This page provides details on using V-Ray's Resumable Rendering feature.
Resumable rendering is the ability to have incomplete renders resume where they left off from the previous session. The rendering may have stopped due to any number of reasons such as a power failure or having the job bumped off a machine or a render farm, or perhaps you stopped the render manually and want to start from where you left off.
For details on the V-Ray Common tab page under the Render Settings window.
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How it works
Resumable renders are possible with both Bucket and Progressive Image Sampler types.
With Bucket rendering, an additional .vrimg is written, storing the data of the completed buckets. When resuming the render, V-Ray reads the .vrimg file to determine which buckets still need to be rendered and continues to calculate what is left to complete the image. Another great ability of this feature is that the Light Cache data is saved within the partial image file so that the light cache does not need to be recalculated when the render resumes.
When rendering with the Progressive image sampler, the state of the render is saved to an additional resumable .vrprog file, in a similar way to the .vrimg for Bucket rendering. Setting Autosave Interval (min) from the Image File Output rollout of the Render Settings Common tab (to anything higher than 0) is useful so V-Ray can write out the .vrprog files during rendering, in case the process is unintentionally stopped. However, setting the Autosave Interval (min) value too low (below a couple of minutes for example) may slow the render process.
If V-Ray finds a .vrprog file or a partially completed .vrimg file for the current frame, the rendering resumes from where it left off. If not, V-Ray starts a new render and a resumable file is then saved.
- Light Cache data is saved in the resumable files, but the Irradiance Map (or any other GI map) is not, and will need to be recalculated when resuming the render. The rendering should still continue from where it was stopped, after the GI data is recalculated.
- The Resumable Rendering option should be enabled before starting a new render, not only when resuming.
- To start a new render, the .vrimg/.vrprog file should be deleted.
- The scene should not be changed between stopping and resuming, except for the Progressive sampling options (Min. subdivs, Max. subdivs, Max Render time, Noise threshold).
- There are two output modes that are not currently supported for the Bucket Sampler - deep output, and tiled EXR output (without a memory frame buffer).