a render farm myself but I did see the solution bought about in one of the threads. It seems to be a bit tricky to get working, but possible.

I can echo what JohnW said. I have a scene that renders on my older quad core in about an hour. I had it tested on a newer 6 core machine and it rendered in about 10 minutes.

JonW
01-31-2012, 06:34 AM
You can use as many cameras as you want to bake radiosity & keep adding to the file. Then use as many different cameras as you want to render frames.

If radiosity is not been found on the farm you have a problem with a path to the file. It's happened to us all!

Read Matt Gorner's PDF (It's in the Screannet thread/ Screamernet tutorials/ first link!) on setting up a farm, & PRINT IT OFF & write down notes & highlight the important bits!

Practice with 1 additional computer first. When you iron out that problem, you will see then that it's easy to add more computers. Locate the SN folder/files in the same hierarchy on every computer & you can copy & paste nodes, & all you need to do is change the node number.

Make sure all your files-have-no_gaps_in_their-names!

HolyMonkey-
01-31-2012, 11:09 AM
You can use as many cameras as you want to bake radiosity & keep adding to the file. Then use as many different cameras as you want to render frames.

If radiosity is not been found on the farm you have a problem with a path to the file. It's happened to us all!

Read Matt Gorner's PDF (It's in the Screannet thread/ Screamernet tutorials/ first link!) on setting up a farm, & PRINT IT OFF & write down notes & highlight the important bits!

Practice with 1 additional computer first. When you iron out that problem, you will see then that it's easy to add more computers. Locate the SN folder/files in the same hierarchy on every computer & you can copy & paste nodes, & all you need to do is change the node number.

Make sure all your files-have-no_gaps_in_their-names!

Thanks, I read some people fixed the renderfarm issue by setting the path to the radisoity file manually opening up some file in nodepad or somethimg, are you familiar with this?

JonW
01-31-2012, 03:32 PM
Thanks, I read some people fixed the renderfarm issue by setting the path to the radisoity file manually opening up some file in nodepad or somethimg, are you familiar with this?

No.

I had to put the Radiosity file in the SN folder. I also bake then lock the file. If you are still having issue do half a dozen MB passes & you can drop back the radiosity settings a bit. Every scene is different & one just needs to work at it.

Radiosity on a single frame one can get away with murder, but with frames every frame is dependent on the next so quality needs to be a lot higher.

Get SN up & running when things are quite is the way to go.