Speeding up renders?

Ok, I tried to render an animation with somewhere around 300 frames. It was a pretty complex, scene, and I used Motion blur, raytracing, shadows and 8x antialising. I leaft my computer on all night and find it on frame 4. Is there a way to make the render time faster?

yep one way is to “cut” the screen into little segments this speeds up render time espesialy witha large scene the other way is if you have a multithread ing prosser you can up the amount of threads used. blender can handle 8 threads. and you can cut your screen 512 times in the y axis and 68 in the x or the other way around im can not remember from memery. both can be found in the render panle

The same as in the other thread:

Yes, there a way how to speed up rendering, read this: http://wiki.blender.org/index.php/Manual/Rendering#Decreasing_Render_Time

Also play with octree resolution. Depending on complexity of meshes and size of scene set the right octree resolution. Higher numbers works better with big scenes with detailed object far away. Just with it, it can increase/descrease the amount of time by 10 times in some cases.

What is a pretty complex scene? And what are your computer specs?

Break it out into passes.
Turn off motion blur.
Render your scene.
Then manipulate and add blur on top of that.
You could even go down to the level of only rendering out the object that is in motion and apply blur only to that object.

Turn your ray-trace count down to 1 or 2.

If it is a complex background scene that is mostly static, render out the background then create a new scene and use that background as an image with objects on top.

Instead of using Blender’s default motion blur, there is a method of producing vector blur, which only requires one calculation per frame and is included into the frame, meaning you don’t have to rendering it 5 times and composite it together.

I forget the node setup for Vector Blur, so if someone could enlighten me I’d appreciate it! :yes:


Ok, the scene is 3587624 polys. I have a 2 GigaHz processor, and 1.3 GB ram. I have achieved a reasonable render time through baking all of the reflections (all objects are shiny and reflective) onto a UV texture. BTW, the full scene is in motion all the time.

How did you bake the reflections? Created environment maps for them? Does the scene with textures and render output fit into the RAM, or is the swapping needed? Because 3.5M polys isn’t that small number, plus textures, renders.

What is the average time per frame?

How many cores does your processor have? Does it support hyperthreading? If you have only one core and no hyperthreading then increasing the number of blender threads to more than one will probably slow down your render overall. The same applies to the total number of parts (X times Y), unless memory is limited in which case more parts may help.

Your render will probably benefit more from scene-specific settings, like octree resolution and bake-related optimizations, as in earlier posts.

I baked the reflections to a UV map. The time for each frame is now around 20 seconds. It all fits into RAM if I am not running anything in front of it. If I run games in front of it the time per frame is 20 min.

20sec per Frame is actually pretty good. Considering you have a 300Frame animation and not taking into account that you have motion blur activated you will still need 100 mins or 1:40 hours.
When you have motionblur activated each frame will take longer since it will render the preceding and following frame ( I think). Using vector blur might increase the speed but you will have to see how frame render time changes.

Oh, forgot to mention, I slowed down the animation, so now it is over 700 frames. I also turned motoin blur off. Motion blur simply renders 5 intermediate frames (or more) then blends them together.


To do Vector Blur you have to turn on “Vec” under render layers. Then go to your compositor window, take the Image, Z Data, and Speed and plug it into the Vector Blur node which can be found under Filter.

In the end your setup should look similar to this:


Well, 20 seconds for frame is very good time, even if you want 700 of them. There is always the possibility to render into image sequence overnight and then make a video of them later.

I agree with Myn.pheos: 20 seconds is a very good per frame time. I wonder that the scene is so complex yet you need blur for everything. Doesn’t a lot of the modeled in detail get lost? You might try hiding everything that’s not in view during a sequence of frames to get even more speed, but the manual overhead to break the animation into segments might take longer than just letting it run.

One thing I would recommend, which you’ve probably already thought of, is to still render a dozen or so frames from various key points in the animation, to see what it will look like and avoid any surprises in the finished animation. Then, either render a series of images and turn them into an animation later, or kick off the animation overnight or when you are out.

If you have flash you could add motion blur in after, you would have to do an Image sequence though…
Could we see it when you’ve completed it? :slight_smile:
Just wondering.