Split-Frame Rendering

Overview

The ResPower Super/Farm™ is capable of rendering large-format or exceedingly slow-to-render still images by distributing them across the farm. This process is called Split-Frame™ Rendering.

Split-frame rendering works with the following software:

• 3dStudio Max 5.x, 6.x, 7.x, 8.x
• Brazil R/S
• finalRender Stage-1
• mental ray Use the ResPower Super/Farmer™ to specify split-frame rendering for 3dstudio Max
• LightWave
• Maya
• Maya Software
• mental ray

Split-Frame rendering is not appropriate for most animations, because the added overhead generally outweighs the benefit. In most cases, you should only use Split-Frame rendering to accelerate large format or exceedingly slow-to-render still images.

Technical Background

In order to render a still image across the farm, the ResPower Render Farm divides the image into a grid of "buckets" and then schedules processors to render each individual bucket. The result is that the buckets then render concurrently and the overall render time is drastically reduced. Once the render is complete, you can simply download each bucket's output file and reassemble the completed image in your favorite photo editor.

Step-By-Step Instructions:

• 3dStudio Max
• Lightwave
• Maya

Advanced Discussion

The number of buckets that you split your render into has an effect on bucket-render-time, total-render-time, and customer wait time.

• Bucket-render-time is the time required to render any individual bucket.
• Total-render-time is the sum of all the buckets' render times.
• Customer wait time is time between the start of the render and completion of the final bucket.

More buckets results in each individual bucket being smaller which leads to shorter bucket-render-times. However, the overhead associated with this can end up leading to a longer wait time. For example, with 250 buckets you might experience a bucket-render-time of 5 minutes per bucket. With the same image split into 1000 buckets, you might experience a bucket-render-time of 4 minutes per bucket. In the first case, your total render time is 250 * 5 = 1250 minutes, while in the second case, it is 1000 * 4 = 4000 minutes. Note: these times are not in any way indicative of actual render times you can expect. Every image is different and renders in a different amount of time.

This can end up affecting customer wait time as well. For example, if you split your render up 250 ways you might intuitively expect it to render exactly 250 times faster than it would on one computer. This is not the case because you now load the image 250 times, along with the textures, objects, and other miscellaneous data required to render it. In practice, then, it may render 240 times faster instead of 250 times. The actual difference in customer wait time between the ideal and reality depends at least partially on the number of buckets. If you split your image up into too many buckets you run the risk of increasing the effects of overhead and thus, stretching out your wait time.

In general, ResPower suggests that you split your image up into at most 40 buckets, primarily because if you split your frame up further you run a greater risk of defeating the purpose of split frame rendering.