Reducing Rendering Time

The most effective way to reduce rendering time is to use a fast computer. This means a computer that can process floating point calculations quickly. This generally is a computer with a newer, fast CPU. It is also important to have plenty of memory (RAM). If the computer runs out of physical memory it will use virtual memory. This is an area of the hard disk used for memory, and compared to the speed of the CPU, using virtual memory is extremely slow. Using virtual memory when rendering is very impractical. If you computer is constantly using virtual memory, it is highly recommended to install additional physical memory (RAM).

A fast graphics card will speed up drawing in the Figure Window but will have little benefit when rendering.

Below are some ways in which you may be able to reduce render times at the software level. Of course, the trade-off with rendering higher-quality images is always longer render times.

Reduce the CPU Load

• To the extent possible use the default values for all settings.
• Switch the rendering method from Path Tracing to Ray Tracing, or from Ray Tracing to Ray Tracing (Draft). Path Tracing takes several times longer to complete than Ray Tracing.
• Avoid using higher antialiasing, Ray Cast Level, and Ray Tracing Quality settings unnecessarily.
• When possible, avoid using the Reflection, Transparency, Refraction, and Roughness surface attributes, and the Solid Texture Turbulence attribute.
• Try not to use too many lights in the scene. Alternatively, set Shadows for extra lights to 0. (Leave shadows on for the main light source.) Setting the shadows to zero is very effective at reducing the CPU load.
• Regarding background settings, when not reflecting the background on objects or using transparency, consider using a composite or backdrop.
• Instead of using antialiasing, rendering a large image and then reducing its size in image editing software may also reduce the render time.
• When rendering animations, skip antialiasing or use lower-quality antialiasing.

Reduce Memory Requirements

• Reduce the level of surface subdivision. Just one level lower will cut the amount of memory used by approximately three-fourths. Put another way, Very Fine requires about 64 times more memory than Coarse.
  By lowering the subdivision level for the scene as a whole in the Rendering Settings and adding the < character to the front of the name of only those shapes that need to be rendered in finer detail, surface subdivision can be used very efficiently.
  When using displacement maps, lower the level of subdivision.
• As much as possible avoid converting spheres and revolved solids to curved surfaces. There is a considerable difference in scenes with many spheres or revolved solids.
• Avoid creating lots of unnecessary parts.
• When using image maps, avoid using unnecessarily-large images. When mapping the same image to multiple shapes, put the shapes inside a part and apply mapping to that part. If the shapes cannot be put inside a single part, use a master surface.
• Decrease the size of the rendered image.
• Close other applications that are not in use.