Redshift Proxy in Houdini: Exporting and Using Proxies Efficiently

What does Redshift Proxy offer?

Redshift Proxy reduces the need to load all data into a Houdini scene when using previously exported geometry. Redshift loads the proxy geometry during rendering when a ray intersects the proxy’s bounding box. According to MAXON documentation, this approach can reduce the cost of processing large geometry again for every scene translation; proxy data is also stored on disk in an optimized format.

Using a proxy limits how editable the model is. Apart from tessellation settings, the exported geometry cannot be deformed or changed through the proxy file. The proxy as a whole can be moved, rotated, and scaled; to change its components, you need to edit the source data and export the proxy again. Since it is not possible to recover the original model mesh from a Redshift Proxy file, it is important to keep the source files.

This guide is based on MAXON’s Redshift documentation for Houdini. The source documentation does not specify the Houdini or Redshift version used, so the steps cannot be tied to a particular version number. Interface labels may vary by version, so use the parameter names given in the documentation as your reference.

1. Choose the right export node

Houdini documentation describes three different export methods. Redshift ROP can export full proxy scenes or selected objects; the documentation also gives the example of using it for complete scene files to be rendered on render farms. Redshift Proxy Output ROP creates proxy objects from a render context, while Redshift Proxy Output SOP exports data connected to a modeling SOP inside an OBJ and is limited to a single object.

1. Choose Redshift ROP, Proxy Output ROP, or Proxy Output SOP based on the scope of the content you want to export.

2. If you’re using Redshift ROP, enable Export .rs Proxy File in the Archive section.

3. Set the file location and name. Proxy files should use the .rs extension. If you’re exporting a frame sequence, use the $F frame token in the filename.

4. Start the export through Redshift ROP by clicking Render to Disk.

Export Only Selected Objects exports only selected objects in Redshift ROP. When Create Intermediate Directories is enabled, Houdini automatically creates the folders needed to save the files. These options are useful when planning export scope and output folders, but you should check which settings are supported by each node. The documentation specifically notes that some options apply only to Redshift ROP.

The choice to compress depends on transfer and storage speeds. MAXON notes that a smaller file may improve performance when a slow network or storage device is the bottleneck, while on a fast network and storage device, decompression can add time. Test the option with actual project data before deciding.

2. Add the proxy to the scene and preview it

To use the exported file, create a Redshift Proxy object in the Houdini scene. The documentation explains that you can do this using the Proxy option in the Redshift toolbar. Then specify the .rs file in the Proxy Filename field. If Enable Proxy File is turned off, the proxy won’t be displayed or rendered.

Choose a viewport display mode based on scene density. Bounding Box shows a simple bounding box around the objects instead of all the geometry in the file. Mesh displays the proxy geometry directly, while Points provides a point-cloud view. The None option hides the proxy in the viewport but does not prevent it from rendering.

Displaying a dense proxy as a mesh can reduce viewport performance. In that case, using Bounding Box or lowering Display Percentage can help limit the geometry load in the preview. For very dense proxies, the documentation recommends using a bounding box, a connected mesh, or a lower display percentage. For proxies containing curve data, Display Lines can turn off curve display in the viewport.

Consider the Animated Preview option for animated proxy sequences. When this option is off, the proxy remains static in the viewport but continues to update during rendering. Animated proxies can be heavy because of their per-frame caches, so choose whether you need a continuously updating preview while arranging the scene.

3. Plan attributes, materials, and animation in advance

When a proxy is exported, only the vertex attributes used by the shaders assigned at that point are included in the file. If you plan to change materials or apply overrides later, make sure to preserve the data the new shader will need—such as UVs and vertex colors—during export. For example, if the current shader doesn’t use UVs, UV data may be discarded; assigning a UV-based material later may then produce an unexpected result.

If you need motion blur, it must be enabled in the render settings at the time of export. Motion blur can be disabled after the proxy is created, but changing individual settings such as frame duration requires exporting again. For this reason, confirm your animation and motion blur requirements before creating the proxy.

The instancefile point attribute can call Redshift Proxies through instancing by using the file path. This can be output as Redshift Instances or Redshift Point Clouds. In scenes that require many copies, creating a single proxy and generating instances from it is more efficient in terms of memory and performance, according to MAXON documentation. However, material overrides are not supported with the instancefile attribute. Tessellation must also be fixed during instancing; adaptive tessellation cannot be used.

Considerations for architectural and archviz workflows

Architecture and visualization teams working with repeated plants, furniture, or similar scene assets can manage memory and performance by duplicating proxies within the scene. Using Bounding Box or a low Display Percentage while arranging the scene can especially help keep the viewport responsive. However, design changes require returning to the source geometry and generating the proxy again; a proxy does not replace the editable master file.

Redshift Proxy files can be used across different DCC applications, but shaders and light types specific to one application may cause problems in another. For sharing between applications, MAXON recommends using From Scene modes that use the materials in the scene. Compression can also be considered to reduce file size, but the decision should be based on network and storage speeds. Before rendering, check the applications in use, the material mode, and the required vertex attributes together.

Common mistakes

• Not keeping the source geometry: the original model mesh cannot be recovered from a Redshift Proxy file.

• Forgetting to export the UVs or other vertex attributes required by a material that will be assigned to the proxy later.

• Trying to use adaptive tessellation while instancing; fixed tessellation is required for this use case.

• Assuming motion blur settings can be changed after creating the proxy; some changes require exporting again.

• Enabling compression without considering network and storage speeds; the file may be smaller, but loading or exporting can take longer.