V-Ray on Render-Farm: Progressive or Bucket?

It depends on the project which Image Sampler to use when rendering in V-Ray. Studios develop their own pipelines and use each sampler for a specific task. Freelance visualizers often use just one of them out of convenience or habit. But when you are working with the render-farm, you should understand the difference between Progressive and Bucket Image Samplers.

Progressive Image Sampler works similarly to Corona Renderer. It starts creating the image as a whole and refines it with each pass until the noise level lowers to the set value or the user stops it manually. On the other hand, Bucket Image Sampler segments the image into squares – buckets – and renders each square separately. Depending on the amount of CPU threads, several buckets could be rendered at once.

Progressive Image Sampler is popular because it immediately shows the whole image, and rendering can be stopped right away, if you see missing materials or objects in the scene. It is also often used for rendering animation previews, as you can set a time limit for each frame. Progressive can be used for final rendering too: it is stopped, when the noise level reaches an acceptable level, and then the denoiser is applied.

Progressive Image Sampler after 8 seconds and after 6 minutes and 25 seconds	Bucket Image Sampler during rendering and the final result

But you should be careful when using Progressive on the render-farm as it has certain disadvantages:

1. This type of rendering doesn’t 100% load CPU cores, which leads to you overpaying for processor working only at a part of its capacity.

2. Progressive Image Sampler doesn’t work well in distributed rendering (when several servers are rendering one image together). It spends a lot of time exchanging information between servers, while the rendering is put on hold. On the contrary, Bucket Image Sampler was created with DR in mind.

3. In case of server going offline, Progressive rendering will get stuck in standby indefinitely, while Bucket rendering has recovering mechanisms.

4. Progressive rendering requires more RAM, which means you’ll have to wait longer for more powerful servers to be available.

To summarize:

Use Progressive Image Sampler for rendering previews to check that your scene got imported correctly to the render-farm, and for rendering animation previews. You can watch you rendering in real time by clicking “Preview” button in online-service.

Use Bucket Image Sampler to render your final image or animation, as it is more stable and effective and provides tools for recovering the image.

Start working with Megarender by signing up for our online-service. You can find the answers to your questions about how we work in our knowledge database or by contacting tech support who are available 24/7.