Houdini Engine Licenses for Batch Rendering: When You Need Them

The answer is any machine that runs Houdini without its interface, through hython or hbatch, has to check out a Houdini license, and Houdini Engine is the one SideFX intends for that job. It is the first license hython asks for and the cheapest commercial one that covers batch work. A machine that only renders a file somebody else already exported, an IFD for Mantra or a USD for Karma, draws a render license instead. So the count comes down to what each machine does. 

Image Source: Side FX

Because one license covers two different products. SideFX’s own license acquisition tables list them side by side: Houdini Engine in batch form, which is the hbatch and hython executables, and Houdini Engine in plug-in form, which opens inside a host application such as Unreal, Unity or Maya. Both request the same Houdini-Engine license.

The Houdini Engine product page says the same thing in plainer language. Engine works as a plug-in to other applications and as a non-graphical way to batch process and distribute work to a farm, and SideFX names rendering, dynamic simulation and geometry caching as typical batch tasks.

Both are Houdini without a window. hython runs Python scripts and hbatch runs HScript. The SideFX batch rendering page describes them as command line programs that let you do nearly everything the interface does, including triggering render nodes and generating IFD files.

Farms use them for three practical reasons. A render node usually has no display attached. A queue manager needs a command it can launch, monitor and kill. And nobody wants an interactive seat tied up on a machine that no artist is sitting at.

When hython starts in a commercial setup, the license system documentation says it checks for licenses in this order: Engine, then Core, then FX. Engine comes first because it suits the application and costs the least. FX sits last as a fallback.

Image Source: Side FX

Four licenses carry the Engine name, and only some of them run batch work. You can refer this table as shown below:

Count jobs, and the machine count follows. A license is checked out per machine, and which license depends on the program that machine is running at that moment.

SideFX gives the classic example in its batch rendering documentation. hbatch uses a Houdini license, while the mantra program rendering an IFD file uses only a render license. The page then describes a common setup: one host generates the IFD files with a single full license, and the rendering is farmed out to mantra instances on cheaper render licenses.

SideFX orders its license products in a hierarchy based on cost and features: FX above Core, Core above Engine. Most people read that as “a bigger license can stand in for a smaller one, in every direction”. The checkout rules are narrower than that.

Each application has its own list of licenses it is allowed to request. The license system documentation notes that some applications cannot check out specific licenses whatever options you set, and gives this example: “Houdini FX cannot checkout a Houdini Engine license.”

• hython can run on Engine, Core or FX, so an FX seat can do batch work.
• The interactive Houdini FX application cannot run on an Engine license, so a pile of Engine licenses will never open the interface.

The second point catches people during debugging. You remote into a render node to open the scene and see why a frame failed, and the interface refuses to start because the only licenses that machine can reach are Engine ones.

Engine Indie pairs with Indie files and assets, and the free Unreal and Unity license is commercial, so SideFX warns against mixing it into Indie or Education setups.

iRender currently offers both an RTX 4090 (24GB GDDR6X) and an RTX 5090 (32GB GDDR7), so this is a decision you can actually test rather than guess at. When you rent a machine from us, you get an empty remote workstation. You install Houdini yourself and you license it with your own account. iRender does not provide, lend or sell Houdini or Houdini Engine licenses. As the sections above show, the answer follows from how you organise your jobs, so ask SideFX about your specific setup before you scale.

This differs from a SaaS render farm, where you upload a scene and the operator’s cluster handles the software side. Here the environment is yours, which brings one real advantage for this topic. You can set up the exact license configuration you are entitled to use, run your hython or husk commands on a single machine, and watch which licenses get checked out before you add a second node. Testing a batch pipeline on one RTX 4090 or RTX 5090 machine with a Threadripper PRO CPU costs far less than discovering a license gap on ten.

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Q1: Do I need a Houdini Engine license to render on a farm?

In most setups, yes. Running Houdini without its interface through hython or hbatch requires a Houdini license, and Houdini Engine is the one SideFX intends for that work. The same Engine license covers both the plug-ins for host applications and the script-driven, windowless Houdini that farms run. hython can also run on a Core or FX seat, but that takes an interactive license away from an artist. Machines that only render an already exported IFD or USD file draw a render license instead. 

Q2: Is Houdini Engine free?

That varies with the version. According to SideFX, Houdini Engine for Unity and Unreal is a free commercial license, but it supports only those two plug-ins and cannot be used for batch processing or rendering. The paid Houdini Engine license supports all official Engine plug-ins, Hython, custom game engines, batch processing and USD file creation ahead of a Karma render. Houdini Engine Indie is free and works only with Houdini Indie files and assets. Houdini Engine Education comes with an Education license. Prices and limits change, so confirm them on the SideFX site.

Q3: How many licenses do I need for my render nodes?

The number comes down to what each machine does, and it is rarely one license per machine across the board. A machine that opens the scene and cooks it with hython or hbatch needs a batch-capable license such as Houdini Engine. A machine that only renders an existing IFD file with mantra, or a USD file with husk and Karma, draws a render license instead. 

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