You need the settings on this object to calculate the actual fire and smoke simulation. The Pyro Emitter tag, or the identical Pyro Fuel tag, provide all important settings for the Emitter. The Pyro Output object is automatically created when the first Pyro Emitter tag or Pyro Fuel tag is created and provides functions for calculating a RAM cache or saving and loading .vdb cache files, among others. The actual settings for the Pyro simulation calculation can be found in the Simulation/Pyro tab of the Project Settings). You can also find these settings linked in the Pyro Scene tab of the Pyro Output object or - as an independent instance - also with the Simulation Scene object.

Linking the Pyro presets from the Project Settings to the Pyro Output object makes it possible to have several Pyro Output objects in the scene and, for example, to create different caches of the same simulation. On the introduction page to the Pyro Simulation System you will find an example of this at here.

As mentioned earlier, the Pyro Output object can also save the simulations to a .vdb cache file, which can then be used for rendering or further processing in other programs. Likewise, the Pyro Output object can have the simulation saved to RAM, which then allows, for example, faster playback when playing in the Viewports or even rendering the simulation.

The relationship between the Pyro tags, Pyro objects, and Pyro Scene settings and the final rendering therefore looks like this:

• Select the object (polygon object or spline object) that will serve as the emitter for the simulation and assign the Pyro Emitter tag or Pyro Fuel tag to this object.
• Use the settings on the Pyro Emitter or Pyro Fuel tag and the Pyro Scene settings linked on the Pyro Output object to set up the simulation. You can also access these settings at any time using the keyboard shortcut Ctrl+D in the Attribute Manager.
• In the Viewport, an accurate preview of the simulation is already displayed when the time is played. Be sure to use a shading rendering mode, such as Constant Shading, Quick Shading, or Gouraud Shading.
• To examine a rendering of the simulation, enable the Density and Temperature options on the Pyro Output object and then run the simulation over time. This creates a RAM cache of these properties of the simulation.
• If you only want to render in the Image Manager or Redshift RenderView and do not want to perform test renderings in the Viewports as well, you can also switch the desired properties on the Pyro Output object to On Export. In this case, too, a RAM cache is created, but it only builds up when the rendering is started in the Image Manager or Redshift RenderView.
• Enable Redshift as the renderer in the render presets, and then have it create a Pyro Volume material (e.g., in the Material Manager via Create>Redshift>Materials>Pyro Volume). Assign this material directly to the Pyro Output object. Since the simulation channels for density and temperature are already entered correctly in this material, it is now possible to render directly with Redshift.
• Important: The simulation now in memory is not saved with the scene. After reopening this scene, the cache must therefore be created again by running the animation time. To avoid this, the cache can also be saved. This is detailed in the following section.

A second variant looks like this:

• Assign a Pyro Emitter tag to an object and configure the simulation there and in the Pyro Scene settings of the Pyro Output object according to your wishes, as it was also described above. Examine the preview of the simulation in the Viewport.
• When you are satisfied with the simulation, you can also use the Pyro Output object to have cache files saved for the required components of the simulation (for example, for the Density and Temperature of the simulation) by selecting these properties with On Export and then using the Calculate function in the object's cache settings. This means that this simulation can, for example, also be used later in other projects or even in other 3D programs that can handle simulation data.
• Select Redshift as the active renderer in the Render Settings to be able to call up the required volume materials (e.g., in the Material Manager via Create>Redshift>Materials>Pyro Volume) and also to have access to the Redshift Volume object if required.
• The Pyro Emitter tag can then be disabled. The simulation is automatically loaded from the cache files by the Pyro Output object. Accordingly, this object can then also be assigned, for example, the Redshift Pyro Volume material for rendering.
• Alternatively, you can do without the Pyro Output object and the Pyro Emitter tag altogether and instead use the Redshift Volume object, for example, to load the simulation, which then also has to be assigned the Redshift Volume or Redshift Pyro Volume material.
• When using the Redshift Volume object, enter the storage path to the .vdb cache file there. Since this will usually be a sequence of files, specify only the first cache file of the sequence here and also enter the correct frame rate and number of files.
• Make sure that the names of the simulation channels from the cache file are entered correctly in the Redshift Volume materials used, e.g., 'density' for density and 'temperature' for temperature. The available channels of the loaded cache file can be read directly in the Information area of the RS Volume object.
• From this moment on, you can render the simulation or elaborate the representation of the simulation using the Volume material.