Doc:Manual/Render/Performances

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Manual - Blender 2.46

[edit] Rendering Big Hairy Scenes or Speeding Up Rendering

"A watched pot never boils" is the old saying, but you may wonder why your render takes so long to create, or worse, crashes mid-way through! Well, there is lots going on and lots you can do to speed up rendering or enable a complicated render to complete. Also, it is possible to render a very complicated scene on a mediocre PC by being "render-smart". Here's a "top ten" list of things to do or not do in order to speed up rendering or even avoid crashes on scene render. Some options may decrease the quality of your render, but for draft renders you may not care.

If you get the message "Malloc returns nil", in plain english that means the memory allocator tried to get more physical memory for Blender but came back empty-handed. This means that you do not have enough memory available to render the scene, and Blender cannot continue. You will need to do one or more of the following tasks on this page in order to render.

[edit] Hardware Improvements

1. Get more RAM up to your PC's (motherboard and operating system) limit. Presently, Blender can use up to 8GG (giga-giga) of physical memory (64-bit address space), but most PC's can only handle 2G of RAM.
2. Upgrade your CPU to a multi-core/multiprocessor
3. Upgrade your OpenGL video drivers
4. Get a faster memory bus
5. Get faster memory, up to yor PC's motherboard limit. 667MHz memory is 30% slower than 800MHz.
6. Use or set up a render farm using all available PC's in your house, or use a render farm such as BURP.

[edit] Operating System Configuration

1. Increase the processing priority through your OS
2. Increase your swap file space used by the OS for memory swapping. Also called virtual memory pagefile size, up to the size of your physical memory.
3. Upgrade to a 64-bit operating system
4. Exit or stop any background processes, like virus scanners, BOINC, Real, even "inactive" ones like Quicktime, as they can randomly start up to look for updates. They also take up RAM.
5. Disable network connections to stop random pinging traffic and refresh traffic
6. Stop listening to internet radio and close web browsers, especially any multi-media (audio/video/game) sites.
7. Close down all other running applications, like Word
8. Exit all TSRs (those icons on your system tray) and widgets, any background processes, and virus scanners

[edit] Blender Choices

1. Increase the MEM Cache Limit in the User Preferences System & OpenGL tab
2. Upgrade to an optimized Blender build, especially if you have a modern chip that supports SSE2 - render times are 30% faster using an optimized build.
3. Switch to an Orthographic camera, and render your own "parts" of the scene as separate images, and then paste those parts together in GIMP. An old trick in making your own panoramic with a real camera is to take three or so pictures of a very wide (beach sunset) scene, where you take one picture, rotate to the right, snap another, then another, and when you get the pictures developed, you overlap them to make a very wide landscape image. Do the same in Blender; render out one shot to a file, then move the camera to look at a different area of the scene, and render that shot. Each shot will be of a smaller area and thus take in fewer polygons/faces. Be sure that when you position your camera that you snap overlapping shots, so that you can then match them up. If you don't want to use GIMP, you can use compositing nodes and the Translate node to match them up in Blender.
4. Minimize the render window (and Blender if rendering to an internal window). ATI users report dramatic speedup on a per frame basis, which adds up over frame range.
5. Use the Big Render script to render sub-sections of the overall image, and then paste them together.

[edit] Scene and Specific Objects

1. Remove lamps, or move them to un-rendered layers, or tie them to layers
2. Turn off some lamp's shadows, using only one or two main sun lamps to cast shadows. A few "shadows only" lights will render faster than every light having shadows on.
3. Use Buffer Shadows rather than Raytraced Shadows
4. Bake your shadows using Render Baking Full Render bake on surfaces that do not move. Using that texture for that mesh, then disable shadows for that material.
5. Simplify meshes (remove polygons). The more vertices you have in camera, the more time it takes to render.
6. Remove Doubles, or use the Decimator mesh edit feature.
7. Remove Subsurf and Multires modifiers
8. Delete backsides of meshes (removing unseen vertices)
9. Render just a few objects at a time; in the beginning of your project, render the background objects and set that will not change and will always be in the background.
10. Put the buildings on another layer, and through renderlayers, don't render them. Then composite them back in later.
11. Make the camera static so that you can better accomplish the above two ideas.
12. Avoid use of Area lights
13. Make materials Shadeless
14. Render Bake AO and textures, and then make those materials Shadeless
15. Decrease the Clip distance for spot lights
16. Decrease the Clip distance for the camera
17. Turn off world AO
18. Turn off Material SSS
19. Use smaller image textures. A 256x256 image takes only 1% of the memory that a 2k image does, often with no loss of quality in the ulitmate render.
20. Reduce Subsurf. Each level quadruples (4x) the number of faces from the previous level.
21. Reduce Multires
22. Make a matte render of background objects, like buildings, and put the image of them on a billboard in the scene instead of the object themselves. This will reduce vertex/face count

[edit] Render Settings

• Output Panel
  1. Disable Edge rendering.
  2. Save Buffers
  3. Render to an Image Editor window, not a popup Render Window.
  4. Use multiple Threads on a multi-core CPU (with multiple Parts).
• Render Layers Panel
  1. Render only the Layers of interest.
  2. Render with all lights set to one simple spot (enter its name in the Light: field)
  3. Render with one material override (enter its name in the Mat: field)
  4. Disable unnecessary Render Passes, such as Z, or only render the pass of interest, such as Diffuse.
• Render Panel
  1. Turn off Shadows
  2. Turn off Environment Mapping
  3. Turn off Panoramic Rendering
  4. Turn off Raytracing
  5. Turn off Radiosity
  6. Turn off SSS Subsurface Scattering
  7. Turn off or lower oversampling/aliasing OSA
  8. Turn off or lower Motion Blur
  9. Render in Parts. This will also allow you to render HUGE images on a weak PC. On a multi-core PC, it will assign a thread to each part as well.
  10. Increase the octree resolution
  11. Render at a percentage size of your final resolution (like 25%)
  12. Turn off Fields rendering.
  13. Use Border rendering to render a subset of the full image.
• Anim Panel
  1. Decrease the frame count of the animation (and use a lower framerate for the same duration of animation). For example, render 30 frames at 10 frames per second for a 3-second animation, instead of 75 frames at 25 frames per second.
• Bake Panel
  1. Bake Full Render - create a UV Texture that colors the objects based on materials, and then use that UV Texture shadeless instead of the material - 7x faster:
     
     
     
  2. Bake Ambient Occlusion only
  3. Bake textures for objects
  4. Baking Normals or Displacement does not speed up render time, and are used for other things.
• Format Panel
  1. Render at a lower resolution. Smaller pictures take less time to render.
  2. Choose a faster CODEC or CODEC settings
  3. Render in black and white (BW button)
  4. If using FFMPEG, do not activate Multiplex audio
  5. If using FFMPEG, Autosplit Output (Video panel button)
  6. Render only RGB if you need color; the A channel (RGBA button) takes more memory and is unused when saving a movie file.

Manual