Introduction to Distributed Rendering
With Corona’s Distributed Rendering, you can significantly speed up your image rendering by harnessing the power of multiple computers working together over a single network. Each machine contributes to the same render, sharing the workload and reducing overall render time. While this technology is commonly used in commercial render farms, anyone with access to more than one computer can take advantage of it.
The performance boost is typically close to linear scaling—for example, if one computer renders an image in 10 minutes, two identical machines can complete the same task in roughly 5 minutes.
Keep in mind, however, that there can be a slight time overhead, particularly when dealing with very large or high-resolution scenes. This is due to bandwidth limitations when transferring scene data and rendered pixels between the main workstation and the render nodes.
In short: if you have access to more than one computer, you can use Corona's Distributed Rendering to render your images faster!
Important note: Corona’s Distributed Rendering is best suited for situations where multiple computers work together to render a single image (as described later in this guide). If your goal is to render an animation or a sequence of frames, where each computer handles a different frame, it’s recommended to use alternative network rendering solutions—such as Autodesk Backburner or other third-party render management tools—for optimal performance and workflow efficiency.
Distributed Rendering Requirements
You must have all of the following applications installed:
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On the render nodes and the master workstation: Corona for 3ds Max - it is best to use the newest version available at https://www.chaos.com/corona/download
Note: the exact same version of Corona needs to be installed on all machines taking part in distributed rendering!
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On the render nodes and the master workstation: 3ds Max - any version supported by your current Corona version
Note: the exact same version of 3ds Max needs to be installed on all machines taking part in distributed rendering!
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On the render nodes and the master workstation: Autodesk Backburner - download here
Note: Autodesk Backburner is not directly used in Corona's Distributed Rendering process but it is required for it to work correctly.
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On the render nodes: Corona DR Server - it is included in the Universal Installer, and by default it is installed into C:\Program Files\Chaos\Corona\Corona Renderer for 3ds Max\DR Server\DrServer.exe
For Backburner installation/uninstallation troubleshooting, see: Distributed Rendering does not work - "Unknown error while loading application"
Further requirements:
- DrServer.exe must be running on all render nodes
- All render nodes must be on the same LAN network and sub-network
- Both 3dsmax.exe and DrServer.exe must be allowed to communicate (both incoming and outgoing connections) on these two ports: TCP 19667 and TCP 19668. Sometimes adjusting firewall settings may be necessary
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Both the workstations and the render nodes taking part in the distributed rendering must have Corona licenses active!
See: Activating Corona for 3ds Max - 3ds Max does not have to be activated on the render nodes. You may use the trial license, or even an expired trial license and that is absolutely fine with Autodesk licensing terms as 3ds Max will be used in command line mode only, without the user interface visible.
Using Distributed Rendering
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On all render nodes: run the DrServer application
Note: the DrServer must not be running with elevation (it must not be running "as administrator").
Do not run DrServer on the master workstation!
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On the master workstation: in 3ds Max, go to Render Setup > System > Distributed Rendering, tick the "Enable" checkbox, and press "Search LAN":
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On the master workstation: wait for the addresses or names of your render nodes to appear on the list (or enter their network names or IPs manually using the "Add" button at the bottom):
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On the master workstation: start rendering:
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On all render nodes: a new 3ds Max instance should appear after some time (minimized, so you won't be able to see its UI or the VFB), then it should start rendering your scene, and sending rendered data to the master workstation based on the "Synchronization interval" time specified in the Distributed Rendering rollout.
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On the master workstation: you can see Distributed Rendering information in the DR tab of the Corona VFB:
Note: you can also check the "Search LAN during render" option in the Distributed Redering rollout on the master workstation to make Corona search for any machines with the DrServer application running and automatically add them to the rendering even after it has already started. As a result, any machines where the DrServer application was launched at some point during rendering will join, and any machines where the rendering was interrupted due to an error or user intervention will be able to re-join the rendering again.
The rendering will stop after it reaches the given render limit, or after you stop it manually on the master computer. In case of render limits, each limit is considered based the master machine statistics, not for each of the render nodes. For example, if you set the limit to 10 minutes, the rendering will stop after 10 minutes pass on the master machine, not on the render nodes. If you set it to 100 passes, it will stop once the total number of passes reported on the master machine reaches 100, regardless of how many passes each render node has rendered. If you use the noise limit, it will stop once the target noise level is reached on the master machine.
Distributed Rendering Troubleshooting
Note: the error messaging system will catch known issues and will warn you about any detected problems. This is often helpful for troubleshooting.- First diagnostic step when experiencing DR issues is always disabling all installed antivirus / firewall software on both the master workstation and the render node machines.
This does not mean that antivirus / firewall software should be always disabled when using DR. But disabling it can verify if the issue is related to this software at all. If so, then further steps can be made to fix the issue. The usual solution is adding custom rules to Windows Firewall to allow Corona's DR. See: Creating custom inbound and outbound rules
- If the master machine is detecting the nodes, but the nodes are not starting the rendering for an unknown reason (there are no error messages, no information in the logs), please try the following if possible:
- Download and install Autodesk Access (formerly Autodesk Desktop App) and sign into it with your Autodesk credentials: https://www.autodesk.com/products/autodesk-access/overview
- Launch 3ds Max on each node and make sure it starts normally (there are no error messages, missing plugin warnings, requests to activate the license, etc).
- One common problem can be related to the paging file settings on your render nodes. If a node is set to use custom paging file settings with low values, it might run out of memory during rendering.
- Solution: Windows uses a paging file (also known as virtual memory) to supplement the physical RAM when needed. This file is stored on the hard drive and helps manage memory for running applications. The paging file is used when the physical RAM is fully utilized or for efficient memory management, even if some RAM is still available. If the paging file is set incorrectly, it can cause rendering issues even when there seems to be enough physical RAM available. To avoid this, make sure that the paging file setting on all nodes is set to "System Managed". To do this, go to Windows Advanced system settings > Performance > Settings > Advanced > Virtual memory > Change..., then check "Automatically manage paging file size for all drives".
- Using DR with a VPN
- "Unknown error while loading application" message
- Missing assets when DR server is running in administrator mode
Useful links
- "Creating a Render Farm" forum thread - https://corona-renderer.com/forum/index.php/topic,12173.0.html
- General guide on reporting issues - How to report issues